Luminous Landscape Forum
Equipment & Techniques => Digital Cameras & Shooting Techniques => Topic started by: Wayne Fox on October 31, 2009, 04:25:32 pm
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Was checking out the s90 and G11 the other day, and decided to do a quick noise test for fun.
All images taken on full manual (including focus). Processed in LR 3beta, with all noise reduction and sharpening turned off. The only thing I did was use use the white balance tool on the medium gray. Base exposure was IS0 100 for 1 second at f/8, aperture was kept constant and shutter speed varied as ISO was increased. A 100 pixel square was cropped from each image and the resulting grid is a 1 to 1 pixel ratio on the screen.
Working with the files, there is a definite and obvious quality difference between the GF1 and the smaller cameras, they were more like the 7d files. My personal opinion is that other than perhaps niche uses such as macro and underwater mentioned in another thread, the G11 doesn't have much to offer. The s90 delivers very similar quality, including similar noise performance and will actually fit in your shirt pocket. If the s90 isn't good enough, moving to the G11 won't get you all that much (as far as image quality). You are better off moving to the GF1, a camera which continues to impress me. Canon should consider a larger sensor version of a G11 for the G12. I'm going to take a s90 out for a day or two and shoot it alongside a 7d just for fun.
Handling of the G11 was odd at first ... the thumbwheel is smaller and a little awkward. I kept hitting the wrong buttons. Once I realized it protrudes further and you need to move it on the side rather than on the top it wasn't too bad. The articulating LCD is a nice feature, and the improved noise might make an upgrade worthwhile to some, but that's a pretty pricey upgrade to get about 1 more stop of noise performance and a swiveling LCD.
the grid is a little large, 1.5 mb ... I saved it at highest quality jpeg to minimize possible distortion of the noise from jpeg artifacts.
[attachment=17613:FullScene.jpg][attachment=17614:Combined_Detail1.jpg]
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Thanks, Wayne - that's useful.
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I wish that someone smarter than me would explain the impact that the difference in exposure levels might have on noise measurements: in every instance, G11/S90 appear overexposed relative to other cameras.... the most so vs. G10, then 7D, and even vs. GF1. The same was evident in Michael's test as well. So, the question again is: what impact (if any) does it have on noise measurement?
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I wish that someone smarter than me would explain the impact that the difference in exposure levels might have on noise measurements: in every instance, G11/S90 appear overexposed relative to other cameras.... the most so vs. G10, then 7D, and even vs. GF1. The same was evident in Michael's test as well. So, the question again is: what impact (if any) does it have on noise measurement?
I hear you. I plan on testing this further because in my case the camera metering system was not invoved. However I am unsure if the difference could be due to the camera profiles used by lightroom.
Obviously if you made an iso adjustment on the g11 to match the g10 density the noise improvement would be more significant.
Like you I need someone smarter than me to help me understand what's going on.
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The S90 and G11 have the very same sensor, so it would be a surprise if their noise characteristics were different. In fact, my measurements confirm that they are the same.
Rawnalyze supports the G9, G10, G11, S90 and SX1 IS. If someone wants to make raw data analysis, like exposure, clipping, of the G11 and S90, then one should write that to me, for I added the support in the newest version, which is not uploaded yet.
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Thank you, Wayne. This just adds to my interest in the GF1. I appreciate the effort you went to to post this.
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Interesting, thanks for the test. No real surprises -- the s90 and G11 images are close enough to be identical, and are slightly better than the G10 files. I'll be interested to hear your thoughts after a couple of days of shooting with the s90.
The files from the GF1 appear to have chrominance noise reduction, perhaps that's done in-camera to the raw files? They are the only photos to be a nice overall neutral gray with no color noise.
The 7D files look pretty good for so many pixels on an APS-C sensor.
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Thanks = clearly shows the reduced noise of the G11 compared to the G10.
I tested my G10 when I first got it. I found that it was sharpest wide open and /or one stop down (this is contrary to most wide and mid-focal length lenses for 35mm). It was noticeably softer at f8 at all focal lengths. This is not surprising given diffraction. You would get more resolution out of the G10 and G11 with a larger aperture than the one you used for testing.
Cheers
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Was checking out the s90 and G11 the other day, and decided to do a quick noise test for fun.
..... Canon should consider a larger sensor version of a G11 for the G12.
Hi Wayne,
I frequently read similar comments, apparently implying that noise performance of a compact camera can be improved simply by slotting in a larger sensor.
Unfortunately it doesn't work that way, as the amount of light gathered by the sensor is, strictly speaking, set by the size (actually absolute aperture) of the lens, not by the size of the sensor as commonly believed.
In other words, to gain any appreciable benefit from redesigning a G11 with a larger sensor would require a proportionally larger lens, which could easily be done, but then the G11 would no longer be a compact camera.
As I own a G10, I found your post interesting.
Colin
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Unfortunately it doesn't work that way, as the amount of light gathered by the sensor is, strictly speaking, set by the size (actually absolute aperture) of the lens, not by the size of the sensor as commonly believed.
How big is the image circle relative to the G11 sensor? Do you have that info?
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How big is the image circle relative to the G11 sensor? Do you have that info?
I'm not sure what you are driving at. As the G11 uses a non-removable lens, you can be sure that the lens has been well optimized for use with the G11 sensor, and that the "image circle" is not appreciably larger than it needs to be to fill the sensor. Regardless of that, everything I said previously would still be correct, even if the image circle was much larger than the sensor.
Can you enlarge on your thoughts?
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I'm not sure what you are driving at. As the G11 uses a non-removable lens, you can be sure that the lens has been well optimized for use with the G11 sensor, and that the "image circle" is not appreciably larger than it needs to be to fill the sensor. Regardless of that, everything I said previously would still be correct, even if the image circle was much larger than the sensor.
Can you enlarge on your thoughts?
I'll stick to facts ... the G7 had a sensor that was 1/1.8 " (7.18 x 5.32 mm, 0.38 cm²) and the G9 had a sensor that was 1/1.7 " (7.60 x 5.70 mm, 0.43 cm²) ... the lenses are the same ...
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I'll stick to facts ... the G7 had a sensor that was 1/1.8 " (7.18 x 5.32 mm, 0.38 cm²) and the G9 had a sensor that was 1/1.7 " (7.60 x 5.70 mm, 0.43 cm²) ... the lenses are the same ...
I'm a stickler for facts also, but still don't understand what you are driving at.
I previously wrote:
Unfortunately it doesn't work that way, as the amount of light gathered by the sensor is, strictly speaking, set by the size (actually absolute aperture) of the lens, not by the size of the sensor as commonly believed.
This statement is true quite independently of the size of the image circle projected by the lens. Let's see what actually happens if we attempt to double the size of the sensor in a G11, for example. Initially, assume the original G11 lens is completely unaltered.
Even making the favourable assumption that the new double-size sensor is filled by the original lens, we now immediately have the problem that the field of view has been doubled. In other words, while the original camera had a focal length range from 28-140 mm (35mm equivalent), our "new improved" G11 with double-size sensor will have a focal length range from 14-140mm (35mm equivalent). Bugger! So much for the totally trivial upgrade where the sensor size is doubled but the original lens is used.
OK. To keep the zoom range of the camera the same with the larger sensor, we will need to double the focal length of the lens. No problems, we can easily do that. Now we come to the tricky part. The original G11 lens was F2.8-4.5, and we need to maintain this speed of lens or there will be no net benefit from enlarging the sensor. Recall how f-numbers are defined:
f-number = (Focal length)/(Aperture Diameter)
As discussed, we have been forced to double the focal length to maintain the original zoom range. From the above definition of f-number, the only way to maintain the same f-number, or "speed" of lens, is to also double the absolute aperture diameter of the lens. Double bugger!! What that actually means, is that in order to obtain any benefit from doubling the sensor size, we have had to simultaneously double the size (= absolute aperture) of the lens, which is exactly consistent with what I said in the first place.
The above example is an illustration of a broader fact of optics, which I will now restate more precisely.
For a given field of view, the amount of light (= total number of photons) gatherd by the lens, and delivered to the sensor, is set by the absolute aperture diameter of the lens, NOT by the size of the sensor as such.
Note that the sensor size does not, fundamentally have anything to do with how much light is collected by the sensor, despite popular myth, and quaintly misleading analogies of holding bigger buckets (pixels) out in the rain to collect more raindrops (photons).
However, as it turns out, the sensor size is an indirect player in how much light can be gathered onto the sensor with physically realizable lenses, and I can talk about that in a later posting.
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I'm a stickler for facts also, but still don't understand what you are driving at.
Not that complicated ...
When Canon upgraded the G7 to the G9, it appears that they added a larger sensor while keeping the lens the same.
That's all.
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Col, that argument is logically flawed, and actually quite factually wrong.
The simplified (but factually correct) relationship between irradiance and FoV/Aperture is:
Irradiance (I, in W/m^2) = ApertureArea (A in m^2) times FoV (steradians)
Irradiance is total light effect on the sensor surface
ApertureArea is (FL/(2xFno))^2 x pi
FoV (as in solid angle) is of course deduced from the sensor area and the lens focal length.
Hence - same field of view, same ApertureArea (note "ApertureArea", not F/no!) - will always result in the same number of photons per second hitting the sensor surface, no matter what size the sensor is. So far all is well. To reach this equivalence, you have to increase Fno as the sensor area grows - a bigger sensor must use a longer FL to keep FoV the same, longer FL needs higher Fno to keep ApertureArea the same.
5mm sensor 20mm lens with an F/2 aperture has the same FoV and ApertureArea as a 10mm sensor with a 40mm lens at F/4. FoV is the same, ApertureArea is the same, irradiance is the same.
If you keep Fno and FL, and increase sensor area, FoV increases, and irradiance increases. This is what happens if you put the same lens on two slightly differently sized sensors. More light hits the bigger sensor surface.
What you MIGHT be thinking of is "exposure", which is a totally different metric. Exposure is always dictated by F/no, as it is a parameter locked to a certain predetermined area. It doesn't matter if you increase that area - exposure per area unit will be the same.
But "exposure" and "light amount (irradiance)" are not interchangeable metrics. And "light amount" is what dictates noise over the frame, not exposure (which is what the disussion started with, I suppose).
@Wayne : Thanks for you work, btw. Interesting. I know how much work these "controlled test" take to pan out into something presentable and usable... :-)
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Hi Suede,
Thank you for your detailed response, though I still stand 100% behind everything I said.
To be honest, I'm not sure which of my statements you agree with, and which you disagree with, which makes it very difficult for me to respond. Can you tell me exactly which of my statements you believe to be factually wrong, and why the argument is logically flawed?
As I wished to keep my explanation simple, I did not spell out a few minor details. For example, when I said that the amount of light gathered by the lens is set by the absolute aperture diameter of the lens, I didn't mean that the gathered light is literally proportional to the aperture diameter. Obviously the amount of gathered light is proportional to the area of the aperture, which in turn is a function of (ie, set by) the aperture diameter.
Apparently you agree exactly with at least one of my key statements:
I wrote:
For a given field of view, the total number of photons gathered by the lens, and delivered to the sensor, is set by the absolute aperture diameter (actually aperture area) of the lens, NOT by the size of the sensor as such.
You wrote:
Hence - same field of view, same ApertureArea, will always result in the same number of photons per second hitting the sensor surface, no matter what size the sensor is.
Given our agreement on this point, do now you agree with my original statement, from where the whole discussion started:
… to gain any appreciable benefit from redesigning a G11 with a larger sensor would require a proportionally larger lens, which could easily be done, but then the G11 would no longer be a compact camera.
You wrote:
What you MIGHT be thinking of is "exposure", which is a totally different metric. Exposure is always dictated by F/no, as it is a parameter locked to a certain predetermined area. It doesn't matter if you increase that area - exposure per area unit will be the same.
But "exposure" and "light amount (irradiance)" are not interchangeable metrics. And "light amount" is what dictates noise over the frame, not exposure.
Actually, irradiance is NOT the same as 'light amount' or 'total light effect', and you made this same mistake right at the start of your posting as well. Irradiance is the number of photons/second received per unit area, on a surface. However, you are correct in stating that the image noise is related to the total number of photons landing on the detector or, to be more precise, the total number of detected photons. I think we all agree that to reduce image noise, we need to increase the total number of photons gathered by the lens, and delivered to the detector.
In summary, I completely stand behind everything I said. If you still disagree with anything I have said, can you state exactly what it is you disagree with, otherwise I find it difficult to respond in a concise and well structured manner.
Cheers,
Col
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Okies, we'll try to sort this out... :-)
First quote (yours)
Field of view is given by the combination of the lens and the sensor. Given that FoV is the same, and we don't change lenses, sensor has to be the same. Sensor = sensor if sensor is the same? System lockdown. I got confused by you seemingly using the words "the lens" as in meaning "the one and only used lens for any combination". Same lens, same aperture, bigger sensor > more light flux. Probably no conflict here other than the use of words.
Second quote (mine)
FoV x Aperture Area = Light amount.
I thought that I was clarifying that bigger sensor > longer FL > same aperture area (higher F/no) > same light amount. Indicating exactly the same as what you probably meant by the first quote; that ApertureArea x FoV > light amount. Se comment on first quote.
Third quote (yours)
Depends on how much larger sensor... A small amount would probably not matter much. But in essence, no conflict. The lens is probably planned to be "just enough".
Fourth quote (mine)
Yes, my mistake. Correct use of units should be "radiant flux". To doublecheck - I mean total amount of light on [sensor surface per second] - a unit that needs no area dimension, just a flux.
Most circles around the first quote, where I (apparently) misunderstood your use and intention with the words "the lens". If I hadn't got stuck on that I probably wouldn't have reacted at all, and probably would have read more carefully. And then I messed up by using the wrong (area unit based) unit where I meant an area-less unit. I'll make the bad excuse of mixing one too many languages up in the same session (wrote on some German and Swedish boards just before/during this) too late in the day (or rather, at 5 in the morning)... :-)
I was probably ticked of by erroneously reading your post as "another idiot who thinks that 50F/1.4 makes a 100F/1.4 on 4/3-format..."
- in which I was wrong I see by reading a bit more carefully.
Cheers... :-)
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Okies, we'll try to sort this out... :-)
Thanks for that - I think we now pretty much agree on the theory.
However, I think you may have missed the broader point that I was trying to get across in the first place, so I'll briefly summarize that now.
There is a commonly held misconception that the image noise performance of a compact point-and-shoot camera can be significantly improved simply by using a larger sensor, and presume that Wayne had this notion in mind when he suggested that Canon should use a larger sensor than the 1/1.7" in the G11, if and when they bring out a G12.
From my reading on the net, there is an almost universally held myth (or at least, highly misleading explanation) that a larger sensor collects more light simply because it has a larger surface area, and the net abounds with analogies where if you place a larger bucket (sensor) in a rain of photons, then "obviously" the larger bucket (sensor) will catch more photons. It is only a small step from there to conclude that if camera manufacturers had the good sense to fit larger sensors into compact cameras, then more light would be collected, with a subsequent reduction in image noise.
The problem with this reasoning is that, depite popular myth, the amount of light falling on the sensor does not fundamentally have anything to do with the size of the sensor, but is is instead set by the aperture area (and therefore physical size) of the lens. We both agree fully on this point. In your words:
(Amount of light striking sensor) = (Field of view) x (Aperture Area)
Note that the size of the sensor does not come into it, exploding the myth that the sensor size is directly responsible for collecting more light.
Once it is understood that it is actually the physical size of the lens (aperture area) that determines how much light is incident on the sensor, rather than the sensor size, it becomes obvious why camera manufacturers do not waste their time putting large sensors into compact cameras that must necessarily have compact lenses, hence my previous example of how essentially nothing useful is achieved if you hypothetically try to improve the performance of a G11 by simply slotting in a lager sensor.
While nothing I have said to date is incorrect, it turns out that a larger sensor permits the use of larger lenses, which therefore gather more light onto the sensor and decrease image noise, which is a very good reason why SLR and professional camera use larger sensors. As yet I have not told the whole story, but have probably monopolized and distorted Waynes thread for long enough. Sorrry about that, Wayne.
I should probably start a new thread entitled "Myth of the large sensor compact camera", and continue the discussion
Cheers, Col
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"Myth of the large sensor compact camera"
May I ask you to compare the noise characteristics of the Leica X1 and the Canon G11 and then explain from where any difference arises?
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Hi Wayne,
I frequently read similar comments, apparently implying that noise performance of a compact camera can be improved simply by slotting in a larger sensor.
Unfortunately it doesn't work that way, as the amount of light gathered by the sensor is, strictly speaking, set by the size (actually absolute aperture) of the lens, not by the size of the sensor as commonly believed.
In other words, to gain any appreciable benefit from redesigning a G11 with a larger sensor would require a proportionally larger lens, which could easily be done, but then the G11 would no longer be a compact camera.
As I own a G10, I found your post interesting.
Colin
Maybe my off the cuff remark about Canon and the G11 wasn't explained as fully as I should have. I wasn't trying to imply they should just shove a bigger sensor in there. What I was implying is the camera really isn't very attractive anymore, considering the much smaller s90 pretty much does everything the G11 does, and a little bit larger GF1 gains a substantial amount of system flexibility and image quality. The g11 seems irrelevant at this point ... perhaps it's time canon punts on the thing and actually tries to develop an larger sensor but very small bodied rangefinder or EVF system ... this seems to be the hot category right now.
My logical side is puzzled by your statements however. While it is true the amount of available light of the sensor is limited by the aperture of the lens, the size of the sensor should have some correlation to the ability to gather light. Each sensor site is covered primarily by non light gathering area ... I believe only 10% of a CMOS sensor site is actually light sensitive, whereas about 30% of a CCD sensor site is light sensitive.
If we increase the sensor size it increases the area of that light sensitive portion, and thus increases the ability of the sensor site to record light. The increase in sensor site size doesn't increase noise in a proportionate amount, leaving me with the conclusion that a well designed sensor that is 5 times larger has a light gathering advantage vs. noise against a sensor that is substantially smaller. I assume there comes a point of diminishing return, but I believe the difference between G11 and the micro 4/3rds sensors is significant enough to help with improved noise.
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My logical side is puzzled by your statements however. While it is true the amount of available light of the sensor is limited by the aperture of the lens, the size of the sensor should have some correlation to the ability to gather light. Each sensor site is covered primarily by non light gathering area ... I believe only 10% of a CMOS sensor site is actually light sensitive, whereas about 30% of a CCD sensor site is light sensitive.
If we increase the sensor size it increases the area of that light sensitive portion, and thus increases the ability of the sensor site to record light. The increase in sensor site size doesn't increase noise in a proportionate amount, leaving me with the conclusion that a well designed sensor that is 5 times larger has a light gathering advantage vs. noise against a sensor that is substantially smaller. I assume there comes a point of diminishing return, but I believe the difference between G11 and the micro 4/3rds sensors is significant enough to help with improved noise.
You are absolutely correct. Larger sensors or, more precisely, sensors with lower pixel density, generally have a higher 'fill factor", meaning the light sensitive area is a higher proportion of the total area. This is a useful second order advantage of larger sensors. Another benefit of larger sensors is the superior dynamic range on account of the larger pixel full well capacity, though this advantage is only available when there is "light to burn" and the lowest ISO can be used.
However, the main reason why a 4/3 sensor equipped camera such as the GF1 outperforms a G11 for image noise in low light, is because the GF1 has a much larger lens (greater aperture area) to gather more light, consistent with all the previous discussion.
Let's see whether I'm talking BS. The G11 weighs 355gms including lens, and the camera (with lens) is 112x76x48mm. The lens of the GF1 is HUGE by comparison. The nearest matching GF1 lens in terms of zoom range is the Panasonic/Leica 14-50mm, and at 434gms, the lens alone weighs more than the entire G11! Dimensionally the lens is huge by comparison as well, being 74mm in diameter and 93mm long. Yep, everything I have said adds up in the real world ....
but I believe the difference between G11 and the micro 4/3rds sensors is significant enough to help with improved noise.
Certainly the difference between the G11 and 4/3 lenses is significant enough to help with improved noise.
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May I ask you to compare the noise characteristics of the Leica X1 and the Canon G11 and then explain from where any difference arises?
Most certainly.
The X1 will whip the pants off a G11 for image noise in low light.
As per Wayne's last posting, a small part of the X1 low noise superiority can be attributed to the higher pixel fill factor of the larger sensor. However, most of the substantially lower noise of the X1 will be due to the larger aperture area of the X1 lens. Let's see if that prediction is true.
The X1 sports a prime lens of L=24mm (actual), and F2.8. Therefore the effective aperture diameter is D = L/f = 24/2.8 = 8.6mm
The "35mm equivalent" focal length is 36mm
The G11 sports a zoom lens of L=6.1-30.5mm (actual), L=28-140mm (equivalent) and F2.8-4.5 Therefore the effective aperture diamter ranges from 6.1/2.8 = 2.2mm at the wide end, to 30.5/4.5 = 6.8mm at full telephoto.
At the same equivalent focal length (ie, FOV) as the X1, 36mm, which is very close to the wide end of the G11, we could roughly estimate the effective G11 aperture as about 2.5mm at 36mm effective focal length.
OK. At the same FOV, the X1 has an aperture diameter of 8.6mm, while the poor old G11 has only 2.5mm. In terms of aperture areas, the X1 is therefore 58 mm^2, while the G11 is only 4.9 mm^2 Therfore, the aperture area of the X1 is a whopping 12 times larger than the G11. Wow!!! I should damned well hope the X1 would give a lower noise image, with 12 times as much light being gathered by the lens and dumped on the sensor.
Once again, it is seen that a large aperture lens is required to collect a large amount of light, but there is one last question to be answered re the X1. The lens on the X1 is NOT particularly big or heavy, so how does it manage to have a much larger aperture diameter than the similar sized lens of the G11? Simple. The G11 is a fixed-focal-length lens whereas the G11 sports a x5 zoom range. If you can live without zoom, (I can't), then prime lenses really are MUCH smaller than zoom lenses, and this is the only "trick" to the X1. Relative to an SLR I guess Leica also save a bit of bulk and weight by making the lens non-removable, but this makes the fixed-focal-length lens even more limiting.
In the end, it get's down to this. Large sensors can produce wonderful results if you can throw enough light at them. To do this, you need a lens with a large aperture diameter, which means either a physically large zoom lens, or else use a prime and put up with no zoom. No exceptions, unfortunately.
Therefore the holy grail of a G11 style compact camera with useful zoom range, and a large APS sensor to supposedly give low noise as per an SLR, is simply not going to happen.
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Lets compare the gf1+20/1.7 to the g11
1) One thing not to forget is DOF. While sometimes shallow DOF is nice for isolating the subject - very often a certain amount of DOF is wanted to have everything sharp which should be sharp. I am talking about a group portrait, a mother with daughter, a portrait from an certain angle, macro, interieurs, etc etc.
To get similar DOF with a 4/3 and a small sensor one has to stop down the 4/3 lens at least 1-2 steps (I assume probably more).
From thispoint of few one could argue that the smaller the sensor the further can I open the f-stop and the lower can I keep the ISO.
2) The 20/1.7 as far as I know doesnt have IS while the g11 has it
3) the g11 has a zoom, the 20 is a prime
conclusion from 1) and 2) the low light advantage of a gf1 over a g11 is mainly valid for moving subjects and shallow DOF images. Otherwise one could use the g11 at least at 2 steps lower ISO because of the larger DOF and the IS
For me the idea of a 20mm prime was to restricting. I found that out with the dp2 allready which also has a 40mm FOV.
If I had to live with one focal length it would need to be 35mm like the x1 for example, but still I really like the flexibility of the zoom in the g11.
Sometimes 28mm wide angle is just really a nice to have, and sometimes its also nice to be able to zoom to 100 or 140 mm.
If I had to use this camera as my 1 and only I would prefer a 4/3 camera (probably the GH1) and use it sometimes with the prime and sometimes with a zoom.
But as an additional small camera I much prefer the g11-style of camera, even if the cost was the same as a 4/3 camera. Another nice thing is 1/2000 flash -sync.
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Wayne - sorry for hijacking your thread, but I do think the discussion is relevant to the theory, just as well as your comparison was beautifully coherent to the practical side of it.
Col:
Then I have nothing to object to about the your conclusions, except for the way you word it. Let me try to explain why...:
The physics of it is correct, but it is a very confusing way to try to explain it (as photographers are mostly F/no "thinking"). In the middle ranges of focal lengths, size of the optics doesn't really increase that much when you increase sensor size and want to keep the available field of view fairly constant - IF you keep aperture area constant. But to get an increased light amount to hit the sensor (which was why you wanted a larger sensor) you have to increase aperture area - which you do by keeping F/no constant! Much of the "normal" confusion lies here.
Small sensor, small focal length at F/4 > X amount of light per second.
2x sensor, 2x focal length, still at F/4 > 4X amount of light per second. Same FoV, Half DoF, half noise.
- And the logical explanation for the above: You keep field of view the same, but the aperture area increases with 4x. This system will be bigger, and heavier. As compared to:
Small sensor, small focal length at F/4 > X amount of light per second.
2x sensor, 2x focal length, at F/8 > Still X amount of light per second. Same FoV, same DoF, same noise - as the aperture area/FoV is kept constant.
In this case the lens doesn't HAVE to get that much larger, but it will most oftenly get a bit longer physically. My 50F/1.4 isn't that much smaller than my 100F/2.8. In fact, it's heavier, and has a larger outside diameter.
So I get what you're saying, and it's ok in my book. You can't just pop a 24x16mm sensor in a compact camera and expect it to "work" as in "gathering more light". But on the other hand I'm all for a slightly smaller zoom-range, a slightly larger sensor and keeping size increase to a minimum... And you can make small compact lenses wickedly sharp ("sharp" used in the sentence where "good" maybe had been more in line with what I was thinking, but more commonly misunderstood) these days - !
Most people do no direct connection between aperture area and the F/no, and that's the confusion.
The 4/3 system is still hampered by it's ancestral heritage - the systems could made even smaller. Their longer, large aperture zooms are in fact 36x24mm optimized zooms with a slightly smaller diameter - with a wide-converter built in to the rear end of the lenses to adapt the lens to the 4/3 size sensor... (WC is the opposite to TC's, and yes, they do exist. Very abundantly in the astro-photography community in fact...). They could be at least 40% smaller if they were developed from "scratch", or just downscaled originals - which I have NO idea why they didn't do from the start. It probably (as usual) has something to do with developing- and production run costs...
But I'm very much a "prime" person, I rarely find uses for superzooms or even anything above the normal 3x zoom lenses. Larger sensors in compacts with smaller zoom ratios would fit me perfectly - but I'm aware that those products may be hard to sell in quantities enough to be lucrative to the maker.
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(Amount of light striking sensor) = (Field of view) x (Aperture Area)
Note that the size of the sensor does not come into it, exploding the myth that the sensor size is directly responsible for collecting more light.
The problem with your argument is that you're assuming FOV is held constant for a lens. If the lens projects a large enough image circle to cover both sensors, then the FOV will not be constant, and the larger sensor will collect more light. Your equation also leaves out one rather important variable: exposure time. If two sensors used different lenses that had the same aperture area for the same FOV, that would imply that the larger sensor was using a longer lens at a smaller f/stop. In that case, the larger sensor would be using a longer exposure time, so it would still collect more light.
While nothing I have said to date is incorrect, it turns out that a larger sensor permits the use of larger lenses
The larger sensor doesn't just 'permit' a larger lens, it requires a larger lens. It's not like you could stick a 4/3 sensor behind the G11 lens, the image circle is far too small. Sensor size and aperture area are linked. So what you say about aperture area is technically correct, but amounts to semantic quibbling that is essentially meaningless regarding the relationship between sensor sizes and image quality.
It's true that using the G11's lens with a larger sensor wouldn't make much sense, but I don't think that's what Wayne was suggesting.
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In previous postings, I wrote:
... the sensor size does not, fundamentally, have anything to do with how much light is collected by the sensor, despite popular myth ....
However, the sensor size is an indirect player in how much light can be gathered onto the sensor with physically realizable lenses ....
While nothing I have said to date is incorrect, it turns out that a larger sensor permits the use of larger (aperture) lenses, which therefore gather more light onto the sensor and decrease image noise, which is a very good reason why SLR and professional camera use larger sensors. As yet I have not told the whole story ...
It's time I fessed up and told the whole story. The commonly given advice, is that if you care about image quality in general, and low image noise under poor lighting conditions in particular, then buy a camera with a large sensor, such as 4/3, APS, or even full-frame. That advice is correct.
However, it is also correct that the amount of light falling on the sensor is set by the physical size of the lens (aperture area), not by the sensor size, so how can these two apparently contradictory facts be reconciled?
A hypothetical example is the easiest way to explain. Consider a camera such as the Canon G11, with a smallish sensor, and a physically small lens. A previous posting showed just how small the absolute aperture actually is on a G11, from 2.2 to 6.7mm. Therefore we immediately know that the low light performance of this camera won't be good, because the absolute aperture of the compact lens is too small to collect much light, irrespective of the size of the sensor. Without altering the zoom range of the camera, the only way to improve matters and get more light on the sensor is to increase the aperture diameter of the lens. However, there are two ways to do this.
Method (1) is to fit a 'faster" lens, with lower f-number, and therefore larger aperture diameter. The G11 has an F2.8-4.5 lens, and it would certainly be possible in principle for Canon to fit this camera instead with an F1.4-2.2 lens. Yep, that would double the aperture diameter, and gather 4 times as much light. However, if we want even more light, and therefore an even larger aperture, we have a problem, because it becomes very difficult and expensive in practice to build lenses with an f-number less than around F1.4. What can be done? How can we increase the absolute aperture still further, without the need for impractically small f-numbers?
The solution, method (2), is to scale up the absolute aperture and the focal length in unison, leaving the f-number unchanged. Whoa, bingo, that's a great idea, because we can now increase the all-important aperture diameter almost without limit, without the need for impractically small f-numbers, but there is a pesky problem, because the increased focal length results in a reduced field of view. Fortunately the FOV can be maintained by scaling up the sensor, indeed, for this reason the sensor MUST be scaled up whether we want to or not!
Arguably then, the greatest advantage of a large sensor is that it allows the use of large aperture lenses without the need for impractically small f-numbers, which is why high-quality cameras, with large lenses to gather lots of light, will (must) always use a large sensor.
It is worth understanding that the FUNDAMENTAL requirement for gathering lots of light is a large aperture lens, and as a CONSEQUENCE of this, a large area sensor must be employed, if impractically small f-numbers are to be avoided. The converse is not true.
To summarize: (low image noise) needs (lots of light on sensor) needs (large lens) needs (large sensor, to avoid impratically small f-numer).
I realize that for many this will be a new and foreign way of looking at things, but in reality it is simple, factually correct, and very empowering. I also know that myths and old ways of looking at things die hard ....
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The problem with your argument is that you're assuming FOV is held constant for a lens. If the lens projects a large enough image circle to cover both sensors, then the FOV will not be constant, and the larger sensor will collect more light.
There is no problem with my argument. I think you objection was covered in posting#13. If not, get back to me.
Your equation also leaves out one rather important variable: exposure time. If two sensors used different lenses that had the same aperture area for the same FOV, that would imply that the larger sensor was using a longer lens at a smaller f/stop. In that case, the larger sensor would be using a longer exposure time, so it would still collect more light.
I have deliberately left exposure time out of the equation. It goes without saying that more photons can be collected with a longer exposure time. Any meaningful lowlight/image noise comparison between two cameras must obviously be made with the same exposure time, otherwise the cameara with the longer exposure has a grossly unfair advantage.
The larger sensor doesn't just 'permit' a larger lens, it requires a larger lens.
I'm not sure what you mean by "requires". It is certainly possible to use a small aperture lens with a large sensor. If you are saying that a larger sensor requires a larger lens to obtain any significant benefit, then I agree, that is precisely what I have been saying all along ....
It's not like you could stick a 4/3 sensor behind the G11 lens, the image circle is far too small.
The image circle is not the issue, again, see posting #13.
Sensor size and aperture area are linked. So what you say about aperture area is technically correct, but amounts to semantic quibbling that is essentially meaningless regarding the relationship between sensor sizes and image quality.
You would have to be more precise before I could comment. However, my later posting #26 may make my postition clearer, possibly we might even end up agreeing
Col
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Hi Suede,
I doubt you and I will ever disagree on a matter of theory or physics, or if we do it would quickly be resolved - that's the beauty of science. Any disagreement will likely be over matters of preference, such as do you prefer red or blue.
The physics of it is correct, but it is a very confusing way to try to explain it (as photographers are mostly F/no "thinking").
I don't believe the way I have explained things is inherently confusing, especially since I hopefully wrapped things up a bit better in posting#26. However, I agree entirely that most photographers are "f-number" thinking, and I believe that is a large part of the reason why so many find my way of explaining things foreign and maybe even confusing. It's not as if anything I have said is difficult to understand, and I honestly believe that someone learning photography for the first time would would find all I have said extremely easy to understand, and would regard the old way of looking at things as confusing and misleading, which in my opinion it is.
I could write a good deal about about both the usefulness, and drawbacks, of talking about everything in terms of f-numbers. Back in the good-old-days of film photography, most amateur photographic enthusiasts used the same 35mm film format. That made life very easy, because when one person talked about a 50mm F1.8 lens, everyone knew what that meant in terms of its absolute aperture, depth of field and FOV. The advent of digital photography, with everyone using cameras with different sensor sizes, has completely changed the game, but unfortunately the photographic community has not (for the most part) changed their way of looking at things. Confusion abounds, and much of that confusion is because people have clung excessively to thinking about everything in terms of f-numbers, which served them so well in the past.
But I'm very much a "prime" person, I rarely find uses for superzooms or even anything above the normal 3x zoom lenses. Larger sensors in compacts with smaller zoom ratios would fit me perfectly - but I'm aware that those products may be hard to sell in quantities enough to be lucrative to the maker.
We all have different needs and preferences. I agree that it makes sense to put larger sensors in compact cameras if the lens size can be kept compact, while still maintaining a decent aperture area, by either using primes, or a limited zoom range.
I think the S90 is a brilliant camera, not so much for what it is, but for what it shows could be built. I don't need my camera to be quite as small and light as the S90, so for me, a "scaled up" S90, where the sensor and lens were both scaled up such that the total camera size was more like a G11, would be a very interesting proposition. Maybe for you, too.
Cheers, Col
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Very theoretical discussion. Personally I have been surprized how sensors have been improved when looking at images from the g11.
There is a risk that discussing such things theoretically one does oversee small things and reality is totally different.
For example the S90 faster lens f2.0 which should lead to better images in low light since one could use either lower ISO or a faster shutter time to avoid shake. But then it seems the g11 with a little more mass and a larger grip is steadier to hold so you would hold the g11 as steady at 1/15 where you would need 1/30 for the S90.
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Very theoretical discussion. Personally I have been surprized how sensors have been improved when looking at images from the g11.
There is a risk that discussing such things theoretically one does oversee small things and reality is totally different.
For example the S90 faster lens f2.0 which should lead to better images in low light since one could use either lower ISO or a faster shutter time to avoid shake. But then it seems the g11 with a little more mass and a larger grip is steadier to hold so you would hold the g11 as steady at 1/15 where you would need 1/30 for the S90.
And more, for the S90, the antishake seems to be not as good as the one in the G10 !
And the lens is not as sharp, especially for edges !
And because there is a lot of barrel distorsion, the firmware corrects for, but you loose a lot of pixels.
So comparing G11 and S90 is comparing oranges and apples.
Have a Nice Day.
Thierry
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And more, for the S90, the antishake seems to be not as good as the one in the G10 !
And the lens is not as sharp, especially for edges !
And because there is a lot of barrel distorsion, the firmware corrects for, but you loose a lot of pixels.
So comparing G11 and S90 is comparing oranges and apples.
Have a Nice Day.
Thierry
Of course, the firmware doesn't correct the distortion if you shoot RAW, and on many subjects the distortion isn't significant enough to need correction.
I also believe if comparing actual prints from the two cameras most of the time to see any differences would require some serious pixel peeping.
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Of course, the firmware doesn't correct the distortion if you shoot RAW, and on many subjects the distortion isn't significant enough to need correction.
I also believe if comparing actual prints from the two cameras most of the time to see any differences would require some serious pixel peeping.
I woud expect so too.
IQ has been not the main factor for me to choose between S90 and g11 but more user interface.
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FWIW, I have been shooting with the S90 for the last two months, coming from the G10. The portability of the S90 is great, but IQ wise I must say that the DR seems to be even more limited than with the G10, and also the sharpness/clarity of the S90 is less impressive. I confirm "muddy fields and foliage" that has been reported elsewhere.
This is all from judging prints up to 11x14 - no scientific reasoning here.
I will continue to use the S90, but I will be more careful in making sure that the subject matter fits the camera, and not the other way around.
Mark
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A 100 pixel square was cropped from each image and the resulting grid is a 1 to 1 pixel ratio on the screen.
So taking a smaller portion of the G10 image than the G11 and S90 images (2/3 as much of the total image area) and enlarging it by a greater degree. How many times does it have to be said: one could make such a comparison between two different crops from the same file and the noise and other imperfections would look worse in the more enlarged display of a smaller portion of the image.
Could someone please do a test in which the cropped images compared cover the same part of the image, and so use the same fraction of the sensor area?
It would also be interesting to do "lens wide open" comparisons of various camera and lens combinations like G11, S90 and GF-1+14-45 so adjusting ISO speed to get equal shutter speed despite differences in lens speed. With compact camera options, "total camera speed" interests me far more than either "sensor speed" or "lens speed" in isolation. (I do not suggest comparing to the GF-1+20/1.7 as that would be a very one-sided contest against the 1/1.7" format cameras!)
That said, the noise gap looks more than the 50% increase in "used image area" can explain, so Sony and Canon have probably made some worthwhile progress with noise reduction.
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Hi BJL,
I use S90 and G10 and I've made a lot of comparisons.
What is evident, the G10 is by far better up to ISO200.
Above ISO800, S90 seems better than the G10.
But it's difficult to say ! Why ? Because the G10 High ISO raw files are color noise processed (very strongly for ISO1600).
Yes S90 High ISO colors are stronger, but sometimes you have "color cast" especially in yellow areas.
The G10 lens is very good with low distorsion and it's easy to remove chromatic aberrations.
With S90, from 28mm to more than 35mm equivalent, distorsion is high and in some cases you cannot completely suppress S90 chromatic aberrations.
So I will use both. S90 for everyday, and G10 when I carry more !
Thierry
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I confirm "muddy fields and foliage" that has been reported elsewhere.
Mark
How are you processing those files? I'm not really seeing this using LR beta 3 to process the files.
I think it goes without saying the s90 is not an idea landscape camera. It simply fills the need of making sure "The best camera is the one that's with you" is at least always better than my iPhone, and it's small enough to fill the bill of the family snapshot camera as well.
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How are you processing those files? I'm not really seeing this using LR beta 3 to process the files.
I think it goes without saying the s90 is not an idea landscape camera. It simply fills the need of making sure "The best camera is the one that's with you" is at least always better than my iPhone, and it's small enough to fill the bill of the family snapshot camera as well.
Oh absolutely. It's just that I have not been able to replicate the same level of separation with the S90 like I have with the G10 in for example this image:
(http://farm3.static.flickr.com/2529/3744409173_ae676fbb54_o.jpg).
Admittedly I have significantly processed this image in LR2, but was able to pull off enough detail to make it into a nice 11x14 print.
Using LR3 on the S90 as well - comparison-wise with the G10, grass/plains/foliage/trees etc just seem a bit more muddied.
Mark
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So taking a smaller portion of the G10 image than the G11 and S90 images (2/3 as much of the total image area) and enlarging it by a greater degree. How many times does it have to be said: one could make such a comparison between two different crops from the same file and the noise and other imperfections would look worse in the more enlarged display of a smaller portion of the image.
Could someone please do a test in which the cropped images compared cover the same part of the image, and so use the same fraction of the sensor area?
It would also be interesting to do "lens wide open" comparisons of various camera and lens combinations like G11, S90 and GF-1+14-45 so adjusting ISO speed to get equal shutter speed despite differences in lens speed. With compact camera options, "total camera speed" interests me far more than either "sensor speed" or "lens speed" in isolation. (I do not suggest comparing to the GF-1+20/1.7 as that would be a very one-sided contest against the 1/1.7" format cameras!)
That said, the noise gap looks more than the 50% increase in "used image area" can explain, so Sony and Canon have probably made some worthwhile progress with noise reduction.
I understand your point, and thought about doing this test as well, but it seemed sort of irrelevant. I don't think the G11 noise performance is so outstanding it merits upgrading over the G10, and this would most likely just reinforce that. So the feature set is what we have left, such as the articulating screen
To me these are just point and shoot cameras anyway ... I don't expect that much out of them. I'm never going to opt for an s90 or a G10/11 if I'm headed somewhere I believe a likely photo opportunity will present itself anyway.
I guess my bottom line is the s90 fits in my pocket, is easy to carry around. If want something "better" I won't bother with my G10, I'll grab the GF-1.
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I have both the G10 and the G11 and I have found that the IQ of the G11 is almost identical to that of the G10 at ISO 80/100. At higher ISO 200/800 the IQ of the G11 is far and away better I have found the appearance of the G11 images smoother and quite pleasing. I think any comparison of the G10 VS the S90 would hardly be fair as the quality of lens on the G10/G11 is probably better than that on the S90.
The bottom line is that if I really want a quality image file and quick focusing/composition I will have to cough up the money for a M9 to use with my M4's lenses.
All-in-all these little G series cameras... especially the G11 produce images of a quality level that only 5 years ago would be impossible to capture with cameras ten times the price.
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I guess my bottom line is the s90 fits in my pocket, is easy to carry around. If want something "better" I won't bother with my G10, I'll grab the GF-1.
Fair enough: my categories are "go absolutely everywhere" (like a S90 or something even smaller) followed by "go almost everywhere, in a jacket or back-pack pocket", where the GF-1 or E-P2 are very tempting. The G10, G11 and LX3 fall between chairs for me.
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With respect to improvements in sensor efficiency for compact cameras, I've noticed marginal improvement over the years... even with increasing megapixel counts. My Canon Powershot S40 and S50 produced very poor ISO 400 RAWs, which was characterised by significant loss of fine detail due to blotchy color noise. My G9 can produce pretty decent IS0 800 RAWs in good light only, but the S90/G11 sensor appears to do even better at retaining fine details at higher ISO, despite the noise which may be there. Some samples here:
http://www.dcresource.com/reviews/canon/po...90-review/using (http://www.dcresource.com/reviews/canon/powershot_s90-review/using)
I'm a little skeptical that these pocket cameras can achieve an IS0 3200 equivalent in RAW, without it being a "pushed" ISO, like ISO 3200 on the Canon 30D.
What then, is the real maximum sensitivity of a camera like the S90 or G11? Or, more importantly, the practical limit for maximizing the potential of ISO while shooting RAW?
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Was checking out the s90 and G11 the other day, and decided to do a quick noise test for fun.
All images taken on full manual (including focus). Processed in LR 3beta, with all noise reduction and sharpening turned off. The only thing I did was use use the white balance tool on the medium gray. Base exposure was IS0 100 for 1 second at f/8, aperture was kept constant and shutter speed varied as ISO was increased. A 100 pixel square was cropped from each image and the resulting grid is a 1 to 1 pixel ratio on the screen.
Working with the files, there is a definite and obvious quality difference between the GF1 and the smaller cameras, they were more like the 7d files. My personal opinion is that other than perhaps niche uses such as macro and underwater mentioned in another thread, the G11 doesn't have much to offer. The s90 delivers very similar quality, including similar noise performance and will actually fit in your shirt pocket. If the s90 isn't good enough, moving to the G11 won't get you all that much (as far as image quality). You are better off moving to the GF1, a camera which continues to impress me. Canon should consider a larger sensor version of a G11 for the G12. I'm going to take a s90 out for a day or two and shoot it alongside a 7d just for fun.
Handling of the G11 was odd at first ... the thumbwheel is smaller and a little awkward. I kept hitting the wrong buttons. Once I realized it protrudes further and you need to move it on the side rather than on the top it wasn't too bad. The articulating LCD is a nice feature, and the improved noise might make an upgrade worthwhile to some, but that's a pretty pricey upgrade to get about 1 more stop of noise performance and a swiveling LCD.
the grid is a little large, 1.5 mb ... I saved it at highest quality jpeg to minimize possible distortion of the noise from jpeg artifacts.
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H Wayne,
Thanks for starting this thread. Interesting discussion of various parameters..
I received a GF1 with the 1.7 pancake lens last week. I'm a working photographer (EOS 1 bodies) who has long wished for something more along the lines of the old Leica I carried in the late '60's that is digital and affordable. For personal work and projects, not my client stuff. I think the GF1 is almost there. I've been amazed at what this camera is capable of for street shooting. I sold my G10 yesterday. Today I mounted a Leica 35mm (equiv 70mm) f2 Summicron on the GF1 and went out and took a few shots. Worked great (although slower of course than the fast AF pancake f1.7 lens). Pic attached.
Tony Bonanno
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