1DS3 vs 5D CoC shootout in MFDB forum

[Anthony R]

Thanks for this thread. It allowed me to update my ignore user list.

[Mark D Segal]

Hey! This was incidental testing on my trip to Australia's highest waterfall. There's a limit to the amount of testing I'm prepared to do.

It seems fairly clear, so far, if I buy the 24mp Sony A900 I'm going to have to hone my skills at focus bracketing if I want to improve on the DoF and resolution that the 5D can provide at F16.
[a href=\"index.php?act=findpost&pid=207072\"][{POST_SNAPBACK}][/a]

Ray, take it easy - don't fall off the mountainside. Sounds like a nice place. To keep in mind if I ever get to that part of the world.

Ya - in those conditions I agree - limits to testing - but twirling the aperture ring a few notches ain't a big-time stress factor, even in the upper atmosphere. Anyhow, whatever, however. As you can and want.

I don't believe the sensor is the determinative factor for what you want from good focusing technique - for any quality DSLR. And I remain to be convinced that what you see from the 40D is necessarily a reliable guide to what you will get from a Sony A900. That remains to be seen.

[BJL]

I used the 100-400 at 400mm, the TS-E 90/2.8, the 50/1.4 and the Sigma 15-30, all at F16, and other apertures, and all at the same focal length and from the same position.
... You can't get more resolution than the 5D at F16, no matter how many pixels ...
[a href=\"index.php?act=findpost&pid=206977\"][{POST_SNAPBACK}][/a]

Are you saying that none of those lenses shows any improvement in resolution as one opens up from f/16, even with the 40D? If so, I suggest that you need to seriously reconsider your choice of lenses! There is good evidence that in at least one other SLR system, most or all lenses have higher resolution at their optimal apertures (between f/4 and f/8) than is allowed by diffraction alone at f/16.

[Mark D Segal]

Are you saying that none of those lenses shows any improvement in resolution as one opens up from f/16, even with the 40D? If so, I suggest that you need to seriously reconsider your choice of lenses! There is good evidence that in at least one other SLR system, most or all lenses have higher resolution at their optimal apertures (between f/4 and f/8) than is allowed by diffraction alone at f/16.
[a href=\"index.php?act=findpost&pid=207093\"][{POST_SNAPBACK}][/a]

Exactly. Back to ranges and limits again: what's the binding constraint: whether we're talking a 40D, a 5D, a 1Ds3, a D3, a D300 - the sensor is most unlikely to be the binding constraint, but f/16 probably is, and if so, these comparisons aren't saying much about either absolute or comparative resolution for these sensors.

[bjanes]

Exactly. Back to ranges and limits again: what's the binding constraint: whether we're talking a 40D, a 5D, a 1Ds3, a D3, a D300 - the sensor is most unlikely to be the binding constraint, but f/16 probably is, and if so, these comparisons aren't saying much about either absolute or comparative resolution for these sensors.
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Yes, if you go back to that Zeiss D200 plot I posted, the Nyquist of the camera is 82 lp/mm and maximal observed MTF50 was 71 lp/mm at f/4. At f/16 the ideal lens MTF50 is 48 lp/mm (for green light) and the observed MTF50 was 56 lp/mm. The MTF above the ideal is most likely due to sharpening, which has a marked effect on MTF50.

The link below is from my own test using the D200 and Imatest. The results are shown without sharpening (uncorrected) and with standardized sharpening (corrected). If you want to compare lenses or diffraction effects, it is best to disable sharpening. Generally speaking, the best you can do with a Bayer arrar camera is 75-80% of Nyquist. The best results with this lens were at f/5.6 and I suspect the results for Ray's Canon 50mm f/1.4 would be similar. You can look up the results with that lens and the EOS 350 on PhotoZone.

Bill

[a href=\"http://bjanes.smugmug.com/photos/53712086_UaE9x-O-1.gif]http://bjanes.smugmug.com/photos/53712086_UaE9x-O-1.gif[/url]

[ejmartin]

Yes, if you go back to that Zeiss D200 plot I posted, the Nyquist of the camera is 82 lp/mm and maximal observed MTF50 was 71 lp/mm at f/4. At f/16 the ideal lens MTF50 is 48 lp/mm (for green light) and the observed MTF50 was 56 lp/mm. The MTF above the ideal is most likely due to sharpening, which has a marked effect on MTF50.

The link below is from my own test using the D200 and Imatest. The results are shown without sharpening (uncorrected) and with standardized sharpening (corrected). If you want to compare lenses or diffraction effects, it is best to disable sharpening. Generally speaking, the best you can do with a Bayer arrar camera is 75-80% of Nyquist. The best results with this lens were at f/5.6 and I suspect the results for Ray's Canon 50mm f/1.4 would be similar. You can look up the results with that lens and the EOS 350 on PhotoZone.

Bill

http://bjanes.smugmug.com/photos/53712086_UaE9x-O-1.gif
[a href=\"index.php?act=findpost&pid=207114\"][{POST_SNAPBACK}][/a]

OK, if one posits that diffraction is setting in somewhere between f8 and f11, shouldn't we attribute the downslope there and beyond to diffraction effects, or is there more going on?  

If it's just diffraction, then the uncorrected MTF50 drops by about 1/3 between f11 and f22, while the aperture is dropping by 1/2.   The effect of stopping down is to change the size of the Airy disk relative to Nyquist, so if diffraction limitation were a hard cutoff one should see MTF50 drop in proportion to f number rather than more slowly as it does.  

Assuming that the limiting effect is diffraction and not any optical aberrations of the lens, if the effect of diffraction on MTF50/Nyquist is dependent only on pixel spacing/Airy disk size, and I don't see offhand why it shouldn't be (the question is how big is the diffraction blur on the scale of the sampling array), then stopping down by two stops should have the same effect as halving the pixel size -- both change the ratio of the pixel spacing to the Airy disk size by the same amount.

Thus halving the pixel size at f11 should have the same effect on MTF50 relative to Nyquist as keeping the same pixel size and doubling f number, and as we have seen the MTF50 goes down by less than a factor of two.  This says to me that increasing pixel density even beyond the point where diffraction limitation sets in, will result in a net gain of resolution (as I and others were arguing before), at least for a while.  Less than double the resolution, for sure, but more than nothing (the simple linearized model I am suggesting would say that one gets 4/3 the resolving power).  But maybe the model is too naive?

[bjanes]

OK, if one posits that diffraction is setting in somewhere between f8 and f11, shouldn't we attribute the downslope there and beyond to diffraction effects, or is there more going on? 

But maybe the model is too naive?
[a href=\"index.php?act=findpost&pid=207128\"][{POST_SNAPBACK}][/a]

Emil,

I don't know if the model is linear or what, but am merely reporting observed results. Since you are the physicist, I would accept your interpretation. In any event, if you stop down to f/16 with the tested camera and lens, you lose MTF. If you look at the results on PhotoZone, you will see that this is generally the case with similar pixel spacings.

Bill

[joofa]

and so the sensor MTF will be a steeply decreasing function of spatial frequency starting from say 1/3 to 1/2 Nyquist, and which vanishes around Nyquist. 

The power spectrum of natural images decreases in proportion to more or less the inverse of the square of the frequency. The highest value, is of course, the DC entry.

If the power spectrum did not fall we could kiss compression schemes such as wavelet, mpeg, h.264, etc., good bye.

[Nick Rains]

I've concentrated on the rocks in sunlight. 100% crops still show no greater detail from the 40D.

[attachment=7401:attachment]  [attachment=7402:attachment]
[a href=\"index.php?act=findpost&pid=207022\"][{POST_SNAPBACK}][/a]

Just came across this thread...

Ray, in these shots of the rock face the 40D looks clearly sharper to me. ejmartin's analysis confirms this. Do they not look different to you?

[ejmartin]

The power spectrum of natural images decreases in proportion to more or less the inverse of the square of the frequency. The highest value, is of course, the DC entry.

If the power spectrum did not fall we could kiss compression schemes such as wavelet, mpeg, h.264, etc., good bye.
[a href=\"index.php?act=findpost&pid=207141\"][{POST_SNAPBACK}][/a]

Yes, but I presume that Bill was shooting a test target, which have sharp edges or sinusoidal variation with spectral power out to high frequency.  A proper test target used in a proper test methodology should not in and of itself limit the MTF as a function of spatial frequency, otherwise the testing methodology is flawed.  Are you saying that Bill's measured MTF50 is inaccurate?

MTF simply tells you how much of the spectral power of the scene is transferred to the recording medium.  It is not a function of the spectral power distribution of any particular scene you wish to photograph (including a test chart), and doesn't care whether that power is large or small, it just says how much of that large or small power gets through.

[bjanes]

Yes, but I presume that Bill was shooting a test target, which have sharp edges or sinusoidal variation with spectral power out to high frequency.  A proper test target used in a proper test methodology should not in and of itself limit the MTF as a function of spatial frequency, otherwise the testing methodology is flawed.  Are you saying that Bill's measured MTF50 is inaccurate?

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Imatest uses a [a href=\"http://www.imatest.com/docs/sfr_instructions.html]Slanted Edge Target[/url], which is a standard ISO test method. It is not necessary to have variable frequency bars and the camera to target distance is not critical. If you have the point spread function of one transition, the remaining data can be calculated. Imatest is fairly idiot proof, and there could be some inaccuracy in my results, but the overall trends should be fairly accurate. The newer versions can also use a Siemens Star to calculate MTF along multiple axes.

Users of ImageJ can download a plugin to perform the calculation from that excellent freeware program. You can download some test images from the DPReview tests or I could upload a couple of images if someone is interested in the raw files.

ImageJ Plugin

Bill

[ejmartin]

Imatest uses a Slanted Edge Target, which is a standard ISO test method. It is not necessary to have variable frequency bars and the camera to target distance is not critical. If you have the point spread function of one transition, the remaining data can be calculated. Imatest is fairly idiot proof, and there could be some inaccuracy in my results, but the overall trends should be fairly accurate. The newer versions can also use a Siemens Star to calculate MTF along multiple axes.

Users of ImageJ can download a plugin to perform the calculation from that excellent freeware program. You can download some test images from the DPReview tests or I could upload a couple of images if someone is interested in the raw files.

ImageJ Plugin

Bill
[a href=\"index.php?act=findpost&pid=207153\"][{POST_SNAPBACK}][/a]

Cool!  ImageJ is one of my favorite analysis tools.

[Ray]

Are you saying that none of those lenses shows any improvement in resolution as one opens up from f/16, even with the 40D? If so, I suggest that you need to seriously reconsider your choice of lenses! There is good evidence that in at least one other SLR system, most or all lenses have higher resolution at their optimal apertures (between f/4 and f/8) than is allowed by diffraction alone at f/16.
[a href=\"index.php?act=findpost&pid=207093\"][{POST_SNAPBACK}][/a]

No. So far, I'm saying that at F16 I can see no worthwhile improvement, but that might be partly due to the inadequacy of my Dell Inspiron 710 laptop.

However, despite my using a laptop, a 100% crop represents a pretty large print.

[Mark D Segal]

No. So far, I'm saying that at F16 I can see no worthwhile improvement, but that might be partly due to the inadequacy of my Dell Inspiron 710 laptop.

However, despite my using a laptop, a 100% crop represents a pretty large print.
[a href=\"index.php?act=findpost&pid=207175\"][{POST_SNAPBACK}][/a]

Two reasons why you may not be seeing the improvement are (1) diffraction from the use of f/16 for the captures and (2) the resolution limit of your laptop screen. I often see detail in prints (Epson 3800) that don't show as well on my high-res laptop (LaCie 321 1600*1200, resolution 94 PPI - i.e. 1600/17 in. wide).

[Ray]

Just came across this thread...

Ray, in these shots of the rock face the 40D looks clearly sharper to me. ejmartin's analysis confirms this. Do they not look different to you?
[a href=\"index.php?act=findpost&pid=207145\"][{POST_SNAPBACK}][/a]

Nick,
Having looked more closely this morning, the 40D crop does appear slightly sharper and more 'integrated', especially in the upper left region.

However, what I'm looking for is more detail; some smidgen or speck that is clearly defined in the 40D shot but not in the 5D shot.

Accutance is something one can create to taste in accordance with intended print size. The 5D crop has been interpolated to more than double its size without further sharpening. It's not ready for print and because it's been interpolated it should, I believe, have more sharpening than the uninterpolated 40D shot, before printing.

From a practical point of view, what counts is the print on the wall after appropriate processing, and I can't test that in my present circumstances.

[Ray]

Ray, I'm still confused as to why you say that the 40D has no greater detail.  I downloaded your 100% crops and did a spatial frequency analysis.  Here is the Fourier transform of a 256x256 portion of the same area from each image:



Nyquist is out at the edge of the square, low frequencies are in the middle.  Black is no power, bright is lots of power.  What you see is that the 40D has much more power at high spatial frequencies, indicating more detail (and it's not just noise power, that is a soft grey background that goes all the way out to the edges; I'm talking about the extent of the bright blob above that background).  If the 40D were not resolving any more than the 5D, the extent of the bright disk would be the same for the two images.  This just reaffirms what my eyes are telling me, that the 40D is getting way more detail.
[a href=\"index.php?act=findpost&pid=207083\"][{POST_SNAPBACK}][/a]

Emil,
No greater detail that I consider significant, as far as I can judge on my laptop and bearing in mind that the upressed 5D crop has not been sharpened.

It looks as though the results might be more conclusive if I shoot newspapers. There's nothing more convincing than legible text.

[ejmartin]

It looks as though the results might be more conclusive if I shoot newspapers. There's nothing more convincing than legible text.
[a href=\"index.php?act=findpost&pid=207185\"][{POST_SNAPBACK}][/a]

Fresh currency notes are a good choice; crisp detail down to very fine scales.

[ejmartin]

I think I finally found what I was looking for.  DPReview's new lens tests do resolutions tests for the 70-200/2.8L on both the 5D and 40D out to f32:

http://www.dpreview.com/lensreviews/canon_...m_c16/page4.asp

A quick eyeball of the results shows that, for a decrease in pixel pitch by a factor of 1.45, the resolution in lp/mm improves at f5.6 by nearly the difference of their Nyquist frequencies; at f8 the 40D has about a 25% advantage, at f11 about a 20% advantage; then the difference narrows to about a 10% advantage for the 40D for all apertures f16 and narrower, all the way out to f32.  

So again, the improvement is not as great as the ratio of pixel pitches once diffraction sets in, there is a law of diminishing returns, but one still gets about a quarter of the change of Nyquist in terms of resolution improvement (FWIW -- probably not much -- my crude little model was predicting about 1/3 of the change in Nyquist) even at very narrow apertures.

[Ray]

Having looked at a few more tests at various apertures, it's clear the 26mp sensor provides a substantial improvement in detail at F8, as expected, compared with the upressed 5D crop at F8.

At F22, I have to admit that, even after applying a bit of additional sharpening to the interpolated 5D image, the 40D image looks better, slightly finer grained and perhaps even has a greater 3D effect, although I'm still doubtful if such subtleties would be noticed in a normal size print of, say, 22"x33".

A 100% crop of a 26mp image on this laptop represents a print size of about 5 feet by 3 1/2 feet.

Here's the F8 comparison, followed by the F22 comparison with the interpolated 5D crop sharpened 100% at pixel radius 0.8.

[attachment=7412:attachment]  [attachment=7413:attachment]

[Panopeeper]

I created a replicable, reliable test set with the 40D. The scenery is very exciting, see below (a moskito screen). I made a crop from the center of all full stop apertures of the EF-S 17-55mm f/2.8 at 55mm.

The top row contains the "compound" image (four identical pixels for the four pixels of a Bayer subarray), the bottom row shows it raw pixel for raw pixel; both in 5x magnification.

The threads of the screen are 4 pixels wide at the best resolution. At f/16, and particularly at f/22 one can see JPEG-like artifacts. They are not from JPEG, but from diffraction.