Luminous Landscape Forum

Equipment & Techniques => Digital Cameras & Shooting Techniques => Topic started by: Laco on January 24, 2004, 07:29:36 am

Title: The Missing Factor in Sony F828 Reviews
Post by: Laco on January 24, 2004, 07:29:36 am
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If we were to assume that the F828 Zeiss lens is sharpest at f5.6, then the fall-off at f8 is likely to be negligible, which would make the F828 an ideal camera for all those shots that require great depth of field.
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Who needs great (or greater) depth of field at focal lengths of 7 - 50 mm?
Title: The Missing Factor in Sony F828 Reviews
Post by: Howard Smith on January 26, 2004, 10:35:44 am
I think you need to read (review) Micheal's tutorial on understanding depth of field.  Using a 7 mm lens at f/8 then blowing up the result to same image size as your 200 mm lens will not change the depth of field.  They will be the same.
Title: The Missing Factor in Sony F828 Reviews
Post by: BJL on January 27, 2004, 10:24:16 am
Ray,

   you seem to working harder than necessary to prove an obvious advantage of larger formats: in exchange for the extra cost and weight of larger format equipment, including sensors with more pixels of the same pixel pitch compared to the smaller format alternatives, one is never worse off for image quality than with a smaller format; as a last resort one can crop down to a part of the image corresponding to what you would have got with a smaller sensor, using the lens's sweet spot in the process. Throw in a few reduced image circle wide angle lenses if you need to preserve wide angle coverage with such crops.

    Some more good news for big formats; in principal, diffraction limitation and DoF limitation scale the same way with image size and focal length: if you half the linear dimensions of the sensor (and of its pixels if you want to keep the same amount of detail in the image), half the focal length to get the same angular FoV, half the aperture ratio (i.e. keep the same aperture diameter), then you will half the diameter of the diffraction spot size and roughly half the CoC for any given out of focus part of the subject. Thus when you double the magnification to make prints of the same size, DoF and diffraction effects will be essentially the same.

   However, if one goes too far down in size, the larger aperture ratios needed become a problem; either completely impractical, or leading to increased optical abberations, so the image quality possible with very small formats will suffer. If one accepts the folk wisdom that f/8-11 is typically optimal for 35mm format, and Norm Koren's claim that f/4 is a lower limit in order to keep optical abberations well under control, the the lower limit for best quality seems to be about half of 35mm dimensions, or roughly 4/3" format.

   But maybe modern aspherical lens designs and such can push good performance down to f/2 which would bring 2/3" format back into the game; it is not fair to judge solely from the very wide ranging zoom lens of the Sony 828, so maybe the Leica lens of the Leica/Panasonic Digilux 2 is a better test.
Title: The Missing Factor in Sony F828 Reviews
Post by: Ray on January 28, 2004, 05:11:57 pm
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Why not keep ISO the same (same "film type) and let shutter speed take care of exposure?
Some good reasons; mainly because we can now use different ISO settings with the same ease as changing aperture or shutter speed, and shutter speed requirements are usually more critical for any given shot. If I'm hand holding the camera with a telephoto lens, I've got no choice but to use a higher shutter speed, or get a blurry image. If I'm shooting a Kung Fu demonstration out of the range of my flash, I've got no choice but to use a high shutter speed, or get unrecognizably blurry shots.

Unless it's a static subject and one is using a tripod, it generally makes more sense to choose the shutter speed and aperture and let the ISO fall where it will, rather than choose the ISO and aperture and let the shutter speed fall where it will.

That Photodo contest between 35mm and 9x12cm is fascinating. I've been aware of that for some time. It tends to imply if lens technology can progress to the point where it's actually possible to manufacture a lens that is diffraction limited at, say f2, and if it ever becomes possible to manufacture sensors that are capable of capturing that resolution of a diffraction limited F2 lens, then the larger format camera will no longer have an advantage, except perhaps for shallow DoF.
Title: The Missing Factor in Sony F828 Reviews
Post by: BJL on January 29, 2004, 11:03:03 am
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"Luminous Landscape" sot of implies the subjet and envionment we may be interested in.  Normally, cameras will be tripod mounted and shutter spedd will not be much of an issue.

If smaller is better, it strikes me as odd that folks much smarter than I (the Canon and Nikon pros for starters) are staying up nights trying to make bigger sensors.  What are they thinking?
Agreed on the first point: in the context of landscape photography, surely one of tests to do is ultimate image quality; and it seems almost certain that bigger sensors will continue to have the advantage there. Then again, I am sure that Michael never intended to use the Sony 828 as his primary landscape camera!

   About Canon, Nikon et al "staying up nights trying to make bigger sensors", the facts suggest otherwise.

   Agreed, in a small very high end sector, there is an understandable effort to produce "full frame" sensors which make the most advantage of existing high end 35mm and 645 format lenses, and it seems that with the recent 22MP MF backs, this ideal has been more or less reached in both formats. With no serious modernization going on in any of the larger versions of MF, I expect that 645 (56x42mm) will be the permanent upper limit on DSLR sensor size.

   On the other hand, these cameras and backs account for a tiny fraction of the total digital camera market. For the other 99.9%, there has been absolutely no trend to bigger sensors for some years, nor to bigger pixels. Instead, the dominant trend is gradually reducing photosite size and increasing pixel counts as technological change reduces noise levels and increases pixel read rates, while using the same or smaller sensor sizes.

    Since Howard mentioned Canon and Nikon in particular: Canon is not increasing sensor size in this "99.9% sector"; instead it seems to have settled on three DSLR formats of FF, 1.3x and 1.6x for three market sectors of "highest quality/MF replacement", "high quality with high speed", and "amateur", with no size increase ever in the last two sectors. Nikon has produced six DSLR models with no increase ever in sensor size from the 1.5x of its DX format, and is quite emphatic about staying at that size.
   Other DSLR players Pentax, Fuji, Sony (as sensor maker), Minolta and Olympus have also given no sign of increasing their DSLR sensor sizes, and in the one piece digicam market, there has been no sensor size increase since 2/3" format arrived more than three years ago.
Title: The Missing Factor in Sony F828 Reviews
Post by: Howard Smith on January 30, 2004, 08:55:53 am
Let's asume you are correct and one day there will be a 10gb sensor smaller than a bread box.  Even if such a sensor were perfect, the resulting images would be no better than the lens that formed it.  Just the same as an image formed by a perfect lens is no better tahn the film that records the image.  It does not make economical sense for one technology to progress much beyond the other.

There is room to grow in both optics and imaging, but don't too far ahead of yourself.
Title: The Missing Factor in Sony F828 Reviews
Post by: Ray on February 02, 2004, 03:04:44 am
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OK Ray, now I'm really confused.  On Jan 31, you said that the advantage of LF was not necesarily its superior lens, but the superior capabilty of the larger piece of film.  Then you seem to say that large format lenses are not superior to 35mm lenses.  Whih one is it?
Howard,
You're either playing games or being deliberately obtuse. (Never mind! I forgive you  :D )

Some 35mm lenses are superior to some LF lenses, and some LF lenses are superior to some 35mm lenses, in some ways. Not all 35mm lenses are equal and neither are all LF lenses equal. It depends on the design and construction of the lens.

With the digital system I've proposed, there is no noise  or grain to enlarge. Enlargement merely represents a dilution of the resolution that's on the sensor.

In practical terms, if one could manufacture a 4x5" slab of my super electronic material with 4 micron photodiodes capable of generating 256 discrete numerical values, it would definitely be overkill for the quality of current LF lenses, but the camera would nevertheless probably deliver better results at certain apertures, ie. more detail (but less DoF).

I'm assuming that the possibility of this happening is extremely unlikely considering how expensive the 1Ds sensor is. I think it would be fair and reasonable to predict that, in the unlikely event that this could ever happen, the extra cost would never remotely justify the marginal increase in resolution that might be achievable, and therefore no research dollars are likely to be forthcoming for such a project.
Title: The Missing Factor in Sony F828 Reviews
Post by: Ray on February 02, 2004, 08:22:09 pm
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The thread has strayed a bit from the original question, but the F828 is exceedingly sharp at F8.
Lin,
I'm glad to hear it! If we strayed a bit from the original issue it's because no-one has come up with the goods.

Thanks for posting that vibrant and spectacular shot of the painting. All we need now is a comparison between the F828 at f8 and the 10D at f13, of a highly detailed subject with the exposure the same in both cases.  :)
Title: The Missing Factor in Sony F828 Reviews
Post by: BJL on February 05, 2004, 01:50:16 pm
Ray,
    my example did neglect read noise, so armed with your correction and those "5 electron, 1 electron" claims for read noise, let me try again to seek some natural lower limits on pixel size. My answer will be "about 2 microns, maybe a bit less."

   Some dark current noise figures I have read are 17 electrons for the 6.8micron pixels of the E-1's sensor, 22 for its 16MP 9micron big brother in Michael's MF back, and about 8 for some digicam sensor, the Sony 5MP 2/3" one I think. These numbers seem to scale linearly in pixel spacing, or with the square root of photosite areas, exactly as theory suggests.

   So if read noise cannot be currently be got much below 5 electrons, we could be closing in on the idea that somewhere in the digicam pixel size world, around 3 microns maybe, read noise becomes significant in the deep shadows and sets a lower limit on desirable photosite size, while for anything on the present horizon in the DSLR world (6 microns and up?), read noise can more or less be neglected.

   However, the future is probably brighter: your 1 electron for CMOS figure meshes with reports I have read that there has been significant recent progress in noise reduction in the CCD designs for digicams, and that this is closely related to the trend towards smaller digicam photosites. So maybe we should be cautiously optimistic, and look to 1 electron read noise in the not so distant future. (Do you really believe that CCD's are old hat and that most or all present progress is in the CMOS world? If so, explain it to all the digital back makers, and to Fuji, whose SuperCCD is the high resolution, low noise measurement leader in the APS DSLR field.)

   With dark current noise apparently scaling in proportion to photosite spacing, it can be expected to be more than 1 electron down to pixel spacing of about 6.8/17 =.4microns; smaller than the wavelength of light! So read noise would be practically irrelevant: even at 2microns it would be only one fifth of expected dark noise.

   As an aside, several sources (including Nikon) suggest that below about 2 microns, lens resolution limits mean that you will get little or no resolution gain with further sensor resolution improvements.

  If the limit is 2 microns, I can only dream of 60MP in a 4/3, or 90MP in a Nikon DX, leaving 100MP plus to Canons's 1.3x and full 35mm format territory.


P. S. Can you give me a source for that "Read Noise figures as low as 5 to 11 electrons for CCDs with a full well capacity of 45,000 to 375,000 electrons."?  Because if it means "5 for 45,000 and 11 for 375,000", then there is a considerable reduction of read noise with pixel size, very close to my beloved square root pattern. Remember the idea that, due to the noise reduction effect of downsampling and printing at higher pixel density,

"So long as reducing photosite spacing with constant sensor size causes a noise source to reduce at least in proportion to the square root of signal (i.e. linearly in pixel spacing) there is no loss in image quality."
Title: The Missing Factor in Sony F828 Reviews
Post by: Ray on February 08, 2004, 08:44:08 am
BJL,
Quite amazing really! Now all we need is someone like yourself to translate all this stuff into laypersons' terms  :D .

I'm still none the wiser as regards the image quality limits of the small sensor. It might seem that, as sensor size decreases photon noise increases in significance, as do all other types of noise. The square root of 10 million is a bigger percentage of the total than the square root of 10 billion, and so on.

I've come across statements that nothing can be done about photon shot noise. We're up against fundamental laws of Physics. But that doesn't seem quite true to me. You can always reduce photon noise by letting in more light, ie. reducing ISO, and at the same time effectively reduce all (?) the other types of noise.

Do you know of any fundamental limits? Perhaps photodetectors that are smaller than the wavelength of the light they are intercepting? But I'm not even sure about that. Doesn't light have a weird habit of turning into a particle when we try to catch it?  :D
Title: The Missing Factor in Sony F828 Reviews
Post by: Howard Smith on February 09, 2004, 04:26:26 pm
I am not trying to be difficult, but you say some interesting things, like small sensor size will be optimal for "a great majority of photographers" and that larger sensor will never drop below a price suitable for "professionals and very serious amateurs."  I think those very same statements can be made for film.

I am jumping to the conclusion that a small number of photographers (call them pros and very serious amateurs for lack of a better term) may be willing to spend more for a digital camera with a larger sensor.  But why?  If there is no advantage, even a small one, why pay more?  Most pros aren't that stupid, or they would be starving.  But if a larger sensor is at least SOME better, then it is better, regardless of cost.  Small becomes only a better value for the dollar, not a better camera.  Just like medium format is generally more expensive than 35mm, but for some, it is worth the expense, and the bulkier cameras are not a problem.  Same for larger formats.  It's not for everyone, but the images large format can take are better than 35mm.

I will readily acknowlegde that it is not all wrapped up in image quality.  I use medium and large format film.  One reason is I like just like to, even if a 35mm Canon was just as good or better.  I like to fiddle with the manual controls of a 4x5.  I like the kerplunk my Hasselblad makes when I trip the shutter.  It's not a tiny beep.
Title: The Missing Factor in Sony F828 Reviews
Post by: BJL on February 10, 2004, 02:29:30 pm
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In 3 µm sensors, even if you leave the read-out-error and thermal noise aside and thus go down to abt. 100 electrons or 300 photons (giving a 10/1 S/N-ratio), you'll have roughly 500 distinguishable steps of intensitiy (by dividing the [18,000;300]
The noise level is (at minimum) square root of electron count, so at 100 electrons, the photon noise level is 10 and the next distinguishable level is about 110. Moving up, the noise level grows with the signal, so the distinguishable gaps spread.
   Optimistically considering photon noise only, about ten levels couldbe distinguished in the lowest f-stop, 14 in the next, 20 in the next, and so on up to 56 in the topmost of the six f-stop range; at most about 160 levels. Almost but not quite enough to use all the 256 levels available in 8-bit output; the 2.7 micron photosite really looks as if it is close to the edge, until the highlight capacity of such small wells can be improved.
Title: The Missing Factor in Sony F828 Reviews
Post by: Digi-T on February 18, 2004, 04:43:23 pm
You're right, we're not listening anymore so please keep going  :laugh:  Woo hoo, page 11.

T
Title: The Missing Factor in Sony F828 Reviews
Post by: Howard Smith on February 19, 2004, 07:20:31 pm
Ray, the brown moth thing is bunk.  It was later discovered that the spotted moth does not rest on tree truncks or branchs.  The moths used to support that rot were dead and glued or pinned to trees to prove the theory.

Thank who?

Sorry I ot you and BJL confused.  I'm also confused about why you care about the "Christian movement."  I am laboring under the opinion you are an atheist.
Title: The Missing Factor in Sony F828 Reviews
Post by: Howard Smith on February 20, 2004, 09:20:41 am
Ray, like I said, the gurus of evolution aen't about to let there followers know their theory is in real trouble.  So they don't advertize their failures.  I don't think there was any intention of fraud when the peppered moth story came out.  The only raud is contiuing to peddle it as true when the flaws are known.

I am sure that believers in God are not foolish like atheists.  For a second, let's assume I am wrong - there is no God.  What harm have I done myself or anyone else by living the life of a believer?  But the long term harm for the atheist and the agnostic is unspeakable if they a wrong.  When you meet God, are you going to be provocative and deny Him?  Might as well.  It will too late to embrace Him.

John, if you find a "church" that is "all right," give me a call.  I want to join.  Don't let misguided theologians run or ruin your life.   Jesus did not teach theology, but the nature of God, man, life and the world and the relationships betwen them.  If you study the Bible, you will find the people he had real problems with were the church.  I think Jesus is vy unhappy with churches today.
Title: The Missing Factor in Sony F828 Reviews
Post by: Ray on January 22, 2004, 08:04:02 pm
There's an interesting example on dpreview of the F828 purple fringing issue at various apertures. It's called the foil 'torture' test.

At f2, PF is just horrible; at f4 somewhat reduced; at f8 it's virtually all gone.

It seems that, for those who are particularly concerned about this issue of CA, there is a solution. Just use f8.

Okay! It's understood you don't want to use f8 all the time, but the fact that you have that option to slay the dreaded Purple Fringing ogre in one fell swoop is surely significant.

The only good reason I can think of why this solution might not appeal, is the possibility that resolution at f8 is compromised as a result of the very small 2/3rds sensor requiring a greater degree of enlargement for any size print.

In other words, the very fine Zeiss 28-200mm zoom does not have optimum performance at f8. Maybe! Could someone please do me a favour and find out if this is true, because the foil 'torture' test images at dpreview 'appears' to show better resolution at f8.

As most of us know, 35mm lenses tend to have their best performance at f8. Occasionally, a lens will have its best performance at a bigger aperture, especially really expensive telephoto primes, but when this happens that extra performance at, say f4 is very marginal (compared with f8).

I would expect the performance of the Zeiss zoom to be best at around f2.8. But it would have to be significantly better than at f8 to make f8 an unusable solution to PF, especially considering the tremendous DoF advantage at f8, equivalent to almost f32 on a 35mm camera.
Title: The Missing Factor in Sony F828 Reviews
Post by: Scott_H on January 24, 2004, 09:40:13 am
I could see it being useful, just as I could see the lack of background blur at large apertures being frustrating.  It depends what you are trying to do.
Title: The Missing Factor in Sony F828 Reviews
Post by: Ray on January 25, 2004, 11:46:15 pm
Okay! Let's try to make this crystal clear. Manufacturers of digicams, more often than not, give us a 35mm equivalent for focal length because that's what so many of us are used to, but they neglect to give us a DoF equivalent.

I don't know why this is. I can only assume it's because DoF is considered to be more esoteric than focal length and most buyers of P&S digicams wouldn't have a clue what DoF means.

On the other hand, to be fair  :D , it might be because the aspect ratio of the 2/3rds format is different from 35mm, so the 35mm DoF equivalent is not one easily defined figure. It depends on where you've positioned yourself at the time the photo is taken. Are you cropping the 4:3 format of the F828 to equal the 3:2 format of 35mm, or not? Do you want that extra horizontal expanse or not? If you don't, you can get closer to the subject, or use a slightly greater focal length setting on your zoom, and that affects the DoF.

Either way, the DoF equivalent at any given aperture is significantly greater for the smaller format. For equal horizontal FoV it's about 4 F stops, and for equal vertical FoV it's about 3 1/2 F stops, in the case of the 2/3rds format versus 35mm.

I'll use the greater figure for ease of calculation. I'm using a 200mm lens on my 35mm camera and I'm shooting a scene with some interesting stuff in the foreground which I want to be sharp. My lens is likely to be sharpest at f8, very nearly as sharp at f11, a bit off at f16 and decidedly fuzzy at f22.

I have a problem deciding whether or not to use f11 or f16. I know I'm going to blow up this photo to A3+ so I decide to use f11 and the hyperfocal distance principle (bring focussing back slightly from infinity), but I also know that F11 is not going to give me sufficient DoF to get everything sharp that I want to be sharp. I'm between a rock and a hard place.

But hey! Maybe there's a solution. I pull out the F828 from my bag. This lens is sharpest at F5.6, equivalent to f22 on my 35mm camera. Wow!

Maybe the F828 lens is also equally sharp at f8. That's equivalent to f32 on my 35mm camera. Extra wow!

On the other hand, maybe the performance of this Zeiss lens really sucks at f8. I just don't know. The dpreview foil test gives the impression that resolution is actuall better at f8, but I find this difficult to believe.

So, I'm hoping some of you brave owners of the F828 will risk personal trauma and do a few experiments at various apertures and let me know what the results are. I know it's a lot to ask. If you discover that performance at f8 is really lousy, this could make you angry and depressed for days. It's a great risk, but in the greater interest of scientific objectivity, which we can all benefit from, I hope at least some of you will oblige.  :)
Title: The Missing Factor in Sony F828 Reviews
Post by: BJL on January 27, 2004, 10:39:22 am
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Yes, depth of field calculators do use different size circles of confusion for different formats. You should read the fine print to understand why. The reason is smaller formats are usually enlarged more than larger formats.
Good, it seems that we are all now in complete agreement on the practical point, which is that one DOES have to take format size into account in order to make a useful DoF calculation, because DoF calculations for different formats are and should be done with CoC values adjusted roughly in proportion to the format used.

   (I clearly have read the fine print, since that point about using different magnifications for different formats is one that I have been making repeatedly from the beginning, and that Ray has also discussed.  I do not understand why you think you need to explain it to us at this stage!)
Title: The Missing Factor in Sony F828 Reviews
Post by: Howard Smith on January 28, 2004, 03:36:19 pm
There is an article on photodo that attempts to demostrate that 35mm can be as sharp as medium and large format.  In that demonstration, each format is tested with a "normal" focal length lens for each format (50mm, 80mm, and 150mm).  This gave each example the same "perspective."

The lenses were stopped down to an f/stop to produce the same depth of field for each focal length.

The same film (same ISO, not varied) is used for each format (T-Max 100).  Shutter speeds are set for the correct exposure (varied, not constant).

In the comparison proposed above, it is suggested the ISO be adjusted so that shutter speeds would be constant.  That seems to favor the Sony since the higher ISO for the D10 would be presumably noisier.  Why not keep ISO the same (same "film type) and let shutter speed take care of exposure?

The result was the 35mm as sharp but grainy compared with its bigger brothers.
Title: The Missing Factor in Sony F828 Reviews
Post by: Ray on January 29, 2004, 05:40:03 am
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I wonder why NOBODY criticizes the biggest flaw in 828 - the quality of the electronic viewfinder.
There have been lots of discussions on this forum regarding the benefits and disadvantages of electronic viewfinders. I get the impression peoples' opinions will vary depending on what they are used to. It's not a big issue for me. However, I don't think it's entirely natural to squint at the world with one eye.  :D
Title: The Missing Factor in Sony F828 Reviews
Post by: BJL on January 30, 2004, 02:35:52 pm
First, an aside: Ray envisions a purely "discrete" sensor with one bit output at billions of photo-sites; that is actually a description of silver halide film! All smooth tonal variation in a traditional black and white negative or print is an illusion produced by blurring of the image from a vast array of tiny, pure black or pure white pixels. (Conclusion; photsites with extremly low S/N ratio and low bit level output can produce wonderful results so long as each individual pixel prints very very small!)

    Second, indeed, "digitial cameras" actually use an analogue electronic sensor, some analogue amplification and maybe analogue noise reduction processing before converting to digital, and many image quality issues depend on performance in this analogue stage, so long as one avoids cutting down to 8-bits. (A/D converters tend to have higher accuracy that the signal going into them.) The sensor does enforce "spatial discretization" though.
The French sometime talk of "electronic cameras", and that is arguably more accurate.
Title: The Missing Factor in Sony F828 Reviews
Post by: Howard Smith on February 01, 2004, 11:01:11 pm
OK Ray, now I'm really confused.  On Jan 31, you said that the advantage of LF was not necesarily its superior lens, but the superior capabilty of the larger piece of film.  Then you seem to say that large format lenses are not superior to 35mm lenses.  Whih one is it?

I still maintain that if you put a 4x5pice of that super electronic Fujichrome in a 4x5, it will shoot the socks off any 35mm, just the same as with T-Max 100 or whatever film.  The difference will still be the larger image on the 4x5 does not require the same enlargement.
Title: The Missing Factor in Sony F828 Reviews
Post by: Ray on February 02, 2004, 09:39:38 pm
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first, I have asked indirectly before but am still curious: how do you come to your conclusions about the resolution and noise performance of the E-1?

Only from lab test results. I accept that a slight increase in noise at 18% grey on a chart, or very slightly less resolution compared to the 10D at 100% on a screen can amount to nothing on a print. I'm trying to be objective using terms that are relative. The E-1 sensor seems to be the weak link in the chain. People often comment that the Zuiko lenses are as good as Canon L glass. In fact, the MTF charts (if we can believe them, because I know of no independent MTF tests) would indicate the Zuiko lenses are considerably better than any Canon lens that I've seen, in relation to its MTF performance at least. Some of these Zuiko lenses appear to have the same performance at 60 lp/mm as the best Canon lenses have at 40 lp/mm.

Apologies to any E-1 owners who get the impression I might be trying to disparage the performance of their new pride and joy.  :D

On the issue of larger numbers of smaller pixels being able to do as well as smaller numbers of larger pixels, I think we're really fudging the results a bit, don't you? It's a game in which dynamic range is always going to be limted and the additional noise is always going to be there, sometimes very apparent, sometimes hardly apparent and sometimes not apparent at all, depending on print size and what clever strategies have been put in place, or employed in post-processing, to reduce the noise.

A fully digital sensor is the way to go, whether along the lines I've proposed or not. At the risk of stating the obvious and teaching people how to suck eggs, it must be apparent that the enlargement issue disappears with a 'true' digital sensor. The number 'four' means what it means, whether it's writ large or small.
Title: The Missing Factor in Sony F828 Reviews
Post by: Ray on February 05, 2004, 10:01:26 am
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which conditions were convoluted?
I was hoping you wouldn't ask me. That was my euphemistic way of saying 'confusing and contradictory'.  :)

After explaining why larger numbers of smaller pixels should or could have the same performance (when summed) as an equivalent number of larger pixels, you then proceeded to give an example of binning which appears to demonstrate the opposite.

Binning only serves a purpose because it reduces the total noise of the pixels that have been binned. There's an implication in Roper Scientific's explanation of this term that Read Noise might be the same for both large or small pixels.

Unfortunately, Roper Scientific seems to deal with CCDs rather than CMOS devices, so their figures might be out of date. They give examples of Read Noise figures as low as 5 to 11 electrons for CCDs with a full well capacity of 45,000 to 375,000 electrons. That's certainly insignificant for large pixels at full saturation but could be a problem for small pixels in low light situations.

I'm tempted to speculate that the F828's high noise at ISO settings of 200 and above is due to the prominence of Read Noise relative to the signal. On the other hand, I read somewhere that CMOS sensors can now have a Read Noise as low as 1 electron.  ???

Thanks for pointing out that mistake of F13. That is of course equivalent to the F828 at F5.6. F20 it is then (or nearest setting).  :D
Title: The Missing Factor in Sony F828 Reviews
Post by: BJL on February 09, 2004, 11:44:18 am
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I've come across statements that nothing can be done about photon shot noise. We're up against fundamental laws of Physics. But that doesn't seem quite true to me. You can always reduce photon noise by letting in more light, ie. reducing ISO, and at the same time effectively reduce all (?) the other types of noise.

Do you know of any fundamental limits?
Fundamental limits are the easy ones! All one needs to know is the appropriate physics, not the engineering trade secrets of the camera companies.

    The most famous fundamental limit is what I call quantum mechanical counting error noise, both photon noise and other sources based on counting photons and electrons. This limits S/N ratio to the square root of the number of items counted. It is the one that says, if photosites have a maximum electron count proportional to area, decreasing photosite size will decrease photosite S/N ratio in proportion to the linear dimension of the photosite, so shrinking sensors reduces possible dynamic range for a given amount of spatial detail [i.e. a given pixel count].

   The only way to mitigate this problem is your idea of allowing the sensor to handle more light (quantum mechanics says that more light = more information = greater total combination of spatial detail and tonal gradations). For example, deeper electron wells, or Fuji's twin photodetector idea, or an idea that has been floated of measuring how long it takes for highlight pixels to blow out and hence determine highlight luminosity levels at blown-out pixels by extrapolation, or my new idea of repeatedly reading out and emptying photosites at high rates to avoid any overflows.

   A possible second almost fundamental limitation is optical limits on minimum aperture ratio, related to optical distortion and maximum deviation from perpendicular of the angle of incidence of light on the sensor. Digital cameras will probably never be able to make much use of aperture ratios faster than f/1, and f/1.4 is a more plausable value: with lower aperture ratios, the extra light coming from the outer edges of the wider aperture will scarcely be detected.  This is the one that is likely to cause maximum usable system speeds (lens plus sensor) to decrease in proportion to sensor/photosite area.

P. S. The trend of high end digicams with lots and lots of tiny, roughly 2.7micron pixels has now spread to almost every major player: Canon, Konica-Minolta, Nikon and Sony with 8MP 2/3" format, Fuji with 6MP 1/1.7". Is it possible that none of them understands the inherent undesirability of such small photosites, or that Canon, Nikon and Konica-Minolta have decided to produce raer expensive products that are both inherently flawed and enrich major competitor Sony by using their 8MP sensor. Canon has stuck their neck out on the 8MP PowerShot Pro1 by calling it a "pro" product and giving the "L" designation to the lens.
Title: The Missing Factor in Sony F828 Reviews
Post by: BJL on February 09, 2004, 06:11:27 pm
As I said a while  ago, in principle a larger format can do everything that a smaller format can, if you are willing to bear the price and weight: the basic stategy is for the larger sensor to have the same pixel size as a smaller one, allowing one to effectively crop down to the smaller sensor when that gives the best results. Maybe some shot focal length lenses of smaller image circle and faster maximum lenses (like the new wave of "digital LF lenses") would also be useful when doing such cropping.

    However, this seems about as relevant as when some large format zealots ridicule 35mm and even medium format, or when LF users and writers like Roger Hicks in Popular Photography manage to ignore the more restrictive shutter speed needs of making larger format images. It is certainly not relevant to the original, long lost topic of this thread; deciding whether the Sony 8MP 2/3" sensor is a "Good Thing" for some photographers at least.
Title: The Missing Factor in Sony F828 Reviews
Post by: Howard Smith on February 10, 2004, 12:20:55 pm
Ray, I can live with the 828 being a 2/3" camera with a 7-50mm f/2 lens because I am pretty sure that is what it is.  BJL, I will freely admit that the 828 is a "good thing" for at least some people.  In fact, it is too much of a good thing for my Aunt Tilly, and not so much of a good thing for others.  Michael carries one around and uses it sometimes, but not all the time.

You certainly didn't need to get into photon counting to convience me of that.  And why level the field?  If I can take "better" images with my Super Zoomoflex, why do I have to crank up the ISO and stop the lens way down to show it doesn't take "better" images than an 828?
Title: The Missing Factor in Sony F828 Reviews
Post by: BJL on February 18, 2004, 04:35:40 pm
Quote
BJL, why can't a debate of God be rational? ...
I am sure it can be: I was an enthusiastic student of the philosophy of religion in my younger days, and still follow various religous debates, and not just ones about the infalibility or evil of various camera makers. On the other hand, it seems that on the internet as a whole, it is hard enough to keep even a debate of photography rational!

(I suppose that on page ten of a thread, we can discuss almost anything, since almost nobody is listening any more!)
Title: The Missing Factor in Sony F828 Reviews
Post by: Ray on February 19, 2004, 07:02:55 pm
Quote
Ray, I certainly don't know you are right.

For natural selection to work, the mutation must be beneficial or attractive for the organism - give it an edge.  
Well, I thought I'd already explained that  :D . Mutation is not the driving force or primary mechanism of Evolution. I'll give you an example. A species of moth in pre-industrial England is a pale brown colour that blends in nicely against tree trunks etc. This protects the moths from being gobbled up too frequently by predatory birds. There's a balance created.

Along comes the industrial revolution and covers everything in a layer of soot (no exaggeration! We've got it good with our clean air policies). The once brown tree trunk is now grey. This species of moth almost gets wiped out. It can't hide itself and is picked off too easily by the birds.

Thank God for variation within the species! Just a few moths are a slightly darker shade of brown. They are the ones who tend to survive and their offspring are also a slightly darker shade of brown. And amongst those offspring there is variation and some are an even darker shade of brown. Within 50 years or so, that species of moth has completely changed colour and is thriving as strongly as ever.
Title: The Missing Factor in Sony F828 Reviews
Post by: BJL on February 20, 2004, 09:31:10 am
Quote
Keep in mind that ONE misplaced acid is usually fatal.  Sickle cell anemia is an example.
I will not even begin to try to change anyone's religious views based on reading or religious writers, but simple errors of fact I will address. it is far from true that "One misplaced acid is usually fatal"; on the contrary, there are considerable variations in DNA that cause no phenotypic effect, and considerable genetic variations in the the details of proteins that have little or no effect on their functioning.
   Also, sickle cell anemia is a very poor example; it is related to a genetic variation that is overall beneficial in Africa, where it is most common, by imparting a degree of resistance to malaria to those who inherit that version of the gene from only one parent; only the smaller number of people who inheret it from both parents suffer sickle cell disease. And I believe it is far more than a one acid change away from regular haemoglobin.
Title: The Missing Factor in Sony F828 Reviews
Post by: Scott_H on January 22, 2004, 09:52:52 pm
Typically CA is only going to show up in extremely high contrast situations.  In those situations the image probably isn't going to be acceptable anyway; since you are probably exceeding dynamic range, and chances are your highlights are blown.
Title: The Missing Factor in Sony F828 Reviews
Post by: BJL on January 23, 2004, 05:06:31 pm
Quote
Lenses have normally their best performance at 2-3 f-stops from being wide open. After that their performance slightly decreases.
I wonder if that guideline carries over the the world of far smaller image circles and focal lengths?
   One suggestion at Norm Koren's site is that lens abberations starts to be the dominant factor in image quality at f/4 and wider, and he implies that this is an inherent limitation in optical design (dealing with coma, spherical abberation and all those other things that I know little about except their names).
   So maybe we should be looking for small 2/3" format digicam lenses to be at their best roughly between f/4 (to limit aberrations) and f/8 (to limit diffraction).
Title: The Missing Factor in Sony F828 Reviews
Post by: BJL on January 25, 2004, 09:07:41 am
Quote
Who needs great (or greater) depth of field at focal lengths of 7 - 50 mm?
In the 2/3" format of the Sony 828, those focal lengths cover the same angular field view range as about 28mm to 200mm in 35mm format (as I am sure you know, but for some reason overlooked), which covers the FOV choice in a great majority of all photgraphs. So the answer would seem to be "almost anyone who wants lots of DOF in a photo". Like me with almost every photograph I take of landscapes, urban scenes, and close ups. (It seems to be that the DOF characteristics of small digital sensor formats are particular attractive for close-up/macro photography.)
Title: The Missing Factor in Sony F828 Reviews
Post by: Howard Smith on January 26, 2004, 01:00:14 pm
Perhaps this would make more sense and be easier to understand if everyone used the same definitions and the one most commonly accepted.  Depth of field is simply the distance in front of plus behind the plane of focus that prodcues a circle of confusion defined by the user as "acceptable" for sharpness.  Frm that, you can decide for yourselfwhat is sharp and what isn't.  Somewhere someone said something about at what f/stop does a Canon50 mm f/1.4 lens bwcome "razor sharp."  Well, that is a very qualitative staement.  Maybe for some it is "razor sharp" at every f/stop and for some it fails miserably at every f/stop.  It is dangerous to make critical comparisons using ill-defined terms to describe qualitative traits.
Title: The Missing Factor in Sony F828 Reviews
Post by: Ray on January 26, 2004, 10:29:55 pm
And I thought I could be crystal clear on this matter. I don't know what came over me!  :D

I'm afraid BJL is right, Howard. It's not just the size of the circle of confusion that counts, but its size in relation to the whole image.  A CoC of diameter 0.01 inches might be insignificant on an 8x10" film, but very significant on a 2/3rds format sensor.

However, you are quite right that in order to calculate the diameter of the CoC (on the film or sensor) at a particular distance from the camera, say with the lens focused at infinity, the format or size of the film or sensor is irrelevant and doesn't come into the equation.

As I understand it, the fundamental formula for such calculations, with lens focussed at infinity, is CoC = focal length squared, divided by (f stop x distance of subject from camera). Focal length and distance should be in the same units of course.

What I'm trying to find out is; can the small format camera do anything that the larger format cannot? We know that the small format digicam is at a disadvantage as regards shallow DoF. Is this counterbalanced by a greater DoF capability whilst still maintaining good resolution?

According to Fabio, the F828 Zeiss lens is sharpest at F5.6. This seems to accord with the aperture Michael chose in his test review of the F828, comparing it with the 10D.

Now, according to my calculations, the F828 at F5.6 gives the same DoF as the 10D, at equivalent focal lengths, using an aperture of f13.5 (2 1/2 stops difference). I don't think any of my 35mm lenses would have their best performance at f13.5. At that aperture, it probably wouldn't make any difference what type of lens one used, a $5,000 Canon prime or a $500 Sigma zoom.

I'd be really interested to see how these two cameras perform at these relative apertures. Will the F828 really shine, or will resolution still be roughly on a par with the 10D?

What about comparing the F828 at f8 with the 10D at f19?

In the meantime, I'm going to work on that basic formula and see what the CoC's should be. However, my experience tells me there's often a discrepancy between theory and practice.
Title: The Missing Factor in Sony F828 Reviews
Post by: Howard Smith on January 26, 2004, 10:30:53 pm
Here's an exercise for you, BJL.  I will cut a 1x1 inch piece of film from a negative I have taken.  I will tell you the lens focal length, the f/stop used and the focus distance.  Please calculate the format for me before I cut the film.  If you can tell a 1x1 inch piece from the middle of a 4x5 taken with a 150 mm lens @ f/8 from a 1x1 inch piece taken cut frm a 6x6 cm taken with a 150 mm lens @ f/8, I will be completely amazed.  You can't.  Format has no input.  Yes, I suppose you might get a hint from the thickness of the film base, but that doesn't count.

Here's the truth.  I you want to compare a print from a small digital sensor to a print from  a large format negative, you will likely choose a much smaller circle of cofusion for the digital image because you will likely need to enlarge it more.  BUT, if the image size (the size of the bord on the wire) i the same for both prints, then only the f/stop matters, given the same focus distance.  The format and focallength have no input.

Last excercise.  Read Michael's tutorial on Understanding Depth of Field.
Title: The Missing Factor in Sony F828 Reviews
Post by: BJL on January 27, 2004, 09:43:42 am
Quote
Here's an exercise for you, BJL.  I will cut a 1x1 inch piece of film from a negative I have taken. ...
Howard, some comments and questions.

Comments:
1) You are the one who needs to reread Michael's essay of DoF. He points out that the CoC choice is computed backward from a roughly one minute of arc resolution limit fort the eye, and a resulting 1/6mm resolution limit on prints viewed from about 15" [50cm], and thus CoC choice depends on the expected maximum magnification (about 5x traditionally for 35mm format). He goes on to mention that for larger formats like 8"x10", CoC is typically computed using a larger CoC value due to the lower magnifications factors likely to be used in printing. It is exactly the same reasoning which says that for digital cameras with very small sensors, small pixels and hence large magnification factors often used in printing that smaller CoC values should be used.

2) You comparison of equal areas of film is mostly relevant if one prints with the same magnification regardless of format and view the prints from the same distance despite their different sizes. In our digital example, it would apply to making a 12"x9" print from a 2/3" camera and a 50" by 33" print from 35mm format, and viewing them both from the same distance. Even if one were to make such a huge print from 35mm format, it would typically be viewed from far further back, which increases the perceived depth of field because of that roughly one minute of arc resolution limit mentioned in Michael's essay.


Questions

Have you noticed that the DOF calculator I mentioned adjusts the circle of confusion roughly in proportion to format size, (as does every DOF calculator covering digital formats that I have seen)? If so, do you claim that they are all wrong, and that instead they should be using the same CoC value regardless of format?
Title: The Missing Factor in Sony F828 Reviews
Post by: Ray on January 27, 2004, 07:32:38 pm
Quote
  you seem to working harder than necessary to prove an obvious advantage of larger formats.
BJL,
That's odd!  :)  I thought I was doing the opposite. I'm trying hard to find a 'real' advantage of the smaller format, apart from the obvious fact that smaller format cameras are, or can be, lighter and less bulky.

I'm still a bit uneasy about the way Michael has compared the F828 to the 10D. I get a sense of apples and oranges. There doesn't appear to be a level playing field. On the other hand, it might be (more likely  :) ) I just don't understand the significance of his methodology.

When taking any photo, major considerations are; what angle of view? what depth of field? what shutter speed?

With modern digital cameras with adjustable ISO, selection of shutter speed is also going to be influenced by increased noise considerations. (Perhaps more than is necessary in my case, but that's another matter.)

When comparing two quite different cameras such as the F828 and 10D, in order to keep the playing field level and compare apples with apples, it seems to me that one should keep equivalent focal lengths (same angle of view), keep equivalent DoF (different f stops), and keep the shutter speed the same (different ISO settings).

Michael doesn't appear to have done any of this (at the camera level) in his comparisons. He seems to have used the same aperture for both images (f5.6) which ensures that the 10D image will have less DoF. He seems to have used a Canon lens at 200mm, which is the full frame 35mm equivalent focal length, not the 10D focal length equivalent, and by comparing the F828 at ISO 64 and/or ISO 100 with the 10D set at ISO 100, he's given the F828 simultaneously a shutter speed advantage and a noise disadvantage, which sort of confuses the issue.

If I were setting up these two cameras for comparison, I'd be comparing the F828 at 200mm and F5.6 (actually 50mm and f5.6) with the zoom on the 10D set at 120mm and f13. Or, I'd use f4 on the F828 and f9.5 on the 10D. This would ensure equal DoF for both images.

I would also set the F828 at ISO 100 and the 10D at ISO 400 to ensure equal shutter speeds, as well as ISO 64 and ISO 250 (if that were possible). Clearly, exact equivalence is not always possible.

Now, before anyone jumps on me for criticising Michael's methodology, let me say that his methodology appears to understate the performance of the F828, and this might be quite deliberate in order to deflect criticism.  :)
Title: The Missing Factor in Sony F828 Reviews
Post by: Ray on January 28, 2004, 06:46:20 pm
Quote
P. S. want to redo this whole debate with the next 8MP 2/3" format digicam, the Nikon 8700 with is 8.9-72mm [35-280 equiv.], f/2.8-4.2 lens?
No need, if Michael includes my testing recommendation of level playing field  :D .

We need to know the maximum image quality attainable, despite different settings and different equivalent settings, for each camera, as well as image quality at equivalent DoF and same shutter speed.

What seems to be happening at present is a state of confusion where someone who owns a small digicam might be under the impression that he/she can take a photo in a nightclub with no flash, at f2 and get reasonable DoF and results that cannot be achieved with, say the larger 35mm camera which would produce an undesirable shallow DoF at F2, and that therefore the small digicam has some advantage in this respect.

This is, I believe, illusory. One simply stops down with the larger format to get equal DoF and goes up in ISO to maintain the same shutter speed, and the quality of the images should then be roughly the same, at least in terms of noise.
Title: The Missing Factor in Sony F828 Reviews
Post by: Andrzej Poniatowski on January 29, 2004, 12:46:08 am
I wonder why NOBODY criticizes the biggest flaw in 828 - the quality of the electronic viewfinder. I think that the camera deliveres very good quality images (fantastic value for money) BUT looking throught the viewfinder makes me "sick" and "unwilling" to photograph - though I know that ALL will look much better later.....
The viewfinder made me send the camera back! No more electronic viewfinders! Bought E-1 instead!
Title: The Missing Factor in Sony F828 Reviews
Post by: Howard Smith on January 30, 2004, 12:07:47 am
Gosh Ray, was that a compliment?  Unless quantum mechanics has changed a great deal since I was in college, I think I can understand and appreciate the subtle difference betwee digital and analog.  But feel free to explain it if you must.
Title: The Missing Factor in Sony F828 Reviews
Post by: BJL on January 30, 2004, 02:54:02 pm
Quote
BJL, I would point out that except for Pentax and Fuji, I don't think any camera maker you mentioned is a player in the medium format market.
Howard,

   even ignoring medium format, there is room for Nikon, Fuji, Pentax and Sony to try to move DSLR sensor sizes up towards 35mm frame size, but, contrary to your claim that "(the Canon and Nikon pros for starters) are staying up nights trying to make bigger sensors" I know of no evidence that Nikon or any of these companies are trying to do so. There is also room for all digital camera makers to move towards bigger sensors for digicams than the current 2/3" limit, but there is no sign of movement there either.

    Could you give some evidence for your claim that Canon and Nikon engineers are working on increasing sensor sizes, or of any current effort to increase sensor sizes other than in the medium format back realm?
Title: The Missing Factor in Sony F828 Reviews
Post by: Howard Smith on January 31, 2004, 06:20:24 pm
Perhaps the key word is "amateur  I think with that there comes things like cost and the need ot desire to make really big prints.  When amateur cameras start racking a thousand US dollars or two, the market must drop off pretty fast.  Too expensive for the amateur and not good enough for the pro and very serious amateur.

I have very little knowledge about electronic cameras, but with film there is an advantage to size.  Larger fil can make larger prints with less grain and lower quality lenses.    I have two 4x5 lenses that cost less than one Hasselblas lens, and they work just fine.  Perhaps if film (or electronic Fujichrome) were to get so good that a fine 30x40" print equal to a large format camera could be made from a less than 35mm digital camera, then large format would get pushed to better lenses and bigger electronic Fujichrome.  Of course, here will be some limit beyond which no one cares if a print that big could be made of no one but the government could afford it.
Title: The Missing Factor in Sony F828 Reviews
Post by: Ray on February 01, 2004, 06:34:17 pm
Howard,
I knew you knew that!   I've also known it for some time. The obstacle is in the concept of a 'perfect' film (or sensor). With analogue processes, improvements happen gradually and by small increments. If cameras had not gone 'digital', sort of, (they're not yet truly digital) film might never have progressed to the point where it could be so fine grained and have a sufficiently high MTF response, at say 60 lp/mm, that 35mm could rival the quality of 9x12cm or 8x10 in normal, everyday conditions.

A similar analogue problem now plagues so-called digital sensors, which gives the edge to the larger sensor. The smaller the sensor and photodiodes, the greater the noise and the smaller the dynamic range. The closer one gets to capturing the full resolution of the smaller format lens, the more apparent the noise becomes at equivalent enlargement and the more difficult it becomes to maintain a DR that at best is rarely equal to that of negative film in the current crop of digital cameras, at any price.

By designing sensors that are truly digital, they become virtually noise-free like an audio CD, with terrific dynamic range. Huge enlargements become possible because there is no grain or noise to spoil the show. Problem solved!  :D
Title: The Missing Factor in Sony F828 Reviews
Post by: BJL on February 02, 2004, 12:07:54 pm
About the resolution of larger format versus smaller format lenses, what testing like that at photodo sems to show is that

a) larger format lenses have somewhat lower resolution in the technical sense of fewer "line pairs per millimetre" in the image formed in the camera

 however, the larger format leads to more detail in the sense of "line pairs per picture height", which translates in to more "print resolution" in the sense of more line pairs per millimetre on prints of a given size.
Title: The Missing Factor in Sony F828 Reviews
Post by: BJL on February 02, 2004, 12:41:22 pm
Quote
To further illustrate this point, the Olympus E-1 would be an excellent example because the Zuiko lenses appear to be so much better than the rather noisy and low resolution 5MP sensor.
Ray,

   first, I have asked indirectly before but am still curious: how do you come to your conclusions about the resolution and noise performance of the E-1? By reading lab. test results only, or also by actually looking at properly prepared prints? I have heard mostly favourable comments from peope judging from prints. The letter from Mike Sims mentioned in the What's New section ( http://luminous-landscape.com/essays/cogna....shtml#feedback (http://luminous-landscape.com/essays/cognative.shtml#feedback) ) seem apposite.

    Secondly, the one part of your proposal that I think has the most chance of coming to pass is photosite sizes of 4 microns and even below 3 microns in many DSLR sensors, not just 4/3 format. This is because, once those huge numbers of pixels can be read out and processed fast enough, there is almost no image quality downside to having more, smaller pixels in a given sensor size:

a) Printing at the same size and hence with proportionately higher ppi levels effectively downsamples, which recovers roughly the same visible noise levels, dynamic range, tonal gradations and such as if one had had fewer pixels to start with: prints of the same size from a sensor of the same size and technology should show roughly the same image quality as photosite size shrinks, except for increased resolution in regions where noise does not interfere.

 For subjects of normal contrast range with adequate light levels, photosites of around 3 microns have already been shown to give quite good image quality, with competely satisfactory noise levels, so you would often be able to expolit the greater resolution by making larger prints. (The new book "America 24/7" shows what pros can do with the 2.8 micron photosites of the 5MP 1/1.8" sensor in the Olympus C-5050.)

c) Often there would be visible noise in some regions (shadows) but not others (main subject), and then noise reduction post-processing could fix the shadows (at some resolution cost there) while maintaining higher resolution in the better lit parts.
Title: The Missing Factor in Sony F828 Reviews
Post by: Ray on February 02, 2004, 10:25:28 pm
Quote
That makes perfect sense to me, and was so obvious that it is hardly worth mentioning in the first place.
There are many things that seem obvious after the thought has occurred, including Darwin's Theory of Evolution.  :D

The lack of development of large and medium format gear has been apparent for a long time. To the camera buying public, the cost of such gear has always seemed outrageous. The cost of MF digital backs is even more outrageous.

There's a very high price to pay for that additional image quality, so don't be surprised if these dinosaurs become extinct.

A true digital sensor will seal their fate.  :(  
Title: The Missing Factor in Sony F828 Reviews
Post by: Ray on February 04, 2004, 08:10:57 am
Quote
I'll see if I can set one up, but I can assure you that there will be no comparison in depth of field.
Lin,
How about the following comparisons?

(1) the F828 at ISO 100 and F8, and the 10D at ISO 400 and f13.

(2) the F828 at ISO 64 and F8, and the 1Ds at ISO 800 and F32?

Same exposure, same DoF and equivalent focal length in each case. This would represent a true level playing field and would let us all know just what the F828 can do that these other DSLRs can't.  :D
Title: The Missing Factor in Sony F828 Reviews
Post by: BJL on February 04, 2004, 06:34:15 pm
Quote
How about the following comparisons?

(1) the F828 at ISO 100 and F8, and the 10D at ISO 400 and f13.

(2) the F828 at ISO 64 and F8, and the 1Ds at ISO 800 and F32?

Same exposure, same DoF and equivalent focal length in each case.
Where do you get your 10D f-stop value of f/13? The 10D sensor is larger than the 828's by a linear factor of about 2.5, and its photosites are larger by an even larger factor (in case one compares by cropping to equal pixel counts) so the comensurate f-stop for the 10D should be about f/20, and hence ISO speed a bit over 600.
Title: The Missing Factor in Sony F828 Reviews
Post by: BJL on February 09, 2004, 03:54:59 pm
Quote
Is there a general rule to get the number of electrons caused by a single photon (I remember a mean efficiency of about 30%)?
Any hints are appreciated.

Georg
Thanks for that number; I have been trying to infer that value from data for particular sensors, but get only about 4,000 electrons for the 6.8µm^2 photosites of the E-1 sensor, and so about 15,000 photons assuming that "Quantum Efficiency" (electrons per photon) of about 30%.

That quantum efficiency figure of about 30% is about right though, according to Kodak's spec sheets, which are a good place to look. It is also close to the maximum possible for colour photography, when you remember that each site should only respond to light in the correct part of the spectrum.
Title: The Missing Factor in Sony F828 Reviews
Post by: Howard Smith on February 19, 2004, 03:28:00 pm
Ray, you say complex organisms evolve very slowly over millions of years.  Let's look at but one thing required for human life - hemoglobin.  Not an optical system, but one component of blood.

Using the formula for the linear arrangement of amino acids to make hemoglobin, there are about 7.4 X 10(654) combinations.  (Not a bad approximation of infinity.)  Keep in mind that ONE misplaced acid is usually fatal.  Sickle cell anemia is an example.  And each time you combination fails and theorganism dies, you have to start over.

Now try to imagine 10(500+) random trialsto evolve just hemoglobin.  The accepted age of the universe is about 10(17) seconds.  So you would have to try about about 10(480) combinations per second.  That's a lot of megahertz!

There ar about 10(66) atoms in the universe.  Not much material to waste evolving hemoglobin.

There doesn't seem to be enough time or material to make hemoglobin by chance.  You need a lot of external help.  A Designer or Creator.

One might argue that a computer could evolve naturally.  But without software, the computer is pretty lame.  Where do evolutionists claim "information" came from?

The gurus of evolution aren't about to admit there precious theory is in real trouble.  It takes a lot of commitment to fallicies and blindness what is around you to be an atheist.  Just as I cannot "prove" there is God, you cannot prove there isn't.  I am not willing to gamble eternity on the arrogant assumption there isn't.
Title: The Missing Factor in Sony F828 Reviews
Post by: BJL on February 06, 2004, 09:24:40 am
Ray,

    thanks for the link on read noise; yes read noise increases with read rate, and the 5 electron figure is for the extreme case of very slow read out (40kHz, meaning 25 seconds per MP?) from a sensor with huge photosites. Even the 1MHz read rate for the case with 11 electrons is way below what digital cameras need, since I think that 5MP @ 3fps needs 15MHz. I will search for some more up-to-date read noise information; I think Dalsa has a graph of read noie vs read rate at their web site, relating to their 22MP FFT CCD for medium format backs.
Title: The Missing Factor in Sony F828 Reviews
Post by: Howard Smith on February 09, 2004, 01:10:57 pm
So, ae you saying that smaller isn't better?  Maybe bigger could be better?
Title: The Missing Factor in Sony F828 Reviews
Post by: georgj on February 10, 2004, 04:39:05 am
Hi BJL,

thanks for your answer, it makes me feel a bit more comfortable with my 'homebrewn phisics'.
In 3 µm sensors, even if you leave the read-out-error and thermal noise aside and thus go down to abt. 100 electrons or 300 photons (giving a 10/1 S/N-ratio), you'll have roughly 500 distinguishable steps of intensitiy (by dividing the [18,000;300] interval in classes that are half wide the mean error (e.g. 18,000; mean error 134; next step is 17993, class width decreasing continously). Of course, one might add some more steps at the top end towards maximum so that a 100% reflectivity wouldn't blow out.
What did I learn? I come to about 6 f stops dynamic range; one cannot read information from the sensor without enough photons; I still want the F828 ;-).

Thanks, Georg
Title: The Missing Factor in Sony F828 Reviews
Post by: on February 15, 2004, 11:38:08 pm
I can hardly wait for Michael tp use the new test equipment - DxO I think it is called.  It will be wonderful to have real information.

And the lens correction program - if they make it available for enough lenses -will be worth a great deal.  I expect by next PMA that most top-end prosumer digicams like the 828 will have this built into the software, and problems like CA and PF will be quaint relics of the past...

It should be possible to put it in DSLRs, I guess, since the DSLR has to know which lens it is using anyway, and should be able to apply the correction for that specific lens.  

This whole thing should really finish film for keeps since there IS no software in a film camera and corrections could only be applied after scanning....

Like MR says, everything is about to change....

willie
Title: The Missing Factor in Sony F828 Reviews
Post by: Howard Smith on February 18, 2004, 03:19:20 pm
Ray, there is considerable difference between agnostic and atheist.  I believe there is God, and know I can't prove it.  I guess I may be an agnostic too, accepting God on faith.  If God could be "proven," we would all believe in God.

BJL, why can't a debate of God be rational?  And isn't the "totality of informed assessment of the evidence and arguments" simply the summation of all the opinions of individuals?  I really don't whether Darwin believed his theory or not.  I have examined the evidence and find evolution to quite impossible.  If one takes the Bible seriously, one would also deny evolution.

Probably enough said.  Back to photography.
Title: The Missing Factor in Sony F828 Reviews
Post by: Ray on February 19, 2004, 06:42:47 pm
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Ray, you mentioned that the Pope is not an "evolution denier."
No, that was BJL  . The history of persecution of rational, clear thinking individuals (such as Galileo) by the Church is a disgrace and has done great harm to the Christian movement, and that's a great pity.

However, I think it is possible to have a belief in God and accept the Evolutionary process. It just requires a bit of reinterpretation of the Bible. A day of the 'six days of creation' then becomes 4.8 billion divided by 6, and the process of evolution then becomes the method which God has used to create the universe. He's set the laws in motion and allowed things to happen and fall where they will (sort of thing  :D )
Title: The Missing Factor in Sony F828 Reviews
Post by: Ray on February 19, 2004, 07:51:57 pm
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Ray, the brown moth thing is bunk.  It was later discovered that the spotted moth does not rest on tree truncks or branchs.  The moths used to support that rot were dead and glued or pinned to trees to prove the theory.

Can you give me some sources for this information? My source is Richard Dawkins.

Quote
I'm also confused about why you care about the "Christian movement."  I am laboring under the opinion you are an atheist

First of all, I make a distinction between "disbelief in God" and "belief that God does not exist". The former is passive and the latter is active. The terms Atheist and Agnostic are fairly rigid categories. To state one's true position, one is up against the limitation of language. Putting myself in the category of 'agnostic' seems a bit wimpish. Putting myself in the category of 'atheist' seems a bit foolish, so what can I say?  :D

I care about Christianity because it seems clear the true Christian view of the world, with its origins in Judaism, is actually favourable to scientific enquiry. Neither the ancient Greeks nor the Arabs who gave us our numer system, really caught on to the scientific process. There's something about the Judaic view of the world that has allowed the development of science, despite occasional ignorant outbursts of persecution by the Christian church.
Title: The Missing Factor in Sony F828 Reviews
Post by: A Scottish soul on February 20, 2004, 08:13:52 am
OOps

my mistake  it is a 14 bit counter not a 13 bit.


John
Title: The Missing Factor in Sony F828 Reviews
Post by: Ray on February 20, 2004, 09:47:31 am
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I am sure that believers in God are not foolish like atheists.  For a second, let's assume I am wrong - there is no God.  What harm have I done myself or anyone else by living the life of a believer?  But the long term harm for the atheist and the agnostic is unspeakable if they a wrong.  When you meet God, are you going to be provocative and deny Him?  Might as well.  It will too late to embrace Him.
Well, I'm certainly no judge of what harm you might have done yourself or anyone else by living the life of a believer, but I've read lots of stories of people who claim to believe in God, and yet appear from my perspective to do lots of harm to themselves and others. The Old Testament has many examples of believers doing great harm to each other.
Title: The Missing Factor in Sony F828 Reviews
Post by: Ray on January 22, 2004, 11:37:47 pm
In that case, what's all the fuss about? I don't have the camera to play with, but even Mattew Cromer seems concerned about CA.  He even returned the camera for an exchange, as have others, so I believe.
Title: The Missing Factor in Sony F828 Reviews
Post by: Ray on January 23, 2004, 05:45:47 pm
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One suggestion at Norm Koren's site is that lens abberations starts to be the dominant factor in image quality at f/4 and wider, and he implies that this is an inherent limitation in optical design (dealing with coma, spherical abberation and all those other things that I know little about except their names).
Makes sense! There seems to be no hard and fast rule on this. I have some vague memory of a review of a Leica Summicron 50mm lens (or maybe it was a Carl Zeiss lens) that displayed its best performance at full aperture F2.8. I think there's at least one Canon lens that performs best at f4. However, the Canon 100-400 IS zoom, at 400mm, is sharpest at f11 which is exactly 2 stops down from full aperture.

I have some Sigma lenses which appear to be sharpest at about 4 or 4 1/2 stops down from full aperture  :D .

If we were to assume that the F828 Zeiss lens is sharpest at f5.6, then the fall-off at f8 is likely to be negligible, which would make the F828 an ideal camera for all those shots that require great depth of field.

No CA, great DoF and close to maximum sharpness. Why is no-one shouting about this?  ???
Title: The Missing Factor in Sony F828 Reviews
Post by: Ray on January 24, 2004, 10:18:05 am
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Who needs great (or greater) depth of field at focal lengths of 7 - 50 mm?
Who needs anything? What's your point? The pinhole camera is famous for its DoF, but the quality is lousy. I'd use F22 more often with my D60 if the resolution wasn't seriously compromised.

The resolution of the F828 seems to be on a par with that of the D10. But at what aperture? Resolution varies with aperture. Depth of field varies with aperture. Depth of field also varies with camera format, at any given aperture.

See the problem?
Title: The Missing Factor in Sony F828 Reviews
Post by: BJL on January 26, 2004, 11:43:39 am
Probably DOF equivalencies are not quoted because there is considerable ambiguity about how one should compare. Two common options are (a) compare DOF as seen on prints of the same size and shape, viewed from the same distance, and ( compare DOF on the biggest prints that are consistent with the resolution that one expects from the sensor (including film emulsions as chemical sensors), again assuming the same minimum viewing distance, at least when details are being scriutinized.

   Case (a) leads to the guideline of having the same DOF with the same aperture diameter, or in other words, scale the f/stop in proportion to the chosen focal length: the lens of the 828 compares to a 28-200, f/8-f/11.

   However, case ( is perhaps more common in the film world, where people sometimes think in terms of the DOF requirements of prints at a maximum enlargement factor of about 8x (a 12"x8" limit for 35mm format and so on), so making larger prints from larger formats, and allowing for people sometimes viewing them from the same minimum distance despite the larger print size.

   At that extreme, the rule is that the DOF is dictated simply by the actual focal length and aperture, regardless of image format.

    With digital cameras, this comparison only makes easy sense if the pixel pitch is the same despite the different formats, but maybe a rough digital counterpart would be to work on the basis of printing at 300PPI and computing the DOF that one would then see when viewing from 10", which is about the distance that good human eyes need to be at to resolve 300PPI.

   I think that the guideline then becomes that one scales the f/stop in proportion to the pixel pitch (or to the resolution of the sensor/lens systems being compared, measured in lp/mm) when comparing DOF at maximum usable print size.
Title: The Missing Factor in Sony F828 Reviews
Post by: BJL on January 26, 2004, 06:30:18 pm
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Depth of field is a function of f/stop, focus distance, and the acceptable circle of confusion size.  Period.  It has nothing to do with film/digital/format.  Again I suggest you read Michael's tutorial on Understanding Depth of Field.
Here we go again: format size DOES matter in DOF calculations because the circle of confusion size has to be adjusted for different format sizes: in the end, the CoC diameter that counts is the one on PRINTS after considerable enlargement from the CoC size formed in the camera, and images from a format like a 2/3" digicams with sensor diagonal of 11mm are typically going to be enlarged far more (about for times as much) than ones from a 35mm format sensor (diagonal 43mm), so the circle of confusion in the image formed in the camera needs to be far smaller (about 1/4 as much) than that used in DOF computations for 35mm film.

   One hint of this is to look at the CoC values chosen for various formats in a DOF calculator like the one at
http://dfleming.ameranet.com/dofjs.html (http://dfleming.ameranet.com/dofjs.html)
Change the format choice and see how the recommended CoC diameter adjusts.

    As another exercise, try changing from 35mm format, focal length f=80mm, aperture ratio f/16 to Sony 828, f=20mm (roughly the same angular FOV), f/4 (same aperture diameter of 5mm in each case), keeping the same focal distance. You will see that the near and far focus distances are about the same, whereas if you keep the f/stop at f/4 in each case, they are wildly different.
Title: The Missing Factor in Sony F828 Reviews
Post by: Ray on January 26, 2004, 10:44:23 pm
Next exercise; read my previous posting.  :)
Title: The Missing Factor in Sony F828 Reviews
Post by: Howard Smith on January 27, 2004, 09:57:16 am
First, depth of field and format have no relationship.  The lens simply has no way of knowng what's behind it.  Depth of fieldhas nothing to do with resolution.

Yes, depth of field calculators do use different size circles of confusin for different formats.  You should read the fine print to understand why.  The reason is smaller faromats are usually enlarged more than larger formats.  An 8x10 contact is much easier to see than a 35 mm contact.  The calculators assume the user is using a lens of appopriate focal length.  That is why a "normal" 35 mm lens is about 50 mm, a "normal" 6x6 lens is about 80 mm, and a n
"noral 4x5 lens is about 150 mm.  Put a 150 mm lens on a 35 mm camera and you will get the same image size as a 4x5, just cropped rather severely.  Set bot lens at f/whatever, and you get the same depth of field when making a print with the same image size.

It appear that non of us re going to give up our positions, so let's just agree to disagree and go on.
Title: The Missing Factor in Sony F828 Reviews
Post by: BJL on January 28, 2004, 10:04:59 am
Ray,

    I generally agree about comparing performance mostly with comparable angular field of view, depth of field and shutter speed, to most closely match the overall "composition", but with two small disclaimers.

a) Michael's assessment of the 828 might have been primarily aimed at deciding whether it is "good enough" for use as a more compact, lightweight alternative to the 1Ds kit in some situations, rather that a head-on "which is better?" comparison to the 10D; his testing seem fine for establishing that he can forgo the bulkier intermediate option of the 10D in many situations.

 As to the different question of "which is better?", there is also a place for comparing at the apertures determined to give best overal image quality; maybe f/5.6 is a decent first guess for many lenses, due to abberation problems that arise at apertures of f/4 and larger, more or less independent of focal length and format. I am sceptical of the dogmatic "two stops down from maximum", and note that Norm Koren makes the vaguer statement "2 to 4 stops" in his ineresting discussion at http://www.normankoren.com/Tutorials/MTF6.html#Sweet_spot (http://www.normankoren.com/Tutorials/MTF6.html#Sweet_spot)

   But this is rather speculative. I would be very interested to see tests of abberation effects on image quality in various lenses at their larger apertures, since optical theory is so much more complicated and less illuminating for abberation than the formulas for circle of confusion and diffraction spot size (Airy disc diameter.)
Title: The Missing Factor in Sony F828 Reviews
Post by: BJL on January 28, 2004, 05:54:53 pm
The approaches suggested by Ray and Howard both make sense to me, according to which aspect of camera performance one is assessing. How about distinguishing the following cases?

a) No shortage of light, assessing ultimate image quality (like tripod shots with no moving subjects, or hand-holding in bright enough light): set each camera to its optimum ISO rating (usually the lowest) and each lens to its optimal aperture: let the shutter speed fall where it may.

 Light availability limited by shutter speed limits (due to subject motion and/or hand-holding) and also the need for adequate DoF: exposure time and aperture diameter are limited to about the same maximum, so adjust ISO speed setting as needed.

c) Light availability limited by shutter speed limits as above, but with no particular DoF needs: test at the same shutter speed, with each lens at its widest usable aperture, and again adjust ISO speed setting as needed. ("Widest usable aperture" might exclude a lens's maximum aperture if that leads to problems like the dreaded purple fringing.)

P. S. want to redo this whole debate with the next 8MP 2/3" format digicam, the Nikon 8700 with is 8.9-72mm [35-280 equiv.], f/2.8-4.2 lens?
Title: The Missing Factor in Sony F828 Reviews
Post by: Ray on January 28, 2004, 10:57:24 pm
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Call me old fashiond (I am)
Well, you've said it.  :D  I wouldn't strenuously disagree with you.  :D

The paradigm is changing and I don't think any of us really knows what the future will bring. But there seems to be a trend towards the smaller format equalling the quality of larger format, with digital.

The 1Ds, for all practical considerations as far as Michael is concerned, equals the image quality of the Pentax 6x7, and the F828 more or less equals the quality of the 10D (but not feature wise), with a bit of help from noise reducing programs.

I find it difficult to get my mind around the significance of the competing issues and trade-offs. How much can sheer numbers of pixels compensate for lack of size? How good can these short focal length lenses really be at f2 or f2.8? What are the relative economics of producing a smaller format with the same image quality as the (usually) more expensive larger format?

These are questions to be considered.
Title: The Missing Factor in Sony F828 Reviews
Post by: Ray on January 30, 2004, 02:07:31 am
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Unless quantum mechanics has changed a great deal since I was in college, I think I can understand and appreciate the subtle difference betwee digital and analog.
Howard,
I believe you understand the diffefrence between digital and analog, and I think I more or less said so in my previous post. Sorry if you've misinterpreted my comments.

Nevertheless, you do not seem to have understood the significance of a truly digital camera. All the current debate on noise, as it applies to small format cameras in relation to large format cameras, is essentially an analog problem. We don't actually have any digital cameras. They're all analog cameras with 'attendant' digital functions that result in a digital output.

As Moore's law continues to apply, and I'm assuming here that it will, 10GB images will eventually present no processing problem. When this situation arrives, the stage will be set for a true 'digital' camera with no discernible noise, and a dynamic range of 20 f stops. The large format (and medium format) camera then becomes a total irrelevance; no more than a museum piece. That's the point I was trying to make.

Okay! Still friends?
Title: The Missing Factor in Sony F828 Reviews
Post by: Howard Smith on January 30, 2004, 04:17:19 pm
BJL, no, I have no proof or evidence.  I should have stated that as opinion based mostly on Canon finally making a full frame 35mm.  That camera seemed to eagerly awaited and overdue.  Canon may have had motvation to make a digital body that could use their rather complete line of 35mm lenses to best advantage, rather than introduce all new lenses.  But then Nikon should be similarly motivated - both to keep up and use their existinglenses for now.

Because Nikon and Canon arre not currently players in medium or large format, I wouldn't expect then to introduce a new camers line.  Of course, I was surprised when Hasselblad brought out the X-Pan line.  I would expect that Hasselblad will make an effort to have a digital back for there current medium format camera line.  They have always prtty good at keping the old 500 alive.
Title: The Missing Factor in Sony F828 Reviews
Post by: BJL on January 31, 2004, 01:37:17 pm
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BJL, no, I have no proof or evidence.  I should have stated that as opinion based mostly on Canon finally making a full frame 35mm.  
Perhaps this is mostly a confusion over tense, past versus present. Clearly there has was for a long time a need to develop larger sensors, because to some degree greater size has advantages. (However, my crude analysis of how noise levels vary with sensor size, aperture and exposure time suggests that the advantages hold under more limited circumstances than many believe, requiring adequate light levels and/or decreased depth of field if resolution and/or dynamic range is to be improved over what smaller sensors can achieve. The failure of the three "full frame" DSLR's to show better overall low light performance than the APS models with sensors less than half as big corroborates this.)

   I was talking of the present situation, where sensor size growth seems to have mostly or completely stopped (especially with digicams, where it stopped years ago). Since you mention Canon, they are an interesting case; the 1D Mark II does not, as widely predicted, move up to full 35mm format but instead stays at the same size as the 1D (or is there a very slight increase?); the amateur level sequence of D30/D60/10D/300D has shown no sign of increasing sensor size, but instead just one decrease in photosite size, accompanied by an improvement in noise levels.
Title: The Missing Factor in Sony F828 Reviews
Post by: Howard Smith on February 01, 2004, 04:00:16 pm
Ray, I was not aware that large format lenses have superior resolution than 35mm lenses.  In fact, I have always thought just the opposite.  And I also thought that the resolving capability of, say, T-Max 100 was the same whether it is 35mm, 6x6 or 4x5.

I always thought that the advantage of large format was not its lens, but the fact that a great deal of the enlarging is done at exposure time, so the negative need not be enlarged as much to make a print.
Title: The Missing Factor in Sony F828 Reviews
Post by: Howard Smith on February 02, 2004, 08:56:05 am
OK, I think I have it.

If you can make a small sensor digital camera that is better than a current large format film camera and don't bother to improve the current large format camera, you will have a small format digital camera that is better than the current large format cameras.

That makes perfect sense to me, and was so obvious that it is hardly worth mentioning in the first place.
Title: The Missing Factor in Sony F828 Reviews
Post by: Lin Evans on February 02, 2004, 05:03:12 pm
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No CA, great DoF and close to maximum sharpness. Why is no-one shouting about this?  

They really should be. The thread has strayed a bit from the original question, but the F828 is exceedingly sharp at F8. I shoot gallery art for a living, and there are times when I'm using one of my several dSLR's or my Kodak MF back when I simply long for the incredible DOF offered by the small sensor digicams which capture DOF and sharpness with ease which is downright difficult to achieve with my conventional film or digital SLR's.

The F828 has offered the first truly useful compromise which I can actually use professionally for those times when I really don't want to spend all day trying to achieve the DOF and "look" I want from my images. Because of it's increased resolution over the present digicam field (Nikon's offering not yet tested), I find I can get quite suitable 16x24 prints with near perfect color match and incredble sharpness, especially when doing relatively close-up work.

Here's a quick sample of a Jon Anderson original polymer art piece (about 3 inches long) at reduced size (800x600) and a link to the full sized, slightly cropped version. ISO 64, F8, full tele (51mm true - 200mm equiv) 1/400th

Lin

(http://lin-evans.com/f828/horntoads.jpg)

http://www.lin-evans.com/f828/horntoadb.jpg (http://www.lin-evans.com/f828/horntoadb.jpg)
Title: The Missing Factor in Sony F828 Reviews
Post by: Ray on February 04, 2004, 08:37:06 am
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The worse S/N ratio and dynamic range of more numerous smaller individual pixels is exactly balanced by the greater number of them used to print each given portion of the final image.
BJL,
You've made this concept very obscure by setting so many convoluted conditions.  

As I understand it, there are three broad types of noise; photon noise; dark noise and read noise. It's the additional read noise (the process of quantifying the electronic signal) which might be unavoidable if one substitutes fewer bigger pixels for a lot of smaller ones.

For example, let's suppose that Canon were to replace the 10D with a 12MP model, keeping the sensor the same size, the design principles and quality of components the same and the noise reduction processes the same etc., then the total read noise in the entire image would have essentially doubled, would it not?
Title: The Missing Factor in Sony F828 Reviews
Post by: BJL on February 04, 2004, 06:25:37 pm
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BJL,
You've made this concept very obscure by setting so many convoluted conditions.
My apologies: which conditions were convoluted? There were really only three:
a) Comparing sensors of the same size and technology (e.g. Sony's 2/3"  CCD's at 5MP and 8MP)
 Comparing images of same size rather than the widespread nonsense of comparing files of different MP counts at 100% pixel size on screen
c) not going to photosites so small that a larger fraction of the sensor surface is occupied by stuff other than electron wells, reducing highlight headroom.

   Only the last seems convoluted, but it simply recognizes one of the practical limits on photosite miniaturization.
Title: The Missing Factor in Sony F828 Reviews
Post by: Ray on February 05, 2004, 07:45:34 pm
Quote from: BJL,Feb. 05 2004,13:50
Can you give me a source for that "Read Noise figures as low as 5 to 11 electrons for CCDs with a full well capacity of 45,000 to 375,000 electrons."?  Because if it means "5 for 45,000 and 11 for 375,000", then there is a considerable reduction of read noise with pixel size, very close to my beloved square root pattern.
BJL,
Actually, it's the other way round. The larger read-noise figure relates to the smaller photodetector. This appears to be due to the frequency of the read rate in the two examples chosen. The higher the sampling frequency, the greater the read noise.

I can find no information on Roper's site that expresses a relationship between physical pixel size and read noise. The two examples I quoted can be found at:-

http://www.roperscientific.com/library_enc_dynamic.shtml (http://www.roperscientific.com/library_enc_dynamic.shtml)

[/QUOTE](Do you really believe that CCD's are old hat and that most or all present progress is in the CMOS world? If so, explain it to all the digital back makers, and to Fuji, whose SuperCCD is the high resolution, low noise measurement leader in the APS DSLR field.)
Quote

Hey! What do I[/i] know!  :D  I'm just an ordinary guy with a few scraps of information and a few half-baked ideas trying to fill in the enormous gaps.  :D

CMOS just seems better positioned to take advantage of the rapid development in nanotechnology and chip manufacturing processes used by companies such as Intel. As it becomes possible to manufacture increasingly smaller components, you could end up having a whole 'city' of operations within that one 4 micron photosite.  :D
Title: The Missing Factor in Sony F828 Reviews
Post by: BJL on February 09, 2004, 02:01:39 pm
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So, ae you saying that smaller isn't better?  Maybe bigger could be better?
Howard,

    it should be clear that my consistent opinion is not a mindless, partisan "smaller is better" or "bigger is better", but a weighing of advantages in each direction. Specifically, I have repeatedly argued that (i) larger sensors have some clear advantages in ultimate attainable image detail, when enough light is available (with digital as surely as with film), but that (ii) the advantages have often been misinterpreted and overstated, particularly by ignoring depth of field needs, increased thermal noise in the longer exposures typically needed with larger formats, etc., and  (iii) the cost and weight savings of smaller formats can in practice improve image quality for most photographers, by allowing them to buy and carry more and better quality lenses.

   When I weigh the factors, instead of looking at arguments on one side only, I come to the same conclusion as is indicated by the actions of every camera and sensor maker: (a) a sensor format of 2/3" or smaller is optimal for the great majority of photographers, including the moderately serious ones now being targeted by new 8MP, 2/3" models from no less than four major manufacturers, and ( even within the far smaller SLR market,  the optimal sensor size will be in the smaller 4/3" to "1.5x" range. (I also expect that this severe numerical disadvantage in demand will therefore keep the economies of scale poor for larger formats like 35mm DSLR, so that they will probably never drop below the price range of professionals and very serious amateurs.)
Title: The Missing Factor in Sony F828 Reviews
Post by: BJL on February 09, 2004, 04:08:59 pm
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something I forgot... 18,000 photons resulting from a bright (isotrope) reflecting white surface.

Georg
Meaning 100% reflectivity? I hope so, because then our numbers are in agreement: for standard 18% reflectivity the number becomes about 3300 photons and so about 1000 electrons, or a bit over 100 electrons per square micron, matching close enough to the 92 eletrons per square micron from E-1 sensor data.

    This has a consequence for maximum attainable sensitivity (ISO speed) based on adequate shadow region quality: to get a decent minimal S/N ratio of 10:1 (a Kodak recomendation) in shadow areas needs at least 100 electrons, and for 3 square micron pixels at ISO 100, it seems that this would occur a bit more than three stops below "18% gray", about the low limit aimed at for decent shadow detail. So about ISO100 might be the upper speed limit for 3micron photosites, ISO400 for 6 square microns, ISO900 for the 9 microns of current high end sensors, and so on. (Higher ISO speeds on DSLR's must be "elecronic push processing", lower values are possibly "pull processing", with better shadow handling than ISO film speed standards require.)

P. S. and at most about ISO 80 for the 2.7 square micron photosites of Sony's 8MP 2/3" sensor, fairly close to its observed behaviour given how crude this reckoning is!
Title: The Missing Factor in Sony F828 Reviews
Post by: Ray on February 09, 2004, 06:39:55 pm
Look, you guys! I sense a deep confusion amongst at least some of you (not naming anyone  ) and the seeds of this confusion have been sown by the Sony marketing department. The confusion lies in the nomenclature.

The Sony F828 is either a 7-50mm, F2, ISO 50 (64?) camera, or it's a 28-200mm, F8, ISO 800 camera, but not both. You can't have your cake and eat it. Unfortunately, that's what most of us like to do (have our cake and eat it) and Sony have capitalised on this, as do all other makers of small format cameras. (Can't blame them, I suppose.)

As a consequence of this mixing of terms, according to how attractive the numbers will appear to the consumer, there's a widespread impression that small format cameras are 'necessarily' low resolution and noisy.

It's this misconception that I'm questioning in this thread. Small cameras are noisy, not because they are small but because they are effectively (in 35mm terms) very high ISO cameras.
Title: The Missing Factor in Sony F828 Reviews
Post by: BJL on February 18, 2004, 01:29:00 pm
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Ray, I didn't say Darwin became a Christian.    He simply realized that his theory of evolution was fatllly flawed - was not correct.  One does not have to be a Christain to beleve Darwin was wrong.  
We are getting way off topic, but I think it is more to the point to say that one does not have to be an "evolution denier" to be a Christian (for example, the Pope isn't).
    Stories of Darwin deciding that his theory of evolution was fatally flawed are nonsense: he knew that there were details needing to be explained, some of which relied on the discrete nature of genetics and inheritence discovered later by Mendel, but "unfinished" is very different from "wrong".

   Anyway, attacking the credibility an idea on the basis of the alleged opinions of its original author is an "authoritarian" approach, maybe appropriate to religion but certainly not to science: in science, and all rational debate, the totality of informed assessment of the evidence and arguments over time is what counts, not the opinion of any one person.
Title: The Missing Factor in Sony F828 Reviews
Post by: Ray on February 18, 2004, 07:54:33 pm
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So what about the 1 in 1000?  Well, suppose an organism evolved a complete eye on its forehead.  A pretty neat trick in itself since the eye is a rather complex organ.  But unless that eye also has an optical nerve and a site in its brain to process the information and understand what it is seeing, the new eye is worthless.  The mutated eye will disappear in futre generations.  The entire optical system would have to evolve in one step.  Never happen.  It is similar to a tornado going through a junk yard and leaving a fully assembled CAnon 1Ds with a 17-40mm zoom in its path.
Since no-one is listening except Digi-T, I suppose we can have a quiet conversation amongst ourselves, and after all, the eye is related to photography  :D .

Howard, with all due respect, you're quoting the most obvious of religious propaganda. Any Jehovah Witness manual will use that argument to debunk Evolutionism.

The fact is, nobody believes that's how Evolution works. Mutations play a role, but complex arganisms like the eye, evolve very, very slowly over hundreds of millions of years and the stages of such evolution can be seen in the enormously wide variation in the sophistication of the eye in various creatures, from half blind worms and eyes so primitive that we'd hardly recognise them as eyes, to our own marvelous organs.
Title: The Missing Factor in Sony F828 Reviews
Post by: Howard Smith on February 19, 2004, 11:44:05 pm
For information on the moth myth, see "Icons of Evolution" by Jonathan Wells, or maybe a newspaper article by Jonathan Wells.  I don't remember exactly which, but it was Jonathan Wells.

I got the idea you were an atheist from your post on Rejecting Yosemite, January 30, 2003.  You said, "I am an Atheist."  Atheism is quite foolish.  Agnostic is wimpish.

An agnostic believes there can be no proof of the existance of God (and I believe that too) but does not deny he possibility that God exists.  An atheist denys the existance of God.  I claim that the atheist cannot prove his position, but must take that position on faith - just like a believer in God.

Some Christians do believe in evolution.  While that belief is not supported by the Bible, I don't think it disqualifies one from being a Christian.  However, not taking the Bible seriously can be very dangerous.  It is easy to be deceived when you seek explainations from the secular.  Ray, keep an open mind to the exisance of God.  Just look around you next time you are out photographing God's creations.  It is truely wonderful and could not have happened by chance.
Title: The Missing Factor in Sony F828 Reviews
Post by: Ray on February 20, 2004, 09:12:22 am
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Instead of using the 256 micro sensors, which are still analog by design, just use one and use it to count photon strikes via a digital counter capable of counting up to the 15000/3 layer = 5000 photons expected for a bright day or more to add extra dynamic range. This would be a 13 bit counter giving 8192 levels ov brightness.  Then you would have a 100% digital system with unlimited dynamic range, depending on the max value possible in the counter. The digital value in the counter would then be read out after the exposure. Speed of operation of the counter would be key to its possibility and also squeezing the small detector and counter registers into a 4u square area. This is unlikely at the pressent but who knows what the nano technologists may be able to do on silicon in the not to distant future!
Sounds a lot less cumbersome than my idea  :D . But I really haven't much idea how practical such an arrangement would be. How big are digital photon counters and how fast can they count? I tend to think they're rather large instruments and/or would be easily overwhelmed by large amounts of light. I mean, those photons are not arriving in a nice orderly manner, one after the other  :) .
Title: The Missing Factor in Sony F828 Reviews
Post by: Lin Evans on February 03, 2004, 07:45:54 am
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Thanks for posting that vibrant and spectacular shot of the painting. All we need now is a comparison between the F828 at f8 and the 10D at f13, of a highly detailed subject with the exposure the same in both cases.

I'll see if I can set one up, but I can assure you that there will be no comparison in depth of field. I frequently shoot art of this type with my 1DS, and sometimes with my 1D and 10D and I can't get the DOF with any of my dSLR's that I get with the F828. Typically I shoot at between F11 and F16, but I would need to go to F32 to get equivalent DOF and the sharpness just isn't there at the super small apertures.
Title: The Missing Factor in Sony F828 Reviews
Post by: georgj on February 10, 2004, 04:06:50 pm
Hi BJL,

you're right with the intervals mentioned based on a very high accuracy for finding the respective intensity class; I've allowed a certain overlap resulting in ~460 steps on the basis of a better than 2/3 chance for identifying the correct part of the interval (the mean error equals sqr(n) but is not equally distributed).

Georg
Title: The Missing Factor in Sony F828 Reviews
Post by: Howard Smith on February 19, 2004, 06:40:01 pm
Ray, I certainly don't know you are right.

For natural selection to work, the mutation must be beneficial or attractive for the organism - give it an edge.  Given the time available to "test" the mutation and the fact that most mutations are fatal or non-beneficial, seems impossibe for evolution to work.  You know that.
Title: The Missing Factor in Sony F828 Reviews
Post by: on February 20, 2004, 10:23:24 am
This thread has really strayed from its origins. And since we are now firmly treading in the area of religion, and this is a photography-related site, I'd like to suggest that this discuss either be continued in private or dropped.

Like at the dinner table, religion, sex and politics are best avoided here.

Michael
Title: The Missing Factor in Sony F828 Reviews
Post by: Laco on January 23, 2004, 03:56:10 am
Lenses have normally their best performance at 2-3 f-stops from being wide open. After that their performance slightly decreases.
Title: The Missing Factor in Sony F828 Reviews
Post by: Howard Smith on January 26, 2004, 06:06:58 pm
Depth of field is a function of f/stop, focus distance, and the acceptable circle of confusion size.  Period.  It has nothing to do with film/digital/format.  Again I suggest you read Michael's tutorial on Understanding Depth of Field.
Title: The Missing Factor in Sony F828 Reviews
Post by: Howard Smith on January 26, 2004, 11:40:12 pm
Ray, I re-read your last post.  But don't forget, if you reduce the focl length of the ense to get great depth of field, youalso reude the image size.  The image will require greater elargement to et back to the same size as before you chose a new lens.  That greater enlargement will increase the size of the circle of confusion on the print.  So what you gained in decreasing the focal lngth is lost in restoing the image size.

The depth of field is doubled if the f/number is doubled.  Going from 2.8 to 5.6 doubles the depth of field.

Depth of field changes with the square of the focal distance.  Change the focal distance by a factor 2 and depth of field changed by a factor of 4.  But keep in mind the image size also changes.

Depth of field also changes inversely to the squaure of the focal length.  Ah ha,you say.  Depth of field is a function of focal length.  But the missing factor is the "negative" must be enlarged more times to produce an equal image size on the print.

When all things are  taken togeter, the focal length doesn't matter when the image size is constant.  (Don't forget that a circle of confusion is an image too.)  To get the same image size on the film or sensor, when you reduce the focal length by a factor of 2, you must move closer by a factor of 2 to get the same size image.  Or enlarge the shorter focal length image more to get the same image size.

But instead of decreasing the focal length, I can pick up my long lens and move way back.  If I increase the focus distance by a factor of 2, I will increase the depth on field by a factor of 4 because I have made the image and the circle of confusion smaller.  Same thing happens if I switc to wide angle lense and then move up to make the image bigger.
Title: The Missing Factor in Sony F828 Reviews
Post by: Howard Smith on January 28, 2004, 08:33:43 pm
I suppose the photodo experiment could have "leveled the field" by keeping the shutter speed about constant and using T-Max 100 for the 35mm and Tri-X for the 4x5.  I don't might leveling the field as long as it makes it level.

"Luminous Landscape" sot of implies the subjet and envionment we may be interested in.  Normally, cameras will be tripod mounted and shutter spedd will not be much of an issue.  Yes, I know there may exceptions, but let's think "normally."

If smaller is better, it strikes me as odd that folks much smarter than I (the Canon and Nikon pros for starters) are staying up nights trying to make bigger sensors.  What are they thinking?

Call me old fashiond (I am), but when I think 30x40 print, I think 4x5 (or bigger if I had it).  I don't think 2/3" digital or even full frame 35mm digital.  If I think small enough, then my Sony 717 is plenty good enough.
Title: The Missing Factor in Sony F828 Reviews
Post by: Howard Smith on January 29, 2004, 11:56:12 am
BJL, I would point out that except for Pentax and Fuji, I don't think any camera maker you mentioned is a player in the medium format market.  Nikon does make large format lenses, but no cameras.  So it may be not so surprising that the makers you named are working in the "35mm" market place.

I am old fashion and still prefer film to digital.  So what?  I was maybe the last person to buy a CD player.  However, I do recognize that digital is the "wave of the future," for now.  I'm not so narrow minded to think the current digital technology is the ultimate.  Someday, and maybe not too long from now, there will be a camera that will make you want to throw you digital stuff away (same way many have done with film).  Film has been with us longer than the airplane.  Within my life time, man has gone to the moon with a medium format film camera.  Digital is a baby, and a remarkable baby at that.  But just as film was not the ultimate, I doubt digital is either.  It may not have the life expectancy of film.  When man makes that next giant leap foreward and steps onto Mars, I doubt he will be armed with a 6x6 film Hassy.  And maybe not even 100 megapixal Minox.
Title: The Missing Factor in Sony F828 Reviews
Post by: Ray on January 30, 2004, 07:35:50 pm
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Even if such a sensor were perfect, the resulting images would be no better than the lens that formed it.

It does not make economical sense for one technology to progress much beyond the other.
Howard,
Can I refer you to the following quote from Norman Koren's site?

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The total detail a lens can resolve at large apertures, where performance is aberration-limited, is relatively independent of format. It is a function of lens quality and design. A good lens can resolve about the same detail at f/5.6 for 35mm as for 4x5, where the image is much larger, but 4x5 images will have more detail because 35mm images are limited by film resolution.

The crucial point here is, it's the lack of quality of film that gives the larger format its advantage. The closer you get to creating a 'perfect' film, the smaller the advantage of the larger format, at least in terms of noise and resolution. Even without any further improvement in lens design and construction, the 'perfect' film would be a worthwhile thing to strive for.

Of course, we'll never get there and we'll probably never need to get there. The questions is, how close to the 'perfect' film do we need to get, to make large format obsolete for all purposes other than creating shallow DoF?
Title: The Missing Factor in Sony F828 Reviews
Post by: Ray on February 01, 2004, 07:50:24 am
To further illustrate this point, the Olympus E-1 would be an excellent example because the Zuiko lenses appear to be so much better than the rather noisy and low resolution 5MP sensor.

DESIGN BRIEF: A sensor for the Olympus E-1 capable of delivering image quality as good or better than that from any camera in existence, including the 22MP Leaf Valeo, 8x10 field camera or 6x17cm panorama camera.

(1) Foveon type sensor consisting of 3 layers, one layer for each primary colour.

(2) Photodetector size - 4 micron, resulting in a total of 15 true megapixels with no interpolation (sensor size 18mmx13.5mm - hope my maths is correct).

(3) Each 4 micron detector divided into 16x16 sub-detectors (total 256).

(4) Each sub-detector of 0.25 micron diameter to have a different sensitivity so that each main detector will have a discrete numerical value ranging from 0-256 depending on the intensity of light passing through the microlens.

(5) Each sub-detector will be either 'on' or 'off' and the most sensitive of the sub-detectors will be switched on by the minimum number of photons that are necessary to rise above the system noise.

(6) The minimum number of photons required to switch on the most sensitive of the sub-detectors will be directly related to the camera's optimum ISO setting.

(7) Higher ISO settings will result in less than 24 bit colour, but no noise.

Okay! I've designed it. You engineers now build it!  :D .
Title: The Missing Factor in Sony F828 Reviews
Post by: Howard Smith on February 03, 2004, 09:37:54 am
Ray, even Darwin recognized that his theory of evolution was fatally flawed.  It's those that don't look deepr that continue to hang on to such notions, usually to prove one of their own view points.

You seem to think the cost of medium and large format is too high.  For whom?  You perhaps, but there does seem to a niche market out there.  In fact, I ind large format film to be not that expensive, especially for the results.  The cost of a large format lens is right in there with Canon 35mm lenses, or less.  A camera body is a few hundred dollars to a few thousand for top of the ine - much like 35mm.

Yes, I have a lot of money tied up in medium format.  But I've had the same system for almost 20 years, still works as good as ever.  I watch the turn over in 35mm and digital, and maybe a top quality medium format system isn't all that much.

Now, if you happen to be a photographer who doesn't require the latest in electronic do-everything for you but remove the lens cap and aim, even 35mm can be inexpensive.
Title: The Missing Factor in Sony F828 Reviews
Post by: BJL on February 04, 2004, 06:12:09 pm
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As I understand it, there are three broad types of noise; photon noise; dark noise and read noise. It's the additional read noise (the process of quantifying the electronic signal) which might be unavoidable if one substitutes fewer bigger pixels for a lot of smaller ones.
Ray,
   you make  an important point: perhaps you read the Roper site more thoroughly that I did!  I only considered the main sources of noise that affect the electron counts recorded in the wells of the sensor, photon noise and dark current noise, but not read noise from the subsequent analogue amplification before A/D conversion.
   Perhaps it is time to add one mathematical fact; for constant exposure time, aperture ratio, and sensor size, photon noise and dark current noise scale with the square root of photosite area, and so does discretization error in the A/D converter. Any noise source that scales with this square root behaviour is cancelled by binning or downsampling, because the S/N of combined data decreases in proportion to the square root of the number of values combined.

    But it is possible that as photosite size increases, the read noise increases more slowly than this square root pattern, and if so, increasing photosite size can give a visible benefit. In this situation, increasing site size enough would lead to read noise becoming distinctly smaller than the other sources, so noise would then be back to roughly "square root" scaling, at which point further site size increases would have no further benefit for image quality.

   So considerations of read noise (and that "well fraction" issue) will indicate a natural site size, below which noise problems get noticably worse; above which there is no significant benefit. Clearly this size limit decreases with time, as chip feature size continues to shrink and amplifiers improve, and that trend probably underlies the steady shrinkage of site size across the whole spectrum of digital sensors, with 9microns the current upper limit even in US$30,000+ digital backs.

   I speculate that Sony might have pushed a bit beyond this limit with the 2.7micron pixel pitch of its 8MP 2/3" format sensor, on the slender evicence that, according to DPReview, the 5MP downsampled output option of the Sony 828 has higher noise than the native 5MP output of the Sony 717.
Title: The Missing Factor in Sony F828 Reviews
Post by: BJL on February 07, 2004, 03:58:56 pm
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It's so easy for manufacturers to pull the blinds over the average layperson's eyes by quoting very appealing and attractive specs without reference to other very significant and limiting factors.
That is why I like working from the specifications provided by companies like Kodak and Dalsa. The other big sensor seller Sony offers only far less informative data sheets, and since Canon and Nikon are not selling sensors directly, they do not publish such data. These specifications are intended for reading by technically skilled customers, not laypersons, and so play it very straight.

   For example, the full data sheet for the KAF-5101CE sensor in the E-1 at http://www.kodak.com/global....pec.pdf (http://www.kodak.com/global/plugins/acrobat/en/digital/ccd/products/fullframe/KAF-5101CELongSpec.pdf) reports reports values like total noise [17 electrons rms] and the consequent dynamic range [67dB] that are measured at a very high maximum "guaranteed temperature of performance" of 60C, and at the maximum rated read rate of 28MHz, to give a guaranteed "worst case" value. Measuring at a more normal 20C or 25C lab. temperature would be an easy and somewhat legitimate way to improve the numbers, by reducing the thermal noise level greatly.

   By the way, from reading various Kodak documents, it seems that the total noise is "measured in the dark including amplifier and system noise", so dark current and read noise are there; everything except photon noise, which does need measurement since it is always the square root of the electron count. So it seems that no "significant and limiting factors" are being glossed over there.
Title: The Missing Factor in Sony F828 Reviews
Post by: georgj on February 09, 2004, 03:27:56 pm
Hi all,

this thread is very interesting for me, not only because I'm considering to go for a F828 but because I've heard a lot about the basic physical pirciples in digital imaging.
After reactivating my physics (long, long ago) I've made some calculations to find out, how many photons will be projected onto an sensor's photosite. These figures are important when considering the statistical error (square_root(n)) and the maximum possible dynamic range.
[for example, in bright sunlight a typical 3 µm photosite would be hit by roughly 18,000 photons given the 'sunny sixteen'-rule for ISO100 ( 1/100 exposure time, f/16)].
Is there a general rule to get the number of electrons caused by a single photon (I remember a mean efficiency of about 30%)?
Any hints are appreciated.

Georg
Title: The Missing Factor in Sony F828 Reviews
Post by: Howard Smith on February 18, 2004, 10:00:46 am
Ray, I didn't say Darwin became a Christian.    He simply realized that his theory of evolution was fatllly flawed - was not correct.  One does not have to be a Christain to beleve Darwin was wrong.  I have no idea when in Darwin's life he came to the conclusion he was wrong.  And be careful, not everything you read on the web is true.

Something on the order of 999 out of 1000 mutations are ether fatal to the organism or of no benefit.  So if the organism dies, the mutation is not passed on.  If the mutation os of no benefit, it does not assist in natural selection, and will eventually die out.

So what about the 1 in 1000?  Well, suppose an organism evolved a complete eye on its forehead.  A pretty neat trick in itself since the eye is a rather complex organ.  But unless that eye also has an optical nerve and a site in its brain to process the information and understand what it is seeing, the new eye is worthless.  The mutated eye will disappear in futre generations.  The entire optical system would have to evolve in one step.  Never happen.  It is similar to a tornado going through a junk yard and leaving a fully assembled CAnon 1Ds with a 17-40mm zoom in its path. Never happen.  Nature goes from the organized to the disorganized.  Randomness is always increasing.
Title: The Missing Factor in Sony F828 Reviews
Post by: Ray on February 19, 2004, 06:23:35 pm
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There doesn't seem to be enough time or material to make hemoglobin by chance.  You need a lot of external help.  A Designer or Creator.
Now we're really into the thick of it, aren't we! I think you're making the same mistake as in the first example. Just as a complex organ such as the eye does not mysteriously and suddenly appear as a result of a chance mutation, the complex process of haemoglobin production does not magically happen in an instant, against all odds of a million trillion to one.

Mutation and chance are ingredients in the process, but the primary mechanism in Evolution is "Survival of the fittest", which is another term which has been grossly misrepresented by the religious fraternity.

No two creatures or organisms within a species are identical. Not even two ball-bearings are identical, and the wide variation in human characteristics is patently obvious. The variation amongst ants or bacteria is less obvious. But it is this variation, when pitted against the environment by the driving force of survival, that gives some members of a species a slight advantage. They survive because they are 'more suited' to the environment they find themselves a part of, are more able to surmount the trials and tribulations of existence. Change the environment rapidly through heavy meteorite bombardment or volcanic activity, as as happened at various intervals throughout the history of the Earth, then you get mass extinctions of species that cannot adjust quickly enough to the changed conditions.

You know I'm right!  :D
Title: The Missing Factor in Sony F828 Reviews
Post by: Ray on February 20, 2004, 06:44:50 am
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For information on the moth myth, see "Icons of Evolution" by Jonathan Wells

Thanks for that, Howard. I wasn't aware there was a controversy over this classic example that appears in all introductory text books on Evolution.

Here's a critique of Jonathan Wells' book at http://www.ncseweb.org/icons/icon6moths.html (http://www.ncseweb.org/icons/icon6moths.html)

It's fascinating reading. I think you'll find the 'peppered moth' story is not entirely bunk  :D . There's certainly no evidence of fraud, although Kettlewell's methodology might have been flawed. But that's often the case with Science. There are always things we are simply not aware of. Darwin was not aware of the existence of genes and Kettlewell, who did the research on the moths, was not aware that birds can see into the ultraviolet part of the spectrum. He assumed that a moth that looked camouflaged to him would also look camouflaged to the birds.

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Atheism is quite foolish.  ..........I claim that the atheist cannot prove his position, but must take that position on faith - just like a believer in God.

So the believer in God is just as foolish as the Atheist.  :D

Actually I'm closer to being an Agnostic, but like to be a bit provocative now and again and call myself an Atheist, especially when speaking to religious people.  :)
Title: The Missing Factor in Sony F828 Reviews
Post by: Scott_H on January 23, 2004, 07:11:15 am
Maybe the issue is worse than I have had experience with on other digicams.  Either way, I don't think I would base my purchase decision on overexposed images of tinfoil.

Looking at the shots on dpr, there are some where it could be a problem.  The car and the building interior both have visible CA, but to me look like the exposure is about where it should be.

Most of the other shots are deliberatley overexposed to create CA.  Maybe some cameras wil handle that better than the 828, but to me the image is overexposed not acceptable anyway.  That would be my fault, or the fault of lighting conditions at the time I took the shot, and not the fault of the camera.

I still think people are making way too big a deal out of this.  My equipment is always going to be a big compromise.  I can't afford to spend 20K on a camera system.  I can understand the limitations of the equipment I can afford, and learn to deal with it.
Title: The Missing Factor in Sony F828 Reviews
Post by: Fabio Riccardi on January 26, 2004, 04:48:20 pm
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I would expect the performance of the Zeiss zoom to be best at around f2.8. But it would have to be significantly better than at f8 to make f8 an unusable solution to PF, especially considering the tremendous DoF advantage at f8, equivalent to almost f32 on a 35mm camera.
In my tests with my F828 (shooting a PIMA/ISO 12233 target) the lens appears to be sharpest around f/5.6.

There is no significant sharpness degradation at f/8.

DOF is significantly deeper than my 10D, although you can get nice OOF backgrounds when shooting at the long end of the zoom.

BTW: IMHO the F828's lens has really excellent bokeh compared to other digicams I've seen.

 - Fabio
Title: The Missing Factor in Sony F828 Reviews
Post by: Ray on January 27, 2004, 12:36:34 am
Howard,
The maths seems to say you are essentially right. The bigger F stop number of the larger format produces a larger CoC. The smaller F stop number of the smaller format (for equivalent DoF and focal length) produces a proportionally smaller CoC.

However, the smaller format has to be enlarged more to produce equal sized prints to the same degree that the CoC is smaller.

Result: back to square one. I can only conclude that the smaller format has no ultimate DoF advantage, but the bigger format does, in terms of a potential shallower DoF if required.

But there is another factor, isn't there! Michael's test shots comparing the F828 and 10D were all taken at f5.6, including the Canon L zooms, and resolution was considered to be on a par. I would be very surprised if those Canon zooms showed equal sharpness at F5.6 and f13.

Can we therefore conclude that the F828 has the potential to deliver higher resolution than the 10D with regard to those areas that are exactly in focus, even though the areas that are out of focus might have the same size CoC's after enlargement to equal size prints?
Title: The Missing Factor in Sony F828 Reviews
Post by: Ray on January 28, 2004, 07:18:18 pm
If they are not the same in terms of noise. If one camera or the other has more objectionable noise, at equal shutter speeds and equivalent DoF, (although similar resolution) then at least we shall know which camera has the advantage in the nightclub situation and can avoid much fruitless debate.  :D
Title: The Missing Factor in Sony F828 Reviews
Post by: Ray on January 29, 2004, 07:32:21 pm
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Digital is a baby, and a remarkable baby at that.  But just as film was not the ultimate, I doubt digital is either.  
We should not forget that digital cameras, like modern hi fi sets attached to CD and DVD players, are a mixture of digital and analogue processes. In fact, the most significant part of a digital camera, the digital sensor, is still in large part analogue. (If I've understood the process correctly  :D )

We have a photosite or photodetector which accumulates an electrical charge in proportion to the number of photons that have impinged upon it. That's analogue.

As with all analog signals, the accuracy of the match between the signal and what it represents, is degraded by real world interference - in short, noise from whatever source, including noise introduced in the process of converting those millions of different electrical charges to digits.

Now I know you're not so old-fashioned that you don't appreciate the significance of a true digital process  . If that picture information could be digitised at the precise moment the photons impinge upon the photodetector, we'd have a true (and perhaps the ultimate) digital camera.

How this could be possible in practical terms, I don't know, but it's not difficult to imagine a small sensor, say 2/3rds", with literally billions of photosites. Instead of accummulating varying degrees of electrical charge subject to severe degradation, each photosite would be in a state of 'on' or 'off' depending on whether or not it had received a specified minimum number of photons, say 6 being the minimum quantity to rise above the noise floor.

Such a system would probably be comprised of 3 sensors, one for each primary colour. The resulting image would consist of nothing but the presence or absence of 3 dots, red, blue and green, which is all you need - a bit like your computer monitor really.

Of course, it goes without saying that current computers couldn't handle all that information. We'll probably have to wait until quantum computers become a reality. Even at the present time, if Canon were to manufacture a full frame 35mm sensor with the same pixel density as the F828 (which I think would be feasible), it would be aprox. a 130MP sensor producing 390MB images in 8 bit and 780MB images in 16 bit.
Title: The Missing Factor in Sony F828 Reviews
Post by: Howard Smith on January 31, 2004, 10:30:45 am
The resolution of an image is found mathematically by:

1/(image resolution) = 1/(lens resolution) + 1/(film resolution)

So you can see that as film resoltion becomes infinte, the image resolution becomes the lens resolution.  Same foe a perfect lens.

This makes sense if you assume a perfect lens.  The image cannot be "sharper" the the film it is on.  Likewise, an image on perfect filmcannot be sharper than the lens can project.
Title: The Missing Factor in Sony F828 Reviews
Post by: Ray on January 31, 2004, 07:23:30 pm
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The resolution of an image is found mathematically by:

1/(image resolution) = 1/(lens resolution) + 1/(film resolution)

So you can see that as film resoltion becomes infinte, the image resolution becomes the lens resolution.  Same foe a perfect lens.

This makes sense if you assume a perfect lens.  The image cannot be "sharper" the the film it is on.  Likewise, an image on perfect filmcannot be sharper than the lens can project.
Howard,
With all due respect, you appear to have missed my point  :) . All the above you've written is true. However, the point I am making is this: The current resolution advantage that large format film cameras have (and have always had)over small format film cameras is NOT necessarily due to the superior resolving capability of the LF lens, but due to the 'effective' superior resolving capability of the larger piece of film.

But you clearly know this already because it was you who first referred recently to that fairly old Photodo experiment comparing a high quality 35mm lens at f5.6 with LF 9x12cm format at equivalent DoF aperture setting of f22.

The fact that, even with very imperfect film and current lenses, it is possible under certain circumstance to achieve 35mm resolution that equals 4x5, should be a strong clue that it's only a matter of time before sensor development reaches that level of noise-free quality that makes MF and LF obsolete.

I was initially disappointed in the first test results of the Olympus E-1, and that was due to the limitations of the 5MP sensor. However, I can now see that further sensor development could result in those Zuiko lenses outperforming anything the Canon 1Ds can currently deliver.
Title: The Missing Factor in Sony F828 Reviews
Post by: BJL on February 03, 2004, 12:58:47 pm
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On the issue of larger numbers of smaller pixels being able to do as well as smaller numbers of larger pixels, I think we're really fudging the results a bit, don't you? It's a game in which dynamic range is always going to be limted and the additional noise is always going to be there.
No, it is not fudging in the slightest; if photosite size reduction is not too extreme, visible noise levels will NOT be increased and dynamic range will NOT be decreased, as measured on prints of the same size.  This is the clear if surprising  consequence of the mathematics of randomness and noise, which is in my professional area, so I could give a rather detailed scientific and mathematical explanation; but let me try to wave my hands instead. (The 828 MIGHT have gone a bit too far in site size reduction though.)


Claim

If you makes two sensors using the same basic technology and of the same size, but with different photosite sizes, staying within the size limits for which the electron wells can occupy roughly the same fraction of the total sensor surface and so have give the same maximum electron capacity per unit area, then you will have roughly the same effective dynamic range, fineness of tonal gradations etc., when comparing on the basis of prints of the same size, or through files resampled to the same pixel count.  The worse S/N ratio and dynamic range of more numerous smaller individual pixels is exactly balanced by the greater number of them used to print each given portion of the final image.


Handwaving illustration, for the case of quadrupling the pixel count and then "binning" or downsampling

Combining the signals from a 2x2 collection of smaller sites (say 4microns) into one output pixel will give you the same total signal and total noise as if one had used one bigger photosite (say 8 microns) directly to produce that output pixel; the signal and noise values are just divided into several smaller pieces and then recombined later, instead of being combined on the sensor to start with.

   Since signal values are always positive or zero, but noise values are a mixture of positive and negative, combining the latter causes some cancellation, so the combined noise level grows less than the combined signal level, which is how binning or downsampling gives better S/N ratio than that of the values combined. (the Roper Scientific web site has some discussion of binning.)

   Printing is analogous to binning: prints of the same size might be produced at say 200PPI (8p/mm) from the sensor with fewer, bigger sites or 400PPM (16p/mm) from one with four times the pixel count, and so each small patch of paper (1/200inch square) that gets its input from one pixel in the first case blends together input from 4 pixels in the second case.
Title: The Missing Factor in Sony F828 Reviews
Post by: Ray on February 04, 2004, 09:07:38 am
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Quote
Ray, even Darwin recognized that his theory of evolution was fatally flawed.

Flawed, maybe. Fatally, never!  :D

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You seem to think the cost of medium and large format is too high.  For whom?  You perhaps, but there does seem to a niche market out there.

Actually, I own a couple of second hand MF cameras, a Mamiya RB67 and a Fuji GSW690lll. I would never have paid the new price for these, but I'm a sucker for a bargain.

The fact is, even though I got these at a good price, I can hardly describe them as a bargain because I now rarely use them. They might eventually become collectors items. Since getting the Canon D60 a couple of years ago, I've taken more photos than in my entire life previously, many, many more. The whole process of buying film, getting it developed then scanning it is too much trouble (and expense). I'm now totally 'spoiled' by the convenience of digital.  :D

It's a great feeling to know I can press that shutter as often as I like without it (necessarily) costing a cent. You should try it some time.  :D
Title: The Missing Factor in Sony F828 Reviews
Post by: Ray on February 06, 2004, 10:54:54 pm
BJL,
We really need to be educated on the significance of these specifications. It's so easy for manufacturers to pull the blinds over the average layperson's eyes by quoting very appealing and attractive specs without reference to other very significant and limiting factors.
Title: The Missing Factor in Sony F828 Reviews
Post by: georgj on February 09, 2004, 03:41:01 pm
something I forgot... 18,000 photons resulting from a bright (isotrope) reflecting white surface.

Georg
Title: The Missing Factor in Sony F828 Reviews
Post by: Ray on February 18, 2004, 01:32:46 am
Quote
Ray, even Darwin recognized that his theory of evolution was fatally flawed.  It's those that don't look deepr that continue to hang on to such notions, usually to prove one of their own view points.
Howard,
Sorry to drag this up again, but I just had a visit from the local pastor, and during the conversation he mentioned that Charles Darwin had admitted he was wrong, on his death bed, and experienced a conversion to Christianity before he died.

This is total misinformation perpertrated by the religious community. No such event happened, and Darwin died an Aetheist or an Agnostic. (Check the internet.)

Nothing much to do with photography, but I thought I'd mention it, just to keep the record straight.
Title: The Missing Factor in Sony F828 Reviews
Post by: Howard Smith on February 19, 2004, 05:45:50 pm
Ray, you mentioned that the Pope is not an "evolution denier."  I am surprised you would add him as an expert.  Most Christians do not hold the Pope to be infallible.  In fact, it was the Pope that had Bruno burned at the stake for claiming our solar system was only one of many similar systems.  He also threatened to torture and kill Galileo if he did not renounce Capernicus and the notion the earth is not the center of the universe, but moves about the sun.  Galileo gave in and was sentenced to prison for the rest of his life.  Being Pope doesn't necessarily make you correct.
Title: The Missing Factor in Sony F828 Reviews
Post by: A Scottish soul on February 20, 2004, 08:07:05 am
Ray

I too claim to be an agnostic as I personaly doubt large swathes of the Bible and wonder which of all the main world religions is the right one, if any! They can't all be right so are probably all wrong IMHO.

However this has nothing to do with my next question.

One of youre posts in this thread suggested an alternative method of sensor design. 4/3ds size, Foveon style in 3 layers with 256 individual micro photo sites per sensor of 4u size. Here is one possible alternative that would be possible if the technology exists for you're suggestion.!

Instead of using the 256 micro sensors, which are still analog by design, just use one and use it to count photon strikes via a digital counter capable of counting up to the 15000/3 layer = 5000 photons expected for a bright day or more to add extra dynamic range. This would be a 13 bit counter giving 8192 levels ov brightness.  Then you would have a 100% digital system with unlimited dynamic range, depending on the max value possible in the counter. The digital value in the counter would then be read out after the exposure. Speed of operation of the counter would be key to its possibility and also squeezing the small detector and counter registers into a 4u square area. This is unlikely at the pressent but who knows what the nano technologists may be able to do on silicon in the not to distant future!


What do you think about this one?


John