# EOS Bodies - The ultimate duo & why



## Bombsight (Jun 9, 2011)

Whats your idea of the perfect combo of EOS bodies?

I like the 7D because I shoot a lot of sports in the water. The size of the 7D is much easier to handle compared to a 1 series in a water housing. 

Topside, I wish I had a 1 series sometimes ... but the 5DMKII does a superb job at everything that doesnt move fast.

Cant help but wonder how my relationship with my 5DMKII will be affected when the 5DMKII is available.

I just dont see myself parting ways with the 7D anytime soon .... especially when *new models* are rumored to have the same AF system.


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## ronderick (Jun 9, 2011)

IMHO, the best combo for EOS bodies would be a 7-series with 5-series body. 

I think the division of labor is pretty much straightforward here, with one handling the speed shots and the other handling the high MP shots.

Of course, you can also save a lot of room in your gear pack when carrying around standard-size bodies as opposed to the pro bodies...

PS: I always believe that there's a reason why Canon make these two models use the same battery  With the exception of the 1D/D's, I don't think there's a shared battery for two seperate lines of product.


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## prjkt (Jun 9, 2011)

ronderick said:


> IMHO, the best combo for EOS bodies would be a 7-series with 5-series body.
> 
> I think the division of labor is pretty much straightforward here, with one handling the speed shots and the other handling the high MP shots.
> 
> ...


60D also uses the same battery, and the 20D-50D used the same battery that the 300D and 5D (mark 1) used as well...


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## neuroanatomist (Jun 9, 2011)

ronderick said:


> IMHO, the best combo for EOS bodies would be a 7-series with 5-series body.



That's my opinion as well, and that's why I have that setup. Together, the combination runs a little less than the 'hybrid' 1DIV, and avoids the compromises of APS-H. If the only thing I shot was birds or sports, I'd be more tempted by the 1DIV, but as one who likes to shoot a little of everything, I appreciate the flexibility of a top APS-C camera with a high frame rate and very good AF performance, coupled with a FF body for portraits and landscapes, as well as excellent ISO performance for low-light use. 

A 1DIV would mean no ultrawide shots, and for the price of a 1D + 1Ds, I'd rather have the 7D + 5DII and a 500L (although I can see having a 1DIV and a 5DII - the weight/size aren't an issue for me, as I have battery grips on both bodies already).


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## ronderick (Jun 9, 2011)

prjkt said:


> ronderick said:
> 
> 
> > IMHO, the best combo for EOS bodies would be a 7-series with 5-series body.
> ...



Sorry, my mistake. I should have checked the batteries for those cameras.
Didn't realize that the older XXD series, 5D and other models use the BP-511 series battery.


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## Steve Todd (Jun 9, 2011)

I guess I have already let my feelings be known about this subject (see the "not many EOS-1s sold" posts). I have all three sensor size bodies (1D4, 7D, 5D and 5D2). I find that I carry my two 1D4s almost exclusively, one with either a 20-35 or 24-105 mounted on it and either a 70-300L or a 100-400L on the other body. If I only carry one body because of weight concerns while hiking for instance, then it's one of the 1D4s with my ole 28-300L attached. If I'm just out for a walk around town, it will be with the 24-105. On road trips where I have the luxury of having the car to carry the load, I'll sometimes take one of the 1D4 bodies along with my 5D2. However, when I look through my past images, I can see that even with the 5D2 and 20-35 attached, I tend to use the 35mm end more than the 20mm end of the scale. The same is true of when using the 1D4 bodies, I tend to use something more than the widest settings even for landscapes! The 7D, 5D and 5D2 bodies are great cameras, but for me and the types of shooting I do, the 1D4 is king. Eliminating the 1.3 crop sensor in the Flagship line doesn't make since to me! To me, it's all about personal choice and taste...use whatever works best for you, stay open minded and have FUN!


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## aldvan (Jun 9, 2011)

I added a 7D to my 5D MkII, since the 5D MkII can't fully support an extender for my 100-400 IS L. The idea was that the APS-C 1.6 factor would extend the maximum focal lenght to a virtual 640. On the paper the Mpx ratio (0.85) should outperform the FL factor (0.65) that I could obtain just by cropping. By the way, in the real world things go in a different way. The pixel quality of the 5D MkII is in an other league, and the best you can obtain by the 7D+100-400 is very similar to the same image cropped on the 5D MkII...
So, according to me the best duo is a pair of 5D MkII (or to have the patience to wait for a MkIII)...
I found the 7D an overestimated camera...


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## neuroanatomist (Jun 9, 2011)

aldvan said:


> By the way, in the real world things go in a different way. The pixel quality of the 5D MkII is in an other league, and the best you can obtain by the 7D+100-400 is very similar to the same image cropped on the 5D MkII...I found the 7D an overestimated camera...



Based on some previous empirical testing, comparing the same test scene shot with a 7D and 5DII, with the images from the latter cropped to the 1.6x FOV (resulting in an 8 MP image from the 5DII), the outcome boiled down to the 7D delivering images that were a bit sharper but a bit noisier than the 5DII. 

The other issues are AF - for fast moving subjects, even if the pixel-level IQ is similar, if the 5DII's AF system can't lock on and hold, the resulting images will be useless. Likewise, the faster shutter and shorter shutter lag and VF blackout duration on the 7D can help get shots the 5DII would miss. 

Thus, I think the 7D and 5DII complement each other very well. Yes, you can shoot action/wildlife with a 5DII, and portraits and landscapes with a 7D, but neither use is a strong point of those bodies. I'm a firm believer in using the right tool for the job at hand.


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## aldvan (Jun 9, 2011)

neuroanatomist said:


> Based on some previous empirical testing, comparing the same test scene shot with a 7D and 5DII, with the images from the latter cropped to the 1.6x FOV (resulting in an 8 MP image from the 5DII), the outcome boiled down to the 7D delivering images that were a bit sharper but a bit noisier than the 5DII.


That's exactly the point. The 7D has a lot more noise than the 5DII. I shoot just raw and processing by LR3 the 7D always needs NR, also at low ISO, where the 5DII, in good light condition is virtually noise free. 


neuroanatomist said:


> Thus, I think the 7D and 5DII complement each other very well. Yes, you can shoot action/wildlife with a 5DII, and portraits and landscapes with a 7D, but neither use is a strong point of those bodies. I'm a firm believer in using the right tool for the job at hand.


I agree with you. But, for my taste and my own style, a picture letting me to discover the finest detail, at every enlargement, is the right starting point. And since I always prefer to focusing only by the center point, the better AF of th e7D is quite useless. I have concluded that I'm a FF guy...


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## neuroanatomist (Jun 9, 2011)

aldvan said:


> ...a picture letting me to discover the finest detail, at every enlargement, is the right starting point.



But, if you have to crop your 5DII image to the framing of the 7D's sensor to achieve the desired FOV, the 7D would provide _more_ fine detail than the 5DII in that situation.

The 7D is noisier, but honestly, the difference is pretty much what the specifications would predict - the FF sensor receives 1.3 stops more light at a given aperture, and since noise is determined primarily by total light hitting the sensor, the ISO noise on the 5DII is ~1.3 stops less than on the 7D (e.g. ISO 200 on the 7D looks like ISO 500 on the 5DII). I confirmed that myself with yet another set of empirical tests.


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## WarStreet (Jun 9, 2011)

aldvan said:


> I added a 7D to my 5D MkII, since the 5D MkII can't fully support an extender for my 100-400 IS L. The idea was that the APS-C 1.6 factor would extend the maximum focal lenght to a virtual 640. On the paper the Mpx ratio (0.85) should outperform the FL factor (0.65) that I could obtain just by cropping.



This is not perfectly true. An important part of the resolving power comes from the lens, and one of the main advantages of the FF camera is the ability to use all the glass of the EF lenses, while the 7D will use a fraction of it. So in your examples you are diminishing the resolving power of the 5DII, but the 7D will still resolve more detail than the 5DII for the same FOV.

To find out the resolving power of the 5DII over the 7D you need to compare them with lenses attached. This is done by DXO. As an example, comparing these 2 cameras with the 100mm L @ 2.8 in the center of the frame, the 5DII gives 60 lp/mm and the 7D gives 49 lp/mm. This means that the 5DII resolve 1.22 times more, which is less than the 1.6 needed to get the same FOV of the 7D. 

I find it confusing to use the reciprocal ratios as in your examples, the lp/mm ratio of 0.82 (7D over 5DII) is greater than sensor height ratio of 0.62 (5DII over 7D)

The results varies by the performance of the lens/aperture/focal length/field position


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## aldvan (Jun 10, 2011)

I fear that we are, and I for one, getting lost in a sea of numbers. My superficial and naive idea was that the ratio of the total pixels of the 5DII and 7D (21/18) was lower than that of the respective FOV (1:1.6), allowing me to get a virtual 640 mm with a comparable quality. But, as a matter of fact, the real problem is that the area of ​​FF is 2.6 times higher than APS-C and that the single pixel has a size approximately double (5DII 24 400 pixels/mm to 7D 53,900 mm pixels/mm), and a phisically small pixel isn't any good for image quality. Beyond the numbers, all the tests I made ​​on the two cameras, and with the same microadjusted lenses (100-400 and 100 macro IS II), confirmed less details and more noise for the 7D in the real scene.


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## WarStreet (Jun 10, 2011)

I like numbers since they help you out, but as you say, the important thing is the end result, after all, FF gives other advantages in image quality instead of just resolution and noise, and when you are not cropping for the same FOV, there is no competition. 

When cropping , the noise 'increases'. One needs to compare the same print size equivalent, not 100% crop since this is what gives real life results on print or monitor. From neuroanatomist tests, In real life, the 7D will continue to perform the same as before, but the 5DII will be noiser than usual in this particular situation, but still better than the 7D. 

For detail, we need to see the same print size equivalent too, but with the downsampled example, you might not see all the advantages of the more detailed image when viewed on a monitor since both images _might_ be too detailed for the monitor. I think that the upsampled example is a better measurement for detail when viewed on monitor, but then there is the upsampling algorithm step involved in this comparison. The best is to compare it on a print. 

on the same theme, using a TC is better than cropping on an FF camera. Unfortunately, there is no data on DXO with TC. It would be interesting to see.


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## aldvan (Jun 10, 2011)

I fully agree with Warstreet on everything except on one point. You can appreciate the quality of detail on a monitor, it is sufficient to consider the two tests in a particular small enough for the monitor's pixels are sufficient to show all the pixels recorded by the sensor ...


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## neuroanatomist (Jun 10, 2011)

WarStreet said:


> on the same theme, using a TC is better than cropping on an FF camera.



In some ways, if you need the additional reach, the 7D is a perfect 1.6x teleconverter. It doesn't add any additional aberration, it doesn't slow down (or stop) autofocus, and it doesn't make the viewfinder any darker. Using a crop sensor with a higher pixel density will magnify the flaws in your lens, but with excellent lenses, that's a minor effect.

So, the bottom line is that if you have to crop your 5DII image to the 7D field of view, the 7D will produce better IQ. But, if you can move closer, or use a longer lens, the 5DII will trounce the 7D. 

The problem for me is that with small subjects like birds, achieving the FOV of a 400mm lens on the 7D, but using a FF body, would require spending $9K on a 600L (and I'd still need to crop a bit, or move a bit closer). Even at the 640mm FF equivalent, I find I often need to crop the 7D images a bit.


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## WarStreet (Jun 10, 2011)

neuroanatomist said:


> The problem for me is that with small subjects like birds, achieving the FOV of a 400mm lens on the 7D, but using a FF body, would require spending $9K on a 600L (and I'd still need to crop a bit, or move a bit closer). Even at the 640mm FF equivalent, I find I often need to crop the 7D images a bit.



A friend of mine like to take bird photos, and I told him more than once, that he has an expensive hobby 

I think using the 7D for bird photography is a great choice, as you say, it is the best TC, and great servo for the BIF too.


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## epsiloneri (Jun 10, 2011)

neuroanatomist said:


> In some ways, if you need the additional reach, the 7D is a perfect 1.6x teleconverter. It doesn't add any additional aberration, it doesn't slow down (or stop) autofocus, and it doesn't make the viewfinder any darker. Using a crop sensor with a higher pixel density will magnify the flaws in your lens, but with excellent lenses, that's a minor effect.



Just to be complete, there is one way in which a true TC might be better than higher pixel density, and that is when you aim for high dynamic range. With a TC you spread out the light over a larger area, and since the DR of a sensor scales with area, you should get higher DR with a TC + physically larger pixels (with the equivalent solid angle per pixel). This is in theory, I haven't tried it out in practice... do you know of any test where they compare e.g. a 5D2+1.4x TC combo to a straight 7D for various lenses? I'm curious to see if the drawbacks/advantages are as we expect or different. It would guide the choice of camera for various situations (as you point out, there are still ergonomic/AF advantages to 7D which could be more important than minor IQ differences). A specific application I have in mind is photographing a total solar eclipse, where the DR is important while AF is a non-issue, and FPS is not as important (but resolution could be).


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## neuroanatomist (Jun 11, 2011)

epsiloneri said:


> Just to be complete, there is one way in which a true TC might be better than higher pixel density, and that is when you aim for high dynamic range. With a TC you spread out the light over a larger area, and since the DR of a sensor scales with area, you should get higher DR with a TC + physically larger pixels (with the equivalent solid angle per pixel). This is in theory, I haven't tried it out in practice... do you know of any test where they compare e.g. a 5D2+1.4x TC combo to a straight 7D for various lenses?



I'm not sure about 'the DR of a sensor scales with area'. Looking at the DxOMark scores, both the 7D and the 5DII have a higher DR than the original 5D. Larger pixels have a higher full well capacity, but DR is not determined solely by full well capacity (dark noise and in-sensor processing also play major roles). 

I don't know of any test like this (TDP has sharpness and some distortion tests with/without extenders). But, when I did this test, I looked at DR (a backlit Stouffer step wedge with exposure adjusted so the lightest step was just below clipping). There was essentially no difference between the 7D and 5DII in terms of DR - both gave about 9 stops usable range. That's consistent with the DxOMark results, where the 5DII is only 0.2 stops better than the 7D (in their description, they mention that differences below 0.5 EV are not noticeable). So, I doubt using a TC would make a difference in DR.


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## Admin US West (Jun 11, 2011)

neuroanatomist said:


> epsiloneri said:
> 
> 
> > Just to be complete, there is one way in which a true TC might be better than higher pixel density, and that is when you aim for high dynamic range. With a TC you spread out the light over a larger area, and since the DR of a sensor scales with area, you should get higher DR with a TC + physically larger pixels (with the equivalent solid angle per pixel). This is in theory, I haven't tried it out in practice... do you know of any test where they compare e.g. a 5D2+1.4x TC combo to a straight 7D for various lenses?
> ...



Agreed. A TC will not improve DR, it just increases the apparent focal length of a lens. If that were true, the DR of a 10mm lens would be horrible, and for a 600mm lens, it would be extremely high.


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## epsiloneri (Jun 11, 2011)

neuroanatomist said:


> I'm not sure about 'the DR of a sensor scales with area'. Looking at the DxOMark scores, both the 7D and the 5DII have a higher DR than the original 5D. Larger pixels have a higher full well capacity, but DR is not determined solely by full well capacity (dark noise and in-sensor processing also play major roles).



Dark noise is important for long exposures (second or longer), for shorter exposures read-out noise is more important. Read-out noise depends on the electronics, but usually scales with the number of pixels - the read-out noise per pixel is usually similar for similar-generation cameras. E.g., 7D has 2.7 electrons/pix and 5D2 2.5 electrons/pix in read-out noise.

For well-exposed images the full-well capacity is far more important, however, since the Poisson noise will far out-weight the read-out noise. The full-well for a 7D pixel is 24800 electrons, while the 5D2 can accommodate 65700 electrons/pixel (i.e. close to the ratio of their pixel areas: (6.4/4.3)^2 = 2.22 while 65700/24800 = 2.65, so the 5D2 is actually doing a little bit better per area). For a full well, the Poisson noise contribution is thus sqrt(24800) = 157 photo-electrons for the 7D and 256 photo-electrons for the 5D2 (much higher than their read-out noise). 

In general, the signal-to-noise (S/N) per pixel is S/N = _P_ / sqrt(_P+R_^2), where _P_ is the number of photo-electrons and _R_ is the readout noise. So the 5D2 gives higher S/N per pixel than 7D. That's why the 5D2's pixels are thought to be "cleaner" or "higher quality" than the 7D pixels.



neuroanatomist said:


> I don't know of any test like this (TDP has sharpness and some distortion tests with/without extenders). But, when I did this test, I looked at DR (a backlit Stouffer step wedge with exposure adjusted so the lightest step was just below clipping).



It's a great service to the community you do by making those tests, I thank you for it. I don't think it is directly related to what I'm aiming at here. The test where you compared 5D2+135/2.0 to 7D+85/1.2 comes closer, since the 135/2.0 is almost like using a 85/1.2+TC1.4x (but not quite of course - there's a ~14% difference). What matters is the S/N per solid angle, and if the 5D2 provides a larger well for a solid angle, then it should provide higher DR. It should of course also take a longer exposure to fill that well, so exposure times would _not_ be equal.

Just to be clear, my question is: *for a given lens* (say 400/2.8 ) *and otherwise perfect conditions* (no motion blur, good manual focus, well-lit scene etc)* what combination would give the best S/N per solid angle for an optimally exposed image *(no high-light clipping): *a 7D, or a 5D2+TC1.4x?*

It sounds like this test should be easy to make, I'd be tempted to try it myself if you don't beat me to it.

(I pulled read-out noise and full well data from Clarkvision)



scalesusa said:


> A TC will not improve DR, it just increases the apparent focal length of a lens. If that were true, the DR of a 10mm lens would be horrible, and for a 600mm lens, it would be extremely high.



Funny that you give this example, because I believe it to be exactly true. The DR of a 10mm is horrible compared to a 600mm _if you look at the DR per solid angle_. Just think of it this way: The total number of photo-electrons of a scene in a well-exposed 10mm lens image should equal the total number of photo-electrons of a 600mm lens image. But the solid angle ("field of view") of the 600 mm lens image is much smaller than the 10 mm image - thus the number of photo-electrons per solid angle is much higher in the former case. Since DR in the high-photo-electrons limit is determined by the number of photo-electrons recorded, the DR is also higher. 

Or, think of producing the 10mm image by making a huge mosaic of 600mm images. Then it becomes obvious that the latter should provide a higher DR.


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## epsiloneri (Jun 11, 2011)

Sorry, I was a bit sloppy in the distinction between DR and S/N. They are closely related but not exactly the same. I trust it's still evident from my post what I mean.


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## WarStreet (Jun 11, 2011)

epsiloneri said:


> Sorry, I was a bit sloppy in the distinction between DR and S/N. They are closely related but not exactly the same. I trust it's still evident from my post what I mean.



Ironically, this was the ONLY thing I manage to understand. I like your contribution. Now, I only need to do some reading to decipher the above  Any suggestion ?


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## Heidrun (Jun 11, 2011)

My favoritt duo is difficult to say. I have to sat 2 bodies and 2 lenses.
First of all 1DS mk III with T&S 24 mm and 1D mk III with 24-70 mm


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## epsiloneri (Jun 11, 2011)

WarStreet said:


> Ironically, this was the ONLY thing I manage to understand. I like your contribution. Now, I only need to do some reading to decipher the above  Any suggestion ?



Thanks. Yes, it unfortunately got a bit technical, but what I essentially try to figure out is whether there can be an image quality advantage when it comes to dynamic range for a 5D2 + a 1.4x tele converter, as opposed to a 7D only. In many cases the 7D is better, e.g., frames per second, autofocus speed/tracking, no additional optics (no tele converter) etc, but when it comes to dynamic range (the ability to image both bright and dark features simultaneously) I argue there might be an advantage for the 5D2+TC1.4 combo.

If you are interested to learn how properties of a detector affect image quality properties, I suggest Clarkvision: http://www.clarkvision.com/articles/digital.sensor.performance.summary/ which has a good introductory summary.


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## neuroanatomist (Jun 11, 2011)

epsiloneri said:


> In many cases the 7D is better, e.g., frames per second, autofocus speed/tracking, no additional optics (no tele converter) etc, but when it comes to dynamic range (the ability to image both bright and dark features simultaneously) I argue there might be an advantage for the 5D2+TC1.4 combo.



If DxOMark is correct, there is no meaningful difference between DR of the 5DII and the 7D. Would you expect using a TC to improve the DR of the 5DII?


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## epsiloneri (Jun 11, 2011)

neuroanatomist said:


> If DxOMark is correct, there is no meaningful difference between DR of the 5DII and the 7D. Would you expect using a TC to improve the DR of the 5DII?



Yes, but again, _DR per solid angle_, obviously not per pixel. The DR per pixel only depends on the sensor properties, not the optics (irrespective of whether there is a TC or not).

Let me give a simple example to show you why. Imagine you are using your 5D2 to image a chess board from a large distance. Each chess square takes up exactly one pixel. Now let's say you use a TC 2x. Each square of the chess board now covers _four_ pixels. With four pixels you can collect four times as many photo-electrons for each square, meaning that the S/N (and essentially DR) improves by a factor of two per chess square, or _per solid angle_. If I have very a high contrast between black and white squares, I would get better signal in both by using the TC. (This of course assumes that the camera doesn't change position).

I cannot explain why DxOMark does not find a significant difference in DR between 5D2 and 7D. I didn't find a description of how they measure DR in detail, so I don't know what their numbers mean. It also stands in stark contrast to what is found on Clarkvision, which is much closer to my expectation. Perhaps DxOMark doesn't measure DR per pixel, but per sensor area or something. That would make sense. That a large 5D2 pixel would have the same DR as a small 7D pixel definitely does not make sense, so they must mean something different.


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## neuroanatomist (Jun 12, 2011)

epsiloneri said:


> Let me give a simple example to show you why. Imagine you are using your 5D2 to image a chess board from a large distance. Each chess square takes up exactly one pixel. Now let's say you use a TC 2x. Each square of the chess board now covers four pixels. With four pixels you can collect four times as many photo-electrons for each square, meaning that the S/N (and essentially DR) improves by a factor of two per chess square, or per solid angle.



I wonder if your simple example isn't mixing a metaphor (or in this case, mixing theory with practical reality). I understand the theory of 'adding pixels' with photon signal being additive while noise combines in quadrature, so the four pixels have twice the S/N over that spatial resolution. But doesn't that assume invariant illumination across the original pixel or the four 'added' pixels? In your example, the photons from that one chess square are spread over the area of four pixels (which is why the effective aperture with a 2x TC is 2 stops narrower). We're not creating a real superpixel, merely spreading out the light with diminished signal at each pixel, while each pixel still has the same read noise. So although the theory predicts double the S/N, that assumes 4 times as many photons input and twice the noise - and in your example, there aren't four times as many photons to go around. Or am I missing something?



epsiloneri said:


> I cannot explain why DxOMark does not find a significant difference in DR between 5D2 and 7D. I didn't find a description of how they measure DR in detail, so I don't know what their numbers mean. It also stands in stark contrast to what is found on Clarkvision, which is much closer to my expectation. Perhaps DxOMark doesn't measure DR per pixel, but per sensor area or something. That would make sense. That a large 5D2 pixel would have the same DR as a small 7D pixel definitely does not make sense, so they must mean something different.



I don't see any major discrepancy between DxOMark and Clarkvision, provided you carefully interpret Roger Clark's excellent and informative site. If you look at Figure 4, the 5DII has a 14.7-stop DR, and the 7D has a 13.2-stop DR - a 1.5-stop DR advantage for the 5DII. That's fine, but Figure 4 is based on Table 2, the sensor specifications - i.e., it's modeled/calculated data, not real, _empirical_ data. Some of my colleagues have a word for that sort of data, and while that's a bit harsh (even though I won't repeat it here), there's some truth to the idea. Skip down to Figure 5b, which is _measured_ DR for a few cameras. The 7D is not on the plot, but it's cousin the 50D is (the theoretical data in Figure 4 place it at ~13.4-stops of DR, close to the 7D and still a 1.3-stop advantage for the 5DII). From the empirical data, you can see that the 5DII's measured DR at ISO 100 is ~11.3-stops, and the 50D's measured DR is ~11 stops. The stated explanation for the differences between Figs 4 and 5b, "_The dynamic range is often limited by the A/D converter and other electronics in the system, illustrated by the measured data falling below the model at lower ISOs_," is not really satisfactory, since both cameras are falling below 12-bits, yet they both have 14-bit A/D converters. Looking at Figure 5b, you can appreciate at low ISOs, there's very little difference between the 5DII and the 50D in actual, tested DR.

Furthermore, it's worth noting that the measured DR's in Figure 5b are much more in line with DxOMark's data - which is consistent with the fact that DxO is empirically testing the cameras and lenses (although it would be nice if they provided some details about the testing procedures!).


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## aldvan (Jun 12, 2011)

neuroanatomist said:


> I wonder if your simple example isn't mixing a metaphor (or in this case, mixing theory with practical reality). I understand the theory of 'adding pixels' with photon signal being additive while noise combines in quadrature, so the four pixels have twice the S/N over that spatial resolution. But doesn't that assume invariant illumination across the original pixel or the four 'added' pixels? In your example, the photons from that one chess square are spread over the area of four pixels (which is why the effective aperture with a 2x TC is 2 stops narrower). We're not creating a real superpixel, merely spreading out the light with diminished signal at each pixel, while each pixel still has the same read noise. So although the theory predicts double the S/N, that assumes 4 times as many photons input and twice the noise - and in your example, there aren't four times as many photons to go around. Or am I missing something?



If I understand correctly the meaning of the debate - I'm not native English speakers, as you might guess - I believe that no one has yet introduced the basic concept of amount of information. In the example of the checkboard, getting sixteen pixels instead of four per square provides four times the information (I'm proportionally increasing the number of pixels in the example to be clearer). If at the four corners of a single checkboard square there are four grains of rice, getting sixteen pixels they will be visible, with four will see only a white spot. S/N and DR are important for image quality, but in my opinion the amount of information recorded comes before any other parameter. Forgive me for my poor English and if I'm off topic ...


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## epsiloneri (Jun 12, 2011)

neuroanatomist said:


> But doesn't that assume invariant illumination across the original pixel or the four 'added' pixels? In your example, the photons from that one chess square are spread over the area of four pixels (which is why the effective aperture with a 2x TC is 2 stops narrower). We're not creating a real superpixel, merely spreading out the light with diminished signal at each pixel, while each pixel still has the same read noise. So although the theory predicts double the S/N, that assumes 4 times as many photons input and twice the noise - and in your example, there aren't four times as many photons to go around. Or am I missing something?



You're right that the number of photons recorded per second does not change, so if you expose for a fixed time the S/N doesn't change (indeed gets worse because of the additional read-out noise). But since you are spreading the light from a chess square over four times as many pixels you can integrate four times longer and collect four times as many photons per chess square in one exposure. So I'm not talking about DR / solid angle / time; I'm talking about DR / solid angle for a good exposure (i.e. maximum exposure time without saturation), which in this case means exposing for 4 times longer with the TC.



neuroanatomist said:


> That's fine, but Figure 4 is based on Table 2, the sensor specifications - i.e., it's modeled/calculated data, not real, _empirical_ data.



Ok, so there are apparently some issues with the A/D converters at low ISO that fail to make use of the full potential (at least until ISO 2000 or so). That's good, because it means there is still room for improvement in future generation detectors! So not much help for the DR, but I expect there to still be a S/N advantage for 5D2 pixels and this seems confirmed by the DxO data, which show a factor of ~2 better S/N for the 5D2 pixels (3 dB at 18% of full well).

If we accept that the DR per pixel is the same for 7D and 5D2, then there would not be any DR advantage for 5D2+TC1.4x compared to 7D, because the 7D would still have more pixels per solid angle compared to the 5D2+TC1.4x combination (more precisely, ((6.39/1.4)/4.16)^2 = 20% as many, not really significant).

The S/N per solid angle on the other hand, should still be better in the 5D2+TC1.4x case, because 20% more pixels per solid angle is not enough to outweigh the factor of 2 S/N advantage.


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## epsiloneri (Jun 12, 2011)

aldvan said:


> If I understand correctly the meaning of the debate - I'm not native English speakers, as you might guess - I believe that no one has yet introduced the basic concept of amount of information. In the example of the checkboard, getting sixteen pixels instead of four per square provides four times the information (I'm proportionally increasing the number of pixels in the example to be clearer). If at the four corners of a single checkboard square there are four grains of rice, getting sixteen pixels they will be visible, with four will see only a white spot. S/N and DR are important for image quality, but in my opinion the amount of information recorded comes before any other parameter. Forgive me for my poor English and if I'm off topic ...



Many of us (including me) are not native English speakers, so no need to apologise. What you write is true but not relevant to the present discussion (as I interpret it). The question I am interested in is if there can be a dynamic range advantage in using a 5D2 with a 1.4x teleconverter as opposed to a 7D, since they both give angular scales per pixel that are roughly the same (the 5D2+TC1.4x pixels will only be 10% larger per linear angle). The resolution (pixels per angle) should thus be comparable in both cases, but the actual sensor surface covered is larger in the 5D2+1.4x case. Since the number of photo-electrons (electrons generated by incoming photons) a detector can hold is proportional to the area, I reasoned that the 5D2+TC1.4x combo should have a S/N advantage at the same resolution as 7D, and thereby in some ways produce a better image (but not in general, since a TC introduces additional optics that may distort the image).

What I wanted to show with the chess board example is why a TC improves the dynamic range / solid angle for a given detector. This "improved" DR is then compared to another detector of similar angular resolution, so no need to take resolution differences into account.

As it turns out, the 7D has _better_ dynamic range per sensor area than the 5D2 because of limitations in the A/D electronics that make them comparable on a per pixel level (where the 5D2 pixels are larger). So the 5D2+TC1.4x combo does not improve the DR over 7D (at least not until ISO~2000). The S/N per solid angle, however, _should_ improve (at the cost of 1.4^2 = 2 times longer exposures), which still makes this an interesting comparison (I think).


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## epsiloneri (Jun 13, 2011)

I tested the 7D vs 5D2+TC1.4x combination on the moon tonight (on a 400/2.8 lens). I exposed the best I could for the two settings, and focused with live view. Aperture was wide open (f/2.8 and f/4.0 with the TC). The moon was only 10 degrees above the horizon, so atmospheric turbulence was visible and limited the resolution somewhat, so this was not the best test. Here is the result anyway, with two 1-to-1 pixel scale crops lightly processed by DPP (default settings, i.e. sharpening set to 3), and a full moon more strongly processed and re-sampled (just for orientation). I find the 5D2+TC1.4x combination has a slight edge, but the difference is small and circumstances could play a role (e.g., instantaneous turbulence, precise focus). Looking carefully, the noise seems slightly better as well, but again the difference is small, and could just as well be due to camera sample variations.


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## aldvan (Jun 13, 2011)

To my eyes your example shows a clear superiority of the 5D on the 7D, no matter what the parameter makes it better. It is interesting that it was exactly Moon photography the reason to purchase a 7D. But after some tests I realized that I had not found the right solution and that's why I bought a Meade LX200 ...


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## jrista (Oct 19, 2012)

I do not have 5D II images to compare, however I believe that either you encountered some atmospheric distortion or camera shake blurring in the 7D image (something that is easy to do with the 7D, and not quite as easy to do with the 5D II, due to the much smaller pixel size). I've taken many moon images myself with the 7D, and it produces astonishing results. You do need to keep the camera very stable, and it is best if you shoot when the moon is high in the sky. You also need to keep it center of the lens for best results. On a per-pixel detail basis with the exact same lens, the 7D will always win vs. the 5D II, simply because it puts more pixels on subject than the 5D II can. Even vs. a lens with a 1.4x TC on the 5D II but not the 7D, the 7D should still have a slight advantage (about 5%), as on a pixel-size basis the 7D has a 45% (1.45x) reach advantage.

http://500px.com/photo/13321795 (B&W)
http://500px.com/photo/13321799 (Color)

http://500px.com/photo/13008253 (B&W)
http://500px.com/photo/12964733 (Color)

http://500px.com/photo/13008271 (B&W)
http://500px.com/photo/13008277 (Color)


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## epsiloneri (Oct 19, 2012)

Yes, I agree that the relatively softer image from 7D could very well be due to atmospheric distortion, since they were not simultaneous and due to the low altitude of the moon. This was in the summer, however, and from my location the moon did not rise much higher that night (I live on 59 deg northern latitude). If I find the time and a clear night I will repeat the experiment this winter with the moon much higher up (and a 5D3).


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## jrista (Oct 19, 2012)

epsiloneri said:


> Yes, I agree that the relatively softer image from 7D could very well be due to atmospheric distortion, since they were not simultaneous and due to the low altitude of the moon. This was in the summer, however, and from my location the moon did not rise much higher that night (I live on 59 deg northern latitude). If I find the time and a clear night I will repeat the experiment this winter with the moon much higher up (and a 5D3).



Thats a nice northerly latitude you live at there.  While it may not be the best for the moon, I bet you get some amazing auroras. I've never even seen an aurora in person myself...can't wait to get my butt up to Alaska sometime to photograph at night in the winter...preferably shortly after a partially earth-directed X-type Solar Flare. ;-)


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## RLPhoto (Oct 19, 2012)

The Ultimate Duo would be the 1Dx + 5D3. I just can't afford that kind of combo.


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## mrsfotografie (Oct 19, 2012)

For me: The 7D (sports/nature/AF speed) and 5DII (general photography) fits the bill perfectly. This combination definitely beats having a 5DIII (or 7D) only, and the 7D compensates for the 5DII shortcomings enough that I don't feel the need to upgrade my MkII.


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## bdunbar79 (Oct 19, 2012)

The ultimate I think is yet to come. Suppose we get a 7D Mark II with APS-C, then you will see a lot of 1DX owners happily purchasing the 7D2 as a second body. I do like the 1D4 though; the IQ is good enough that you still effectively get more reach than some of the older 1.6x crop factor cameras.

If you have the lenses, my choice was the 1DX/5D3 combo. It's expensive but I really enjoy the clean performance of these cameras where I shoot a lot: high ISO.

The most common best duo: Obviously the 5D Mark II/7D combo currently.


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## emag (Oct 19, 2012)

ronderick said:


> prjkt said:
> 
> 
> > ronderick said:
> ...



Canon used the BP-511 in a number of cameras. In my own case, I had at one time a G2, 300D, 40D and DV20 all using the same batteries! I still have and use the G2 and 40D, gave the 300D to my brother years ago and the DV20 is destined for trade in with CLS.


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## Chuck Alaimo (Oct 19, 2012)

First off, wow, love all the technical data, but, much of it is a bit over my head. I read and do my best to understand though. 

As to the perfect combo, as with everything it really depends on what your shooting. Right now I'm riding the 5d3/7d combo, but find that the 7d more often than not just sits to the sidelines. I am mostly shooting weddings, portraits and events though. Lots of lighting conditions, from well lit to fairly unlit - and more times than not in tight spaces. Even shooting concert from the soundboard I have found that the mk3 with 70-200 and no TC is fine (especially because on the mk3 I have much more room to play with ISO, which means I'm not as limited in DOF options, where with the 7d I'd want to stay as close to 2.8 as possible. But, given that I am usually shooting from right in front of the stage (i get soundboard shoots like 2-3 times a year), investing in a better way to cover that range just doesn't make sense (also, I'm not shooting sports all too often).

For my purposes, the best combo for me would actually be the 5d3/5d3 combo. But I'd also like to pick up a 16-35 this spring too. I have the 10-22, and I have been enjoying using the 7d-10-22 partnered with the 5d3-70-200. At a wedding that gives me close intimate shots, and Wider fun shots. But yeah, I am pushing the ISO on the 7d higher than I'd like in that situation. 

Other options are snagging a 5d2, or, possibly a 6d when we find out more about how that body works (I kind of like this option mostly because if I went this direction I could potentially keep the 7d, if i went mk3 I would have to sell the 7d (unless I can book more than I am expecting to book this fall). I have also been giving a good look at the 1d4 too.

All that said, my perfect body combo is probably not the same as everyones. It all depends on what you shoot. If I were offered a big contract to shoot sports this year, yeah, I'd be re-evaluating my setup big time. But as it stands for me, the advantages of FF outweigh 1.6 crop.


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## epsiloneri (Oct 19, 2012)

jrista said:


> While it may not be the best for the moon, I bet you get some amazing auroras.


If I lived in Canada that would be true, but in Europe you have to go even more north to see them regularly (although they show up here in Stockholm from time to time). I got a good display while visiting Yellowknife in Canada in 2009, however (50D, EF-S 10-22 f/3.5-4.5 USM @ 10mm/3.5, ISO 800, 15sec).


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## sandymandy (Oct 22, 2012)

1DX + 7D. Best APS-C and best FF. What else can i say. Personally i would go with 1DX and 5D mk3 since i dont need the APS-C crop factor for tele lenses. Hell, 1DX would satisfy all my needs but this thread was about 2 cameras  So...5D mk3 i would give to my fiance, ha!


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