Luminous Landscape Forum
Equipment & Techniques => Medium Format / Film / Digital Backs – and Large Sensor Photography => Topic started by: BJL on October 25, 2006, 03:35:37 pm
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Why do the new generation of medium format lenses rarely go beyond f/2.8, and not beyond about f/3.5 at typical portrait focal lengths? In the past there were lenses as "bright" as f/1.8 (manual focus) from Mamiya and one f/2 AF lens for Contax 645.
Even allowing for the longer focal lengths usable to get the same FOV in a larger format, f/2.8 in 645 format gives shallowest DOF comparable to only about f/1.6-1.8 in 35mm format, and with 36x48mm format sensors the limit is like f/1.8-2.1, yet I read many people insisting on the importance of lower f-stops than that for 35mm format, down to at least f/1.4 and preferably f/1.2.
Are extremes of shallow DOF of less interest in MF than smaller formats like 35mm?
Is the importance of extremely shallow DOF in 35mm (and smaller) formats exaggerated?
Are recent medium formats systems failing to deliver what customers need when it comes to shallow DOF for portraits?
Is there some other explanation for the more limited "selective focus" capabilities of the current AF MF systems?
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I would personally like to see faster MF lenses - f2 would be great (for available light shooting as much as short DOF) and fortunately there are a few available. f2.8 is quite decent too. There are probably more fast lenses than you think. Here is a list I made which is probably missing one or two.
Rollei PQ/S: 50mm f2.8, 80mm f2, 80mm f2.8, 110 f2, 180mm f2.8
Contax 645: 80mm f2, 45mm f2.8, 140mm f2.8
Bronica ETR (645) has a 50mm f2.8, 60mm f2.8, 75mm f2.8.
Bronica SQ series (6x6): 80mm f2.8
Hasselblad V: f/2.8 80 mm 'C' lens. The rest of the C series is slower. The F lenses were faster: f/2 110 mm, f/2.8 50 mm, f/2.8 80 mm and f/2.8 150 mm
Hasselblad H: HC f/2.8 80 mm and HC f/2.2 100 mm
Mamiya 645: 80mm f1.9, 80mm f2.8, 45mm f/2.8, 55mm f/2.8, 150mm f2.8, 200mm f2.8, 300mm f2.8
Mamiya 67: 110mm f2.8
Pentax 67: 75 mm f2.8, 90mm f2.8, 105 mm f2.4, 165mm f2.8
Pentax 645: 45mm f2.8, 75mm f2.8, 150mm f2.8
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One thing I have noticed as an advantage to the larger formats when it comes to depth of field is the issue of separation of the subject from the background.
This is not about the calculated amount of depth of field or the amount of background blur involved. Rather, it has to do with the amount of detail available at the plane of sharp focus vs. the defocused areas. The idea behind this is that once an area is defocused, added resolution from a larger film format doesn't really matter, except perhaps in smooth tonalities. However, at the plane of sharp focus, the added resolution from larger formats does make a difference.
For example - I have a Canon 35mm f/1.4 L that I use on an EOS 3 and I also have a Rodenstock 150mm APO Sironar S f/5.6 that I use on 4x5. If you crop the 35mm shot to a 4x5 aspect ratio, the 35mm and 150mm lenses have very similar fields of view. Also, when shot wide open they have roughly the same calculated depth of field and background blur. Why then does the larger format give a greater percieved separation of the subject from the background?
Here's my hypothesis. Let's say both lenses are capable of resolving 40 lp/mm at the plane of focus when shot wide open (a pretty conservative assumption). If you need a final print resolution of 6 lp/mm, then you can make a ~7x enlargement from the original film and still retain critical sharpness. This means at print sizes under 8x10, then the plane of sharpness for both 35mm and 4x5 will be roughly similar (though I notice a difference between 4x5 and 35mm at 8x10 size). Once you enlarge to 8x10 or larger, then the 4x5 shot has a detail advantage at the plane of focus, not really hitting the limit until over a 30 inch print. If you take 35mm up to these larger sizes, the plane of focus just doesn't hold up.
Therefore, for any print larger than 8x10, the larger film size produces greater resolution at the plane of focus, while the defocused areas remain blurred regardless of format. This creates an increase in the perceived separation between the sharpness of the subject and the blurred background.
The larger print sizes also change the circle of confusion to a more stringent value and create an effectively shallower depth of field. So, while the depth of field calculations for a smaller prints may show the advantage going to 35mm for shallow depth of field with its f/1.0 and f/1.2 lenses, the larger formats actually contain much greater potential for shallow depth of field when you go to larger print sizes.
I think I'm on track with this line of thinking, but input is welcome.
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BJL, you're absolutely right that depth of field tables only give a partial explanation of the full realities of focusing. You'll get some useful insights into your question here,
http://www.bobatkins.com/photography/technical/mtf/mtf6.html (http://www.bobatkins.com/photography/technical/mtf/mtf6.html)
And I'd also recommend visiting Harold Merklinger's website and buying his pamphlet on the subject.
Bob Atkins illustrates that two different lenses with the same calculated depth of field can have very different visual characteristics. Harold Merklinger takes the issue further and argues that for some subjects a radically different approach to focusing can yield significantly better results.
Other authorities have made additional attacks on the orthodoxy of depth of field tables, for example Kornelius Fleischer, Zeiss's marketing manager, has pointed out that depth of field tables only apply to the very centre of the image, off axis there are different rules that apply. And even more startling is his assertion that depth of field tables are merely theoretical approximations and different lenses of the same focal length can have different depth of field characteristics. He says for example that the Hasselblad 250mm superachromat has a shallower working depth of field at the same aperture than the regular Hasselblad 250mm lens. I also suspect that many other modern and complex lenses actually have less effective depth of field than some of their older, simpler counterparts.
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As lenses get better, and particularly if metamaterials with a negative refractive index currently being produced in the lab with nanotechnology, ever become a practicable option for construction of camera lenses, then standard DoF calculators should actually be more correct, with an appropriate adjustment of CoC, since current DoF tables address degrees of OoF (out-of-focusness) at various distances from a point of perfect focus with an ideal, perfect lens.
If the CoC is chosen in relation to what the eye can see (your eye for example) on a given size print from a specified distance, it makes no difference to the perception of DoF on the print if the lens is capable of resolving detail smaller than the chosen CoC. In such a case, that additional resolution of the lens is wasted (on the smaller than need be print) and the DoF caculations should still hold.
As lenses and sensors become higher resolving, the perception of DoF should only change on appropriately larger prints, which will appear to have a shallower DoF because what's in focus will be sharper, but what's out-of-focus should be similarly fuzzy.
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... and particularly if metamaterials with a negative refractive index currently being produced in the lab with nanotechnology
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Negative refractive index???!
How does (speed of light in a vacuum)/(speed of light in the material) ever become negative? Or even become less than unity?
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More simply put..
A larger chip has less depth of field for a given angle of view and aperture
For some this is an advantage for others it is not
This scenario is know as the MF look - loved by many - hence the desire for larger chips than more MP
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It is (exponentially) difficult,expensive and heavy to construct very wide aperture lenses with suitable image circle to cover a 645 chip
Given the minimal DOF rendered by current lenses wide open some would consider them pointles anyway
Others would relish the bright view rendered through the viewfinder even when not shooting at that aperture
Read again..
A larger chip has less depth of field for a given angle of view and aperture
SMM
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Negative refractive index???!
How does (speed of light in a vacuum)/(speed of light in the material) ever become negative? Or even become less than unity?
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Don't ask me. I'm not a physicist. Just repeating what I've read . Apparently there's work going on to produce transparent artificial materials with different properties to glass, which enable the laws of diffraction to be extended so that a lens at say f64 will have the resolution of a lens at say f8.
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Other authorities have made additional attacks on the orthodoxy of depth of field tables, for example Kornelius Fleischer, Zeiss's marketing manager, has pointed out that depth of field tables only apply to the very centre of the image, off axis there are different rules that apply. And even more startling is his assertion that depth of field tables are merely theoretical approximations and different lenses of the same focal length can have different depth of field characteristics. He says for example that the Hasselblad 250mm superachromat has a shallower working depth of field at the same aperture than the regular Hasselblad 250mm lens. I also suspect that many other modern and complex lenses actually have less effective depth of field than some of their older, simpler counterparts.
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Gary,
I recently picked up a Canon 50/1.4 at a good price in Bangkok. I'd been meaning to buy one for some time due to the embarrassment that my sharpest lens was by far the cheapest, the 50/1.8 ll. But the fact is, although many photographers seem to drool over the ultra wide apertures of such lenses, including the f1.2 of the 85/1.2, such lenses have pretty lousy performance at full aperture, including the very expensive 85/1.2.
Checking the Phodo MTF charts for these lenses, the 50/1.4 at f8 is quite outstanding with an MTF response of around 70% at 40 lp/mm all the way to the edges (18mm). However, at f1.4, even in the centre, MTF is only 35%, falling to around 15% at the edges. The 85/1.2 is hardly better with an MTF of arounf 38% at the centre, falling to around 20% at the edges.
These are very poor performance figures for any lens, so I decided to take a few test shots from my hotel room balcony using my new 50/1.4 at all apertures. With lens focussed at infinity at f1.4, a tiled roof in the foreground (about 25m away)appeared to be noticeably OoF. However, at f1.4 the performance of the lens is so bad (worse than at f22), it's difficult to tell if the roof is more out-of-focus than the rest of the image, so one would have to conclude that DoF is just fine, as it is with a pin-hole camera.
The attached 100% crops below tell the story.
[attachment=1115:attachment] [attachment=1116:attachment]
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A larger chip has less depth of field for a given angle of view and aperture
For some this is an advantage for others it is not
Absolutely agreed.
This scenario is know as the MF look - loved by many - hence the desire for larger chips than more MP
It is (exponentially) difficult,expensive and heavy to construct very wide aperture lenses with suitable image circle to cover a 645 chip
I think that the idea that the MF look is exclusively because of shallow depth of field is the reason BJL asked his question.
The question stems from the fact that in MF there are no equivalents to lenses such as the 35mm f/1.4, 50mm f/1.2 or 85mm f/1.2 that are available to 35mm shooters. Running calculations or using a depth of field calculator shows that there is actually less depth of field with a 50mm f/1.2 lens shot wide open on 35mm than there is with a 80mm f/2 lens shot wide open on 645. The same is true if you compare the 85mm f/1.2 L with the 110mm f/2.
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My thinking is that this is not the whole story. Using a larger imaging chip or film format does a couple things. It places less lp/mm demand on the MF lens for any given print size, likely gets the lens to a range where the MTF is better because of those lower demands, and allows for greater resolution at the plane of focus.
I believe that when these things are combined, you get greater perceived separation from the subject to background (contrast of sharp vs blur) when at smaller and medium print sizes, and also gain the ability to print larger with the larger format, which will actually result in ultimately shallower depth of field when the small format hits the limits of enlargement.
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My thinking is that even if 35mm can produce shallower depth of field when using the fastest lenses, MF holds the upper hand due to:
1) Better separation from subject to background (sharp vs. blur).
2) The POTENTIAL for shallower depth of field, when print sizes larger than the limits of 35mm are used.
Of course these aren't the only advantages of MF over 35mm, but I think they are pretty important in terms of the perception of depth of field.
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My thinking is that this is not the whole story
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Now I dont read charts - I leave that to captains of ships
But I think it is the whole story.
My proof of this is if you stick a 645 lens on a 35mm body you get the same image - just less of it
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I read glossy fashion mags A4 size all the time and the amount of MF/LF work is obvious even at that size due to the lack of DOF
At smaller apertures the less DOF of MF becomes more apparent because the background is still more fuzzy - many want that blown background but still a reasonable DOF
I was shooting food today and scratching my head on whether to control my DOF through a wide aperture or a longer lense - I have not made up my mind
A thought is that Items; people food whatever look most natural when viewed from a distance that one is used to viewing them from, once you have decided the crop you want a lense lengtth is therefore defined and aperture selected on required DOF
SMM
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Why do the new generation of medium format lenses rarely go beyond f/2.8, and not beyond about f/3.5 at typical portrait focal lengths?
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I think the answer is still size - which equals cost and weight.
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Many medium format cameras have built in leaf shutters which limits the maxiumum aperture of the lens. That is why there is an 80mm f2.8 but only a 150 f4.]
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Now I dont read charts - I leave that to captains of ships
But I think it is the whole story.
I read glossy fashion mags A4 size all the time and the amount of MF/LF work is obvious even at that size due to the lack of DOF
At smaller apertures the less DOF of MF becomes more apparent because the background is still more fuzzy - many want that blown background but still a reasonable DOF
SMM
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My apologies, Sam, you are right.
I was thinking just in terms of depth of field at the plane of focus, and totally overlooked the degree to which the backgound is blurred in larger formats.
Yes, if you use an 80mm f/2 on 645 and a 50mm f/1.2 on 35mm the "depth of field" wide open is very similar at the plane of focus, and the field of view is similar as well, but the 80mm on 645 does blur the background to a greater degree.
I was wrongheaded in thinking that depth of field is the same as the degree of background blur. All it took was a few minutes of playing with my 35mm, 6x6, and 4x5 cameras and a normal lens on each to see the light.
Thanks for your patience with me.
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Many medium format cameras have built in leaf shutters which limits the maxiumum aperture of the lens. That is why there is an 80mm f2.8 but only a 150 f4.]
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All the Rollei lenses I listed above are leaf shutters, and they can still manage f2
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My apologies, Sam, you are right.
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Rare words on these forums - appeciated
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The background of the 645/80/2 looks like the background not of the 35/50/1.4 but the same as as the background of a 35/80/2
strange but true
more telephoto like cut in the plane of focus
I think how you define muzzyness is subjective - I subjectively believe 645 to look nicer not nessacarily more muzzy - just nicer muzzines - in fact I am still confused as to which is more muzzy
SMM
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The background of the 645/80/2 looks like the background not of the 35/50/1.4 but the same as as the background of a 35/80/2
strange but true
Yes that's true that a 35mm image is effectively a crop of a 645 image with the same lens. But when you compare similar images taken with 35mm and 645, the 645 lens will of course have to be of a longer focal length and will therefore have a more pronounced DOF at the same aperture.
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With all due respect, I think many replies hear repeat some of the most common misconseptions about DOF.
Our very own Michael has written a brief article (http://www.luminous-landscape.com/tutorials/understanding-series/dof.shtml) about it , and here (http://en.wikipedia.org/wiki/Depth_of_field) a more elaborate explanation is offered.
While it's true that not all lenses are created equal, it helps to keep in mind that basically aperture and magnification are the only values which determine DOF.
That explains how a larger format can change DOF, and the focal length lens can't; how a 35mm , 6x6 and 4x5 camera produce identical DOF once you match the focal length and apertures used.
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While it's true that not all lenses are created equal, it helps to keep in mind that basically aperture and magnification are the only values which determine DOF.
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I would add the focus distance - distance from camera to point of focus - and the lens' focal length.
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hi Depth of field of a 150mm 35mm lens is the same as the dof of a 150mm lens for 4x5 at the same fstop. Thats why a 240mm lens on a 8x10 gives this amazing effect of very little dof but an extreme wide angle look. You cannot get this with any other 'smaller' format. Look at the work of Jock Sturgess. As far as I know he only uses one lens, the 240 on his 8x10.
Thanks Ivan
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Many medium format cameras have built in leaf shutters which limits the maxiumum aperture of the lens. That is why there is an 80mm f2.8 but only a 150 f4.]
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Is there some reason a leaf shutter could not be made larger if needed to make a faster MF lens? Maybe lens size is limiting shutter size instead of the othr way around. No use making a really big shutter for the same "small" lenses.
Just curious.
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Is there some reason a leaf shutter could not be made larger if needed to make a faster MF lens? .
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A copal 3 shutter is big and has a max speed of 125
Copal 0/1 are smaller and go up to 500 I think
One would assume that the physics of 'hurling the gate shut' gets harder as size increases - not impossible just more costly
I think copal know a thing or two about shutters - if it was easy theyd do it
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I used to have a nikkor 80.14 was Massive compared to the 80 1.8 - when it got nicked I replaced it with the lense that went in my pocket - the 1.8
Its all about percived market demand by the manufacturers for silly glass - manufacturers already sharing a small slice of cake?
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A copal 3 shutter is big and has a max speed of 125
Copal 0/1 are smaller and go up to 500 I think
One would assume that the physics of 'hurling the gate shut' gets harder as size increases - not impossible just more costly
I think copal know a thing or two about shutters - if it was easy theyd do it
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Sounds like an interesting challenge that could be solved for a price. But what price for the few they might sell? A Hasselblad 80/2.8 goes for $2150 at B and H these days. An 80/1.4 would be fairly low demand and very high priced (comparitvely), making demand even lower and price yet higher.
I would think that a fast MF lens would require a fast shutter to use the increased lens speed. Sounds to me like an economics problem not worth solving.
I agree Copal knows shutters. I think if it were economical (not necessarily easy) Copal could solve the problem. Like going to the moon. It can be done, but at what price and is it really worth it?
Thanks for the answer.
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Thanks for many interesting responses. Two related ideas particularly appeal. Firstly:
2) The POTENTIAL for shallower depth of field, when print sizes larger than the limits of 35mm are used.
[a href=\"index.php?act=findpost&pid=82386\"][{POST_SNAPBACK}][/a]
and relatedly, the idea that perceived DOF is related to the difference in sharpness between completely in-focus elements of the image and other parts: increasing the sharpness of the main in-focus elements increases the perception of other parts being OOF, especially if the greater sharpness invites closer viewing of the print.
In other words, the use of medium format rather than a smaller format can lead to some combination of larger prints, closer print viewing, or more careful print scrutiny, all making OOF effects more noticeable and so decreasing what I will call "perceived DOF".
Indeed, medium format is typically used for the sake of higher resolution, larger prints and prints that receive more careful viewing, so standard DOF calculations based on equal sized prints might be misleading. And standard DOF charts and CoC values are based on viewing rather small 5"x7" prints!.
So for larger, higher resolution formats, another approach to DOF comparisons could be this:
compare prints of equal l/mm resolution on the print, which in digital terms means roughly equal PPI printing, and then equal viewing distance since the equal print resolution allows that.
In that viewing comparison, the DOF formulas should be used with a CoC value related to pixel pitch, not directly to format. Current 35mm and MF digital offerings offer similar pixel pitches and so can perhaps be compared roughly with the same CoC, and the same is roughly true with film. If so, DOF scales rough proportional to aperture ratio and inversely with square of focal length.
So for example, 80mm f/2.8 in MF matches about 50mm f/1.1 in 35mm. Or to compare 24x36mm to 36x48mm digital, the focal length factor is about 1.4, so the equivalent f-stop for equal DOF changes by a factor of two: f/2.8 in Hassleblad-Imacon/Fujifilm's "48mm format" matches f/1.4 in 35mm format, and the brightest current AF MF lens, the Fujinon HC 110mm f/2.2 for the H system, matches f/1.1 in 35mm format.
That f/1.4 to f/1.1 equivalent DOF is probably shallow enough for most purposes.
P. S. As to the disappearance of those even larger f/2 and f/1.9 apertures, leaving only one current AF MF lens faster than f/2.8: the motivation for that extra aperture size might have been mostly more shutter speed rather than less DOF, and that is somewhat less of an issue with the higher ISO speeds of digital, even MF digital sensors with their lesser emphasis on high ISO speeds.
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BJL, DoF is perceived - it is the OoF areas that are perceived as acceptable in focus. No need for changing the definition. Diferent people will perceive the same print differently.
I think the standard way of determining DoF still works just fine for larger, higher resolution camers. Just scrap the "standard" that says all prints are small and viewed form a certain distance. Using the same methods, DoF can be determined for large prints viewed at close range. It requires a smaler CoC, not some "standard" value.
Smaller CoC at the sensor allows both greater enlargment and closer viewing. That also makes DoF non-format dependant - which it always has been.
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Indeed, medium format is typically used for the sake of higher resolution
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Not any more buddy
It is used for shallow DOF that pings the subject off the page
and because canon WA a are a bit dodgy
I wager that 80% of commercial MF shooters rarely have a client that needs more than 16mp
This argument is rather bakced up by the fact that a P25 with a bigger sensor still outprices the higer res smaller sensor options
SMM
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Not any more buddy
It is used for shallow DOF that pings the subject off the page
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Perhaps you should reread my original post: by standard DOF reckoning (comparing equal sized prints from the same distance), medium format lenses cannot give DOF as low as one can get from fast 35mm format lenses, due to fact that MF lenses have significantly higher minimum f-stops.
Are you stuck in the endless fallacy of assuming that equal f-stops always are (or even always can be) used with different formats and different focal lengths, ignoring the fact that minimum f-stops available actually tend to increase with focal length (beyond normal) and with format for which the lens is designed?
As to current MF back resolutions, the minimum I know of is 17MP, not less than anything in smaller formats, most are at least 22MP, and the new wave is 30MP to 40MP, well beyond 35mm format pixel counts.
Of course there are other reasons for some to get a MD digital back even if it were to only match 35mm digital for pixel count: backward compatibility with a good and expensive collection of lenses, and access to some MF lenses for which there is no match is any smaller format system from Canon, Nikon etc. But the weakness of the Canon alternatives in particular is not that they do not offer extremes of low DOF. More likely the weakness is in resolution, which is part of my point.
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BJL, DoF is perceived ... No need for changing the definition. ... Diferent people will perceive the same print differently.
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I know that DOF is perceived: that is why I used the phrase "perceived DOF" to emphasize that one must take account of differences in viewing conditions and even in how careful the image gets scrutinized.
The only definition I am putting aside is the standard one underlying standard DOF tables and DOF marking on lenses, which is based in part on the assumption of a particular print size (about 5"x7") and a particualr viewing distance (about 10"?) and a particular degree of visual acuity in the viewer. This is the definition that you also reject, since by using CoC values in proportion to format size, it suggests that DOF depends directly on format!
Finally, nothing I am saying is related to differences between different viewers: I am interested in how changing the camera, lens choices, focal lengths etc. effects the DOF that is perceived by the same viewer.
To paraphrase something you have often said, it is best compare by varying only one factor (or as few as possible) while holding others constant, so when comparing cameras and lens systems of different formats, hold the viewer constant, so as to eliminate effects of differences in visual acuity or tolerance for image fuzziness.
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Perhaps you should reread my original post: by standard DOF reckoning (comparing equal sized prints from the same distance), medium format lenses cannot give DOF as low as one can get from fast 35mm format lenses, due to fact that MF lenses have higher minimum f-stops.
Are you stuck in the endless fallacy of assuming that equal f-stops always are (or even always can be) used with different formats and different focal lengths, ignoring the fact that minimum f-stops available actually tend to increase with focal length (beyond normal) and with format for which the lens is designed?
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Just because a print design may require a focal length lens or f/stop that I do not have or is not available, does not make the design invalid or wrong. I just can't achieved it. No reason to throw out science or methods because a design calls for a 200mm f/1.4 and I don't have a 200mm f/1.4 or it doesn't exist for my camera.
I need another image, not new methods. I just can't take the photo I had in mind. Methods don't care what I have in my camera bag.
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I know that DOF is perceived: that is why I used the phrase "perceived DOF" to emphasize that one must take account of differences in viewing conditions and even in how careful the image gets scrutinized.
The only definition I am putting aside is the standard one underlying standard DOF tables and DOF marking on lenses, which is based in part on the assumption of a particular print size (about 5"x7") and a particualr viewing distance (about 10"?) and a particular degree of visual acuity in the viewer. This is the definition that you also reject, since by using CoC values in proportion to format size, it suggests that DOF depends directly on format!
Finally, nothing I am saying is related to differences between different viewers: I am interested in how changing the camera, lens choices, focal lengths etc. effects the DOF that is perceived by the same viewer.
To paraphrase something you have often said, it is best compare by varying only one factor (or as few as possible) while holding others constant, so when comparing cameras and lens systems of different formats, hold the viewer constant, so as to eliminate effects of differences in visual acuity or tolerance for image fuzziness.
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So we agree?
How about when comparing camera systems of different formats, also holding the lens focal length and f/stop constant (unchanged) when looking for the effect of format changes?
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How about when comparing camera systems of different formats, also holding the lens focal length and f/stop constant (unchanged) ...
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Howard,
that is one comparison that can be done of course, and you have done it many times. But as you know well, it involves changing the FOV of the full image recorded by the camera, and that is a rather uncommon situation. Most of us are far more interested in what happens when we hold the (uncropped) FOV constant.
It is just a matter of which quantities ones wants to hold constant, which depends on the photographic purpose for which the comparison is being done. My purpose is usually to record a given FOV using as much as possible of the available film or sensor area, so I usually increase focal length when I use a larger format.
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But the weakness of the Canon alternatives in particular is not that they do not offer extremes of low DOF. More likely the weakness is in resolution,[a href=\"index.php?act=findpost&pid=82547\"][{POST_SNAPBACK}][/a]
I disagree with this - it is fine to disagree - each chooses a system suitable to thier needs
My hypothesis on the popularity of the Mf look is that for example with fashion a really wide aperture is not suitable becuase say for a half length the clothes and the models face cannot both be sharp with a lense like an 80 (mf645)
A small enough aperture must be selected to produce acceptable sharpness over this required range - eyes to logo on breast in this case
The desire MAY then to be have the bacground OOF - a larger chip will make this occur and is then for some highly desirable
My observation (that may be totally wrong) of glossy fashion and food is that very wide apertures are rarely used but the look (of the background) is created by the large format of the recording device - often still 67 or 54
ROll on a 16mp 67 chip - I would choose it over a P30 - others wouldnt
I am still struggling with why I cant the right result with the razor focus with say my 300 2.8 (35mm) - basically the focus is a nearer to infinity so doesnt drop away and the background pulled in which creates an unnatural perspective even with the right DOF
I own a 50 1.2 and know that (close in) the DOF is actually a bit useless exept for creating what some what call a bit of a joke effect I rarelly shoot it open although I love the birghtnes of view
My 50 1.2 cant do what my 80/2.8 blad can do - give a sharpish subject with a natural relationship with its background - both in terms of size or OOFness
For my magazine work my SLRN has very adequate resolution but just looks wrong or not as right as my blad
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A small enough aperture must be selected to produce acceptable sharpness over this required range - eyes to logo on breast in this case
The desire MAY then to be have the bacground OOF - a larger chip will make this occur
[a href=\"index.php?act=findpost&pid=82571\"][{POST_SNAPBACK}][/a]
Are you saying that with the same DOF, a larger format gives stronger OOF effects in the background? I do not see it. Instead, the relationship between DOF and background OOF effects depends only on distance from the subject.
So yes, changing from 50mm to 80mm in the same format, increasing ones distance from the subject 60% to keep the same FOV on the main subject, and keeping the same f-stop, the DOF stays the same, but the more distant background appears larger and blurrier, but that goes with change of position and thus of perspective.
If instead one changes from 50mm to 80mm staying at the same place, using a larger format so you get the same FOV, and increase aperture ratio (about one stop) to get the same DOF on the subject, then the more distant background appears the same size with the same amount of OOF blur.
Contrary to some comments in earlier posts, the relationship between DOF (OOF blur for subjects just far enough from the plane of exact focus to be visibly OOF) and stronger far background OOF effects, depends only on camera position relative to the subject and background.
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Howard,
that is one comparison that can be done of course, and you have done it many times. But as you know well, it involves changing the FOV of the full image recorded by the camera, and that is a rather uncommon situation. Most of us are far more interested in what happens when we hold the (uncropped) FOV constant.
It is just a matter of which quantities ones wants to hold constant, which depends on the photographic purpose for which the comparison is being done. My purpose is usually to record a given FOV using as much as possible of the available film or sensor area, so I usually increase focal length when I use a larger format.
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OK, I prefer to keep the degree of enlargement constant, and you prefer something else. FoV is a consideration in my selection of a lens and format, but has nothing to do with my calculation of DoF. Just optics and some personal choices for CoC.
As you know, FoV is dependant on format, focal length and focus distance. To keep FoV constant while changing format requires changing another variable to conpensate. Change format, change FoV. To get FoV back, change focal length or focus distance. Then to get DoF back, change f/stop. What ever. We just do not agree and likely never will.
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Howard, surely there are some facts on which we can agree.
First, DOF is not determined by format; it depends on numerous choices, and so DOF comparisons can only be made for specific combinations of choices.
With equal subject distance, image size on the print, and viewing distance (and equal viewer, with equal visual acuity etc.!),
1. If one chooses the same focal length and aperture, ones get the same DOF with any format.
2. If one chooses the same FOV and aperture ratio, one gets more DOF with a larger format.
And my personal favorite, not so much part of this discussion:
3. If one chooses the same aperture (meaning aperture size, measured by effective aperture diameter), one gets the same DOF.
Here by equal DOF, I mean that at every corresponding point on the prints, the circle of confusion (the disk into which the light from a single point of the subject is blurred by OOF effects) is the same size, so everything from DOF to extreme OOF effects in the far background are equal.
NOTE: do not confuse this more basic meaning of "circle of confusion" with its derivative use for a threshold value of the CoC diameter, occurring in some DOF formulas: my conclusions do not depend on any such choices of "CoC" value.
Do you disagree with any of these three claims? If not, then we have no significant disagreement on fact.
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Are you saying that with the same DOF, a larger format gives stronger OOF effects in the background? I do not see it. Instead, the relationship between DOF and background OOF effects depends only on distance from the subject.
...
If instead one changes from 50mm to 80mm staying at the same place, using a larger format so you get the same FOV, and increase aperture ratio (about one stop) to get the same DOF on the subject, then the more distant background appears the same size with the same amount of OOF blur.
Contrary to some comments in earlier posts, the relationship between DOF (OOF blur for subjects just far enough from the plane of exact focus to be visibly OOF) and stronger far background OOF effects, depends only on camera position relative to the subject and background.
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I think this is the point I still have some confusion on. My earlier thinking was that your position above was correct. To try and sum my earlier thoughts up -
If you equalize the field of view, subject distance, background distance, and print size - then shoot the same scene with smaller and larger formats, increasing the focal length and using a smaller maximum aperture as the format gets larger (increasing the aperture to the degree that calculated depth of field at the plane of focus remains relatively constant) - the resultant background blur should also remain constant.
But Sam's comments made me rethink this, and my own experience with MF and LF compared to 35mm made me question the above as well.
So, my own little test was to set up a fixed subject and background, and focus and view the same scene with three different systems (sorry, didn't go as far as I should have and make similar sized prints). I viewed the scene with a 50mm f/1.4 on 35mm, and 80mm f/2.8 on 6x6, and a 150mm f/5.6 on 4x5. Each have very similar fields of view and calculated depth of field, but to my eyes the larger formats defocused the background to a greater degree. I also saw what I was talking about earlier - the increased perceived separation of subject from background with the larger formats.
Now I know one big influence is that the size of the viewfinder or ground glass increases with larger formats, and that can sway my perception. However, even though I mentally tried to take this into consideration, I still saw more background blur with the larger formats. That is why I agreed with Sam on his point.
Not being a mathmatician I can't say whether the above conforms with optical theory. I did glance at an interesting website that tries to address the question but couldn't quite make sense of all the factors involved. Here's the website if you want to take a peek -
[a href=\"http://www.bobatkins.com/photography/technical/bokeh_background_blur.html]http://www.bobatkins.com/photography/techn...round_blur.html[/url]
I suppose one way to try to solve this would be to make prints and view the results for myself. I'm not particularly enthused about doing this, but I am curious about how to reconcile the two positions.
I still think that even if optical theory proves the first position right, Medium Format does exactly what Sam says it does - provides a sharper subject with adequate depth of field plus a nicely blurred background. My thought is that it may do this not because of the quantity of background blur but instead because of the reasons I outlined earlier (larger format = less lp/mm demand on the lens = better MTF performance at wider apertures = sharper subject with more pleasing background blur).
Sam is absolutely right - there is no way that a Canon 50mm f/1.4 or Nikkor 50mm f/1.2 on 35mm looks as good wide open as a Zeiss 80mm f/2.8 on MF.
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Howard, surely there are some facts on which we can agree.
First, DOF is not determined by format; it depends on numerous choices, and so DOF comparisons can only be made for specific combinations of choices.
With equal subject distance, image size on the print, and viewing distance (and equal viewer, with equal visual acuity etc.!),
1. If one chooses the same focal length and aperture, ones get the same DOF with any format.
2. If one chooses the same FOV and aperture ratio, one gets more DOF with a larger format.
And my personal favorite, not so much part of this discussion:
3. If one chooses the same aperture (meaning aperture size, measured by effective aperture diameter), one gets the same DOF.
Here by equal DOF, I mean that at every corresponding point on the prints, the circle of confusion (the disk into which the light from a single point of the subject is blurred by OOF effects) is the same size, so everything from DOF to extreme OOF effects in the far background are equal.
NOTE: do not confuse this more basic meaning of "circle of confusion" with its derivative use for a threshold value of the CoC diameter, occurring in some DOF formulas: my conclusions do not depend on any such choices of "CoC" value.
Do you disagree with any of these three claims? If not, then we have no significant disagreement on fact.
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I certainly agree with 1.
With 2., I also agree. Changing format does change the cropped FoV, if I keep the degree of enlargment unchanged. And yes, the FoV can be changed (preserved) if I also chose to change focal length or crop. It is the change in focal length changes the DoF. This seems like a very subtle point but important - it is the change in focal length that changes DoF not the change in FoV. If I changed to a larger format with the same focal length and degree of enlargement, I can retain FoV with a paper trimmer on the final print. No need to change focal length, degree of enlargement, or DoF. Merely paper size to get a larger photo on the paper. Now, if I just start with the smallest format and work my way up, this all works out.
And 3. is also true, same as above but changing f/stop to compensate for the change in DoF due to dhanging focal length.
I will not disagree that the way most (many? some?) people take photos is to find about the right spot for the tripod (focus distance) then select a focal length to fill the frame (zoom?) and then an f/stop. f/stop might even be selected by the camera or the photographer's notion of the "sharpest." Distance is usually then selected by the autofocus camera.
This last point could be important. From a DoF consideration, it is not neceaasry that any part of the subject be at the focus distance. A case would be some foreground elements at the edge of the Grand Canyon. Some stuff a few feet away, some stuff at essentially infinity. Auto focus picks something but maybe the DoF design would call for a focus distance of 100 feet. Does the usual auto focus camera user ever give this a thought?
If suddenly the photographer decided to change formats, then a new focal length would be selected to fill the new frame. New DoF. While true, the cause/effect relationships are not changed. I also believe that few photographers are aware of all the changes they are making when they zoom, let the camera focus and select f/stop, the effects of those changes, and, perhaps most important, why those changes have those effects. (No time to futz with all that stuff. I gotta capture the moment. I'll fix all that stuff later when I edit this moment in PS.) That is why some (many? most?) still think DoF is format dependant.
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Howard, surely there are some facts on which we can agree.
First, DOF is not determined by format; it depends on numerous choices, and so DOF comparisons can only be made for specific combinations of choices.
With equal subject distance, image size on the print, and viewing distance (and equal viewer, with equal visual acuity etc.!),
1. If one chooses the same focal length and aperture, ones get the same DOF with any format.
[a href=\"index.php?act=findpost&pid=82606\"][{POST_SNAPBACK}][/a]
I'm not so sure of 1, in the sense that I'm not so sure that two lenses of different design set to the same aperture would have the same depth of field even when mounted on the same camera and focused to the same distance. Sorry, but this is not obvious.
If someone wants to point us to a decent lens simuator, with a library of lens designs and target objects we could do some (simulated) experiments.
However, it would also be nice to see what the wide-angle shooters here think - is depth offield with a retrofocus lens on an SLR body the same in practice as that of a pseudo-symmetrical wide on a view camera ?
Edmund
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I'm not so sure of 1, in the sense that I'm not so sure that two lenses of different design set to the same aperture would have the same depth of field even when mounted on the same camera and focused to the same distance. Sorry, but this is not obvious.
If someone wants to point us to a decent lens simuator, with a library of lens designs and target objects we could do some (simulated) experiments.
However, it would also be nice to see what the wide-angle shooters here think - is depth offield with a retrofocus lens on an SLR body the same in practice as that of a pseudo-symmetrical wide on a view camera ?
Edmund
[a href=\"index.php?act=findpost&pid=82652\"][{POST_SNAPBACK}][/a]
The example you gave is changing more than focal length - "two lenses of different design."
All other things being equal, a fuzzy image will have more DoF simply because it becomes more difficult to perceive what is in and out of focus. Opposite is true for sharper images. Pin hole camers have large DoF for at least two reasons - very small f/sop and poor resolution (fuzzy).
True, the calcualted DoF would be the same, but the actual (applied) DoF could vary. Because I use the same lenses (even when changing lenses, I keep using the same ones over and over), I take these "real" variations into account when planning prints by adjusting CoC.
DoF, while something that can be calcuated, usually requires some fine tuning.
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If one chooses the same focal length and aperture, ones get the same DOF with any format.
Kornelius Fleischer, Zeiss's Marketing Manager, has said that two differently designed lenses of the same focal length may have different DOF even with the same format and the same aperture. He gives the example of the Hasselblad 250mm superachromat and the regular Hasselblad 250mm, at the same aperture the Superachromat has a shallower DOF.
It's just one of the "DOF myths" that he debunks, another example is that the theoretical DOF tables are computed only for the centre of the image, off axis different DOF rules apply but these are ignored by DOF tables.
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Kornelius Fleischer, Zeiss's Marketing Manager, has said that two differently designed lenses of the same focal length may have different DOF even with the same format and the same aperture. He gives the example of the Hasselblad 250mm superachromat and the regular Hasselblad 250mm, at the same aperture the Superachromat has a shallower DOF.
It's just one of the "DOF myths" that he debunks, another example is that the theoretical DOF tables are computed only for the centre of the image, off axis different DOF rules apply but these are ignored by DOF tables.
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You have kept focal length the same but changed designs - "two differently designed lenses of the same focal length". I think the effect is essentially changing CoC.
The superachromat lens has a smaller circle of confusion at the focal plane because it focuses all wave lengths of light better. The standard lens does not focus all wave lengths the same and produces a circle of confusion on the focal plane for the out of focus wave lengths.
A fuzzy image will have greater DoF than a sharp one, all other things being equal.
True, you are comparing the same focal length, but you have changed designs. I claim you are actually comparing the designs, not the focal length. The variables changed (compared) are the design, not the focal length.
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But I think it is the whole story.
My proof of this is if you stick a 645 lens on a 35mm body you get the same image - just less of it
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Hey! Morgan, I think I might like to employ you. I could offer you a good salary, then later when I cut it in half and you complain, I could say, 'but you've still got the same salary - just less of it.' I'm sure you would understand .
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I'm not so sure of 1, in the sense that I'm not so sure that two lenses of different design set to the same aperture would have the same depth of field even when mounted on the same camera and focused to the same distance.
[a href=\"index.php?act=findpost&pid=82652\"][{POST_SNAPBACK}][/a]
That is of course only an approximation, but a widely used and trusted one. Like all the standard formulas for DOF and the size of the circle of confusion on the focal plane, it is computed with the geometric optics approximation and for an on-axis subject, so chromatic aberrations and other lens aberrations make it inexact except for an imaginary aberration-free lens. (Gary and Howard have mentioned parts of this.)
However, such imprecisions are probably irrelevant to my original comment and questions.
For one thing, variations between lens designs are unlikely to be enough to offset the substantial differences in these approximations for minimum DOF between f/1.2 or f/1.4 portrait lenses in 35mm format and the fastest "portrait" lenses in the various current MF systems.
For another, it seems unlikely that there is significant systematic design induced DOF difference between 35mm and MF. Indeed, since the smaller format has to go to lower aperture ratios to get low DOF, and thus has to struggle more with aberrations, it would make sense if anything for 35mm format portrait lenses to be designed to get the lowest DOF that they can out of a given minimum f-stop.
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Kornelius Fleischer also mentioned (probably in the same thread I read, which Gary is quoting) that APO designs inherently have shallower DOFs than the non-APO equivalent. He went on to say this is why many Zeiss lenses are not APO designs---especially those that Zeiss designs for military use.
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Look here, and ant the two photos of the lady in front of the blue background (search for "sagittal") http://www.imx.nl/photosite/zeiss/test85/t004.html (http://www.imx.nl/photosite/zeiss/test85/t004.html)
Those two pictures look separated by 3 stops, and I don't think that such an experienced reviewer as Erwin Puts would have compared them if they were 3 stops different.
Also, I never wondered about portrait lenses, I wondered about extreme wides - eg a 28 mm gaussian and a 28mm retrofocus used with an MF digital back. In digital, as we all know, lane of focus effects are considerably magnified with respect to film !
Edmund
That is of course only an approximation, but a widely used and trusted one. Like all the standard formulas for DOF and the size of the circle of confusion on the focal plane, it is computed with the geometric optics approximation and for an on-axis subject, so chromatic aberrations and other lens aberrations make it inexact except for an imaginary aberration-free lens. (Gary and Howard have mentioned parts of this.)
However, such imprecisions are probably irrelevant to my original comment and questions.
For one thing, variations between lens designs are unlikely to be enough to offset the substantial differences in these approximations for minimum DOF between f/1.2 or f/1.4 portrait lenses in 35mm format and the fastest "portrait" lenses in the various current MF systems.
For another, it seems unlikely that there is significant systematic design induced DOF difference between 35mm and MF. Indeed, since the smaller format has to go to lower aperture ratios to get low DOF, and thus has to struggle more with aberrations, it would make sense if anything for 35mm format portrait lenses to be designed to get the lowest DOF that they can out of a given minimum f-stop.
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It's surprising how really bad most fast lenses are at full aperture. It seems to me that this really poor performance is masked by the extremely shallow DoF which, nevertheless, is not as shallow as it should be due to a lack of 'real' sharpness at the plane of focus.
An exception would be the Canon 200/1.8 which just happens to be the finest lens that Canon make (do they still make it?) and very expensive of course. At f1.8 and 40 lp/mm, contrast is still in the range of 60-70% right to the edges. Compare this with the Hasselblad Planar CF 80/2.8 which at f2.8 and 40 lp/mm has a best MTF response at the centre of just 40% falling off to a miserable 10% at the edges. If you came across a lens that had this sort of performance at f8, it would be fair to call it absolute crap.
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Look here, and ant the two photos of the lady in front of the blue background (search for "sagittal") http://www.imx.nl/photosite/zeiss/test85/t004.html (http://www.imx.nl/photosite/zeiss/test85/t004.html)
Those two pictures look separated by 3 stops, and I don't think that such an experienced reviewer as Erwin Puts would have compared them if they were 3 stops different.
Also, I never wondered about portrait lenses, I wondered about extreme wides - eg a 28 mm gaussian and a 28mm retrofocus used with an MF digital back. In digital, as we all know, lane of focus effects are considerably magnified with respect to film !
Edmund
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My original post specifically mentioned portrait lenses, and the much discussed need for large apertures for the sake of extremes of background blur in portraiture. So I will stay with that topics, as in your Sonnar 85/Summicron 90 "woman in blue" examples.
In those photos, the most likely explanation is the combination of substantially greater aberration blurring in the Sonnar (as Ray has suggested?) and the different perspective: the Sonnar is clearly closer to the subject, as the woman's image is larger despite the slightly shorter focal length. And the Sonnar image seems less sharp overall, on the woman and dress as well as the background, which is more evidence for its having significantly greater aberrations (or incorrect focus). Reducing focus distance will increase background OOF effects.
There is no doubt that under-corrected aberrations can soften backgrounds (and even main subjects) such as in "soft-focus" lens designs, in which under-correction of some aberrations is a deliberate design feature. Such design choices are irrelevant to my initial curiosity of comparing MF to 35mm format options, since soft-focus lenses exist for 35mm format too. Positioning of the aperture diaphragm can also affect the appearance of background blur, making the large "disks of confusion" harder or softer at the edges: I believe that macro and portrait lens designs often take opposite approaches on diaphragm placement, favoring maximum sharpness versus "nice bokeh" (softer backgrounds) respectively.
But in the "woman in blue" examples, the Sonnar 85 disks are clearly far larger, not just softer.
If such design differences could adequately soften distracting backgrounds and reduce DOF, why would photographers bother with f/1.2 or f/1.4 lenses for that purpose (as opposed to the main large aperture purpose of higher speed); they could just use soft focus lenses, some of which allow turning the "softness" on or off, or at least increasing and decreasing it. Probably there is more to the desire for "background softening" than that.
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An exception would be the Canon 200/1.8 which just happens to be the finest lens that Canon make (do they still make it?)
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No, the 200/1.8 was discontinued several years ago. Do you not remember the debate here as to whether Canon would soon replace it by something even better, or at least something as fast? Instead, technological changes like increased usable ISO and stabilization keep driving a trend away from the most extreme large aperture lenses.
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Do you not remember the debate here as to whether Canon would soon replace it by something even better, or at least something as fast? [a href=\"index.php?act=findpost&pid=83380\"][{POST_SNAPBACK}][/a]
Only vaguely, which is why I asked. My memory is not always at its best on issues like this when I am never likely to buy such a lens whether it's available or not .
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It is sometimes an advantage to have a lens that produces pleasing pictures with the out of focus parts of the scene rendered in a beautiful way. Absolute resolution, contrast at the image edges, or circles of confusion factors are second to the ability of a lens to make good pictures in my opinion. Rarely do I see a 'fast' lens make pleasing pictures wide open. My 210 f4 HC is not particularly fast but is wonderful wide open at f4. I'm glad not to be carrying around the extra glass for a 2.8 version only to shoot it at f4.
Damien.
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This is a very interesting thread. But....
Has anyone directly compared (e.g. portrait) a 35mm lens like the canon 85mm 1.2 with a MF setup with say an 80-120mm f2ish lens. I would love to see some direct comparisons at full or near full aperture.
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Only vaguely, which is why I asked. My memory is not always at its best on issues like this when I am never likely to buy such a lens whether it's available or not .
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I believe the replacement is ready, at least ready designed. They probably have simply not been able to find production capacity.
Edmund
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I believe the replacement is ready, at least ready designed. They probably have simply not been able to find production capacity.
Edmund
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It'll be interesting to see how it compares with the discontinued model, but unless there's a significant reduction in price, there's not much chance of my ever buying one. I suspect such lenses are so expensive, not only because it costs more to produce such high quality lenses, but because sales are not high and profit margins have to be greater. I guess manufacturing this new lens is not a priority for Canon. There are other lenses that they know will generate more profit, such as the 70-200L f4 IS.
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Negative refractive index???!
How does (speed of light in a vacuum)/(speed of light in the material) ever become negative? Or even become less than unity?
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Steve,
I'm reminded of your question because, not long ago, at the end of a day's trek in Nepal, during the evening's conversation when everyone huddles around the wood fire to get warm, the subject of digital camera's and the rapid development of technology came up.
One of the trekkers claimed to be a physicist, so I sounded him out on this interesting research on the concept of metamaterials with a negative refractive index.
He too immediately reacted as you did. How can the speed of light in any material exceed the speed of light in a vacuum?
After a bit of Googling, I get the impression that there's a ways to go before these new materials will be able to transmit light. The researchers are currently working on frequencies in the 1 to 3 micron wavelength. The wavelength of red light begins around 0.7 microns. However, I believe the same principle applies. Below is an extract from [a href=\"http://www.aph.uni-karlsruhe.de/ag/wegener/meta/meta.html]http://www.aph.uni-karlsruhe.de/ag/wegener/meta/meta.html[/url] .
Metamaterials and negative refractive index
The basic physics of "magnetic atoms" is quite simple: In order to obtain a magnetic response from a metal nanostructure the incident light field has to excite local currents circulating in loops (solenoidal currents). These currents in turn give rise to a magnetic dipole-moment. By properly designing the metal nanostructure, one can obtain a resonant enhancement of the local currents leading to a strong magnetic response and potentially a negative magnetic permeability.
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This is a very interesting thread. But....
Has anyone directly compared (e.g. portrait) a 35mm lens like the canon 85mm 1.2 with a MF setup with say an 80-120mm f2ish lens. I would love to see some direct comparisons at full or near full aperture.
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There is a comparison of the Canon 5D with the 85 f1.2 mk II against the Hasselblad H2 with 39' back and 100 f2.2 in the latest edition of swedish magazine proffsfoto. They come out pretty similar, but the MF system wins on most aspects.
-axel.
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I would love to see the comparisons. Let me ask another question. If you were using a Hasselblad H system and could select the best medium focal length (80 to 150mm) lens for DOF, OOF, and Bokeh, which one would you select. I have tried to read comparisons on the web after doing a google search but nothing really substantial comes out of it. mark
There is a comparison of the Canon 5D with the 85 f1.2 mk II against the Hasselblad H2 with 39' back and 100 f2.2 in the latest edition of swedish magazine proffsfoto. They come out pretty similar, but the MF system wins on most aspects.
-axel.
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I would love to see the comparisons. Let me ask another question. If you were using a Hasselblad H system and could select the best medium focal length (80 to 150mm) lens for DOF, OOF, and Bokeh, which one would you select. I have tried to read comparisons on the web after doing a google search but nothing really substantial comes out of it. mark
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It would be great to throw the 50-110 lens in this comparison group. It seems so many shooters use this as a starter lens for the H1 because of it's versatility. With the Canon and Nikon lenses there are many fixed lenses that provide so little improvement over zoom lenses these days that it is often not worth the effort to switch back and forth.
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I can state as a general purpose lens, this zoom is absolutely outstanding. It is the best zoom i have used period. It is tack sharp even at full aperture. the bokeh is nothing special but I suspect this may be the fuji vs zeiss factor. I went hiking in the colorado mountains and with one exception, this lens remained on the camera the whole time. It is big and heavy though and I almost never use it other than on a tripod. So i am trying to find one lens for those narrow DOF shots or I am going to go back to a canon 85 1.2. Mark
It would be great to throw the 50-110 lens in this comparison group. It seems so many shooters use this as a starter lens for the H1 because of it's versatility. With the Canon and Nikon lenses there are many fixed lenses that provide so little improvement over zoom lenses these days that it is often not worth the effort to switch back and forth.
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I believe the replacement [for the discontinued Canon 200/1.8--BJL] is ready, at least ready designed. They probably have simply not been able to find production capacity.
[a href=\"index.php?act=findpost&pid=92278\"][{POST_SNAPBACK}][/a]
That seem very unusual: discontinuing a product several years before a replacement is ready. Can you reveal your source for that belief? Forgive my skepticism, but a lot of people confidently but incorrectly predicted the imminent arrival of a replacement back when the 200/1.8 was discontinued: hopes got transformed into claims of fact back then, as often happens.
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Your scepticism is well founded as Canon hasn't released an updated 200/1.8 while Nikon released a spectacular lens in the same class. But I see no reason to retract my statement. I was told there was a replacement - what happened to it is anybody's guess. BTW, I own a 200/1.8. Nice lens.
Edmund
That seem very unusual: discontinuing a product several years before a replacement is ready. Can you reveal your source for that belief? Forgive my skepticism, but a lot of people confidently but incorrectly predicted the imminent arrival of a replacement back when the 200/1.8 was discontinued: hopes got transformed into claims of fact back then, as often happens.
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... Canon hasn't released an updated 200/1.8 while Nikon released a spectacular lens in the same class. But I see no reason to retract my statement. I was told there was a replacement - what happened to it is anybody's guess.
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We can only wait and see what actually happens this year: one side of me favors offering high end f/2 telephoto primes at up to the longest focal length at which this is economically viable. (And Nikon once had a 300/2: [a href=\"http://www.cameraquest.com/nf3002.htm)]http://www.cameraquest.com/nf3002.htm)[/url] This is based on a guess that about f/2 is the fastest that a long telephoto lens can be with acceptable control of aberrations and such, and the idea that extra lens speed allows the use of higher sensor resolution (roughly, smaller photo-sites) under a given combination of lighting speed needs, giving more telephoto reach with a given focal length. Even if that sometimes involves significant cropping, or changing to a smaller format body for long telephoto work.
The only signs of such pushing at telephoto lens speed limits lately are the lens speed Nikon 200/2 and Olympus 150/2, and maybe one could count the recent fast zooms from Olympus, 35-100/2 and 90-250/2.8.
In one sense, the Nikon 200/2 is not in the same class as the as the Canon 200/1.8 when used on current Canon high end bodies, as the Nikon can be used with higher resolution sensors: 5.5 microns compared to 7.2 to 8.2 microns. The high end Nikon lens-body combinations give higher angular resolution of subject detail, comparable to about 260mm on a 1DsMkII or 300mm on a 5D or 1DMkII. That puts Nikon's offering in a different market position for now, more like that of a Canon 300/2.8, which is I believe a far better seller than the Canon 200/1.8 was.
This changes if a 200mm is used with the new 400D, but a real increase in demand for a Canon 200mm faster than f/2.8 will probably not occur unless and until Canon offers a high end model with pixel spacing comparable to 5.5 microns. Maybe something like a 16MP model in the "1D" format, to replace the 1DMkII?
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BJL,
I don't know if you ever held a Canon 200/1.8. If you had you'd know why the sales are so slow, and you wouldn't dream of mounting it on a Rebel
By the way, this lens has an interesting fault, the bayonet lock disengages somehow, and the lens disengages spontaneously. I've had mine do that, and people on RG complained too. It seems to be the only Canon lens to do that, luckily.
Edmund
We can only wait and see what actually happens this year: one side of me favors offering high end f/2 telephoto primes at up to the longest focal length at which this is economically viable. (And Nikon once had a 300/2:
That puts Nikon's offering in a different market position for now, more like that of a Canon 300/2.8, which is I believe a far better seller than the Canon 200/1.8 was.
This changes if a 200mm is used with the new 400D, but a real increase in demand for a Canon 200mm faster than f/2.8 will probably not occur unless and until Canon offers a high end model with pixel spacing comparable to 5.5 microns. Maybe something like a 16MP model in the "1D" format, to replace the 1DMkII?
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