Review of 7D by Darwin Wiggett

Started Nov 11, 2009 | Discussions
PeaceFrog Forum Pro • Posts: 12,185
Re: Review of 7D by Darwin Wiggett

Maybe it would be interesting to see a resolution test at several aperture settings. Of course you then have to worry about getting lenses that are up to the task which might be difficult.

Not every picture needs to be taken at the optimum settings for the camera and lens to be effective. If they did then cameras would come with only one aperture setting, one ISO setting…

Greg

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arindamdas Forum Member • Posts: 64
Re: Review of 7D by Darwin Wiggett

I agree.

Even if you have a f/2.8 lens, you will probably want to stop it down by 1 to achieve a bit more sharpness. This sets the lower bound (say f/4). Now, if you start seeing diffraction effects early, say at f/8, this sets the upper bound (I am under no pretense that these bounds have to be respected). The more megapixels that is crammed into a small format sensor, ultimately that's going to squeeze the optimal aperture range.

PeaceFrog wrote:

Maybe it would be interesting to see a resolution test at several aperture settings. Of course you then have to worry about getting lenses that are up to the task which might be difficult.

Not every picture needs to be taken at the optimum settings for the camera and lens to be effective. If they did then cameras would come with only one aperture setting, one ISO setting…

Greg

PeaceFrog Forum Pro • Posts: 12,185
Re: alundeb is essentially correct

Maybe you guys should do a little test to see which one does a better job (rebel XTi or EOS 7D). It would be interesting to see.

Greg

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PeaceFrog Forum Pro • Posts: 12,185
Re: Review of 7D by Darwin Wiggett

The more megapixels that is crammed into a small format sensor, ultimately that's going to squeeze the optimal aperture range.

While that may very well be true I wonder if a shot that is at a less than optimal setting on a 7D (stopped down for DOF) would be better or worse than an shot from a XTi with optimal settings. It would be an interesting test I think.

Greg

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tko Forum Pro • Posts: 12,823
hard to believe

First of all, DRP's own tests show's the 7d to have more resolution than either the 50d or D300s - look at the comparision pages, 1st two.

Second of all, my own resolution test shots show the 7d to be better than the 50d which is in turn better than the 40d. All my lenses look like they just got sharper! And that's JPEG or RAW, I don't care, and wide open.

On the other hand, the guy seems smart, unbiased, and he tried to like the camera, even trying 3 bodies. Kind of hard to understand why most of the sites show an advantage to the 7d when he doesn't. It's a complete mystery.

arindamdas Forum Member • Posts: 64
Re: alundeb is essentially correct

I cant help with this one

have an xsi (for general travel use), 40D (for wildlife and sports) and an FX from the dark side (for portraits and landscapes).

PeaceFrog wrote:

Maybe you guys should do a little test to see which one does a better job (rebel XTi or EOS 7D). It would be interesting to see.

Greg

The Davinator
The Davinator Forum Pro • Posts: 22,201
Re: hard to believe

tko wrote:

It's a complete mystery.

Diffraction, no understanding of capture sharpening.

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Greg Pavlov Senior Member • Posts: 1,888
Re: alundeb is essentially correct

One set of data that could give folks some idea of the relationship betw sensor density and IQ at higher f-stops is lens test data with different DSLR models. DPR's just-released tests of Canon's new 100mm macro is one example. Others are on PhotoZone, which has tested a good number of Canon lenses with 2 or more DSLRs. Overall, the resolution-f-stop curves for most lenses appear to be independent of sensor density. One exception appears to be PhtoZone's tests of the 17-55 f/2.8.

PeaceFrog wrote:

Maybe you guys should do a little test to see which one does a better job (rebel XTi or EOS 7D). It would be interesting to see.

Greg

Julio Veteran Member • Posts: 4,886
Good try by Darwin, but no cigar

I actually don't even care to speculate how and why he screwed up with his comparisons of manually-focused best IQ. It could be just about anything others above have mentioned.

Personally I trust those whose livelihood depends on doing these types of test properly--like DPReview, for example--than a photographer with a blog who indulges his measurbating fantasies. Some of those photographers actually take great photos...doesn't mean they have a clue about absolute and extinction resolution measurements (pages 28, 29 of the DPR review) or how to acurately measure color response (page 18 here.)

Just another photographer with a bellybutton...move along, nothing to see there.
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arindamdas Forum Member • Posts: 64
Re: alundeb is essentially correct

hey, thanks Clint

been to Vancouver numerous times (Seattlite here), beautiful city!

Kevin Peters Senior Member • Posts: 1,326
Re: Review of 7D by Darwin Wiggett

TOO MANY PIXELS, such as in the 7D screw up IQ!

alundeb wrote:
What?

What other camera is there with that pixel density? The 7D has 50% more pixels per area than the Xsi and D300, and more than double the pixel density of the 1ds3.

Using f/8 with 1.6 crop isn't a senosr specific problem.

Trading DOF against diffraction is a fundamental property of photography. There is no format that can provide less diffraction at a give DOF than another.

Greg Pavlov wrote:

alundeb wrote:

Raw converter (green channel differences not correctly handled), and aperture, sadly as usual with all reviews of 7D sharpness.

Come on, f8 to f16 on a 18 MP crop.

The 7D is not the only high-density sensor camera with photos in this review. And if the 7D is truly diffraction-limited by f8, that is a problem (I suspect, tho, that diffraction is not the issue here).

c82 New Member • Posts: 9
Re: Shoot landscapes at f/7.1

Could photographers needing greater sharpness and also more depth of field use the 7D's 10mp Raw mode? Sure you don't get an 18mp image, but in theory it shouldn't suffer as much from the effects of diffraction, right?

I suppose downsizing in PP could have the same effect.

David Hull
David Hull Veteran Member • Posts: 6,349
Re: Dear alundeb......

David_C wrote:

You have some interesting points, but I found it interresting that the reviewer tried 3 different 7D's.

He tried 3 7D's which all were working properly and all of which gave him the same result. This was not because the 7D was defective, it was because the photographer doing the review, didn't understand what he was doing. I think that the people here who DO understand this, have tried to make it pretty clear.

One would think that the fact that he tried three cameras all of which gave him bad results might make him examine his technique -- but apperently not.

So I look forward to your in-death review of the 7D, alundeb, to show us how to properly test a camera and write a review.

Dave

alundeb wrote:

Raw converter (green channel differences not correctly handled), and aperture, sadly as usual with all reviews of 7D sharpness.

Come on, f8 to f16 on a 18 MP crop.

Did they say f16? On a crop? The airy disc is two pixels wide.

If a reviewer doesn't know that you must use 1 1/3 stop wider aperture on a 1.6 crop sensor to get the SAME DOF AND DIFFRACTION, they are far off.

They don't have a clue what they're doing.

Our only hope for a correct measurement of 7D resolution is photozone, they use apertue f/4.

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doable Regular Member • Posts: 122
Re: sharpening

Even with my 30D I use 5 sharpening with ISO 100 & 200 shots for batch conversions. As other more knowledgeable say, even with more defraction in higher mp cameras you still get more detail from the higher resolution, therefore better photos. You need sharpening, 3 is too soft from default standard picture style, even on the 30D.
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Daniel Clune
Daniel Clune Veteran Member • Posts: 3,453
MY 7D Xsi comparison pics

I saw this test and since i have both a 7D and a rebel Xsi i did a quick test of a lens chart i printed a few years ago for testing lenses. Its a 13 by 19 inch print done on my old canon S9000 printer..

Shots taken on tripod mirror lockup 2 sec self timer focus done manually in live veiw 10X magnify. I shot both jpg and raw i used the raw for this test, processed in DPP no sharping and no noise reduction. I uped the exposure about .67 in DPP since they were a little under exposed since the target is mostly white. I could have used exposrue comp but did this quickly. I doubt it would have any effect and sharpness. The first 3 are 7D first at F4 then F8 then F13 next three Xsi same F stops.
Full size pics here http://www.pbase.com/dc9mm/7dcompare450d
here is a crop i took from the center from the F4 shots.

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jameslj Regular Member • Posts: 125
Re: MY 7D Xsi comparison pics

Looks like a fair test. To my eyes, the XSI ones look a bit tighter. I don't see much to worry about in the 7D ones, though.

I really don't know about evaluating photo IQ based on essentially unprocessed 100% views, though. Fun as it is!

arindamdas Forum Member • Posts: 64
Re: MY 7D Xsi comparison pics

based on the full size images, I don't see too much of a difference between the xsi and the 7D. are you seeing anything different?

did both the cameras underexpose?

Daniel Clune wrote:

I saw this test and since i have both a 7D and a rebel Xsi i did a quick test of a lens chart i printed a few years ago for testing lenses. Its a 13 by 19 inch print done on my old canon S9000 printer..

Shots taken on tripod mirror lockup 2 sec self timer focus done manually in live veiw 10X magnify. I shot both jpg and raw i used the raw for this test, processed in DPP no sharping and no noise reduction. I uped the exposure about .67 in DPP since they were a little under exposed since the target is mostly white. I could have used exposrue comp but did this quickly. I doubt it would have any effect and sharpness. The first 3 are 7D first at F4 then F8 then F13 next three Xsi same F stops.
Full size pics here http://www.pbase.com/dc9mm/7dcompare450d
here is a crop i took from the center from the F4 shots.

Gtam Forum Member • Posts: 66
Re: Focus Issue ?

The 100% crops on the yellow tree and the hay bale with the are obviously out of focus and the higher resolution of 18MP is unforgiving with OOF zones.

From the framing of the shots its seems that focus was neither made on the trees in the foreground nor at the rear of the hay bale. In all logic, the shooter must have aimed at the front of the bale and the composition of the picture with the yellow trees suggests that she was not aiming at the trees.

Or, possibly, the tester's 7D copy might have a focus issue and needs to be returned to a qualified repair shop, as the mountain top and the ears of corn do not seem perfectly in focus either.

It would be insteresting in this thread to see 100% crops from pictures of yellow leaves, hay bales and ears of corn in the same conditions, but when in focus. Less critical with the upper ear of corn

David Franklin Senior Member • Posts: 1,145
Re: alundeb is essentially correct

Clint,

My point was perhaps not complete, because I thought that people would fill in the blanks I left out of my post, for brevity sake. The most important factor for deciding sensor diffraction is "pixel"-sensor size, not just sensor size, although, for comparison, there are no current "full frame" sensors with anything near the pixel size of a 7D, or even a T1I. That was why I made that comparison. Because the pixel size (and cosequent sensor density) of the 7D is smaller than that of any other 1.6X sensor camera, diffraction will set in earlier. And, although the depth of field stasis I discussed will not apply as in 1.6X compared to full frame, the aperures at which diffraction becomes a factor will apply as to sharpness. If you want to use an 18 MP sensor for reasons of DPI and a small aperture for your lens, you will need to use a bigger format sensor in order to avoid or lesson diffraction, thereby again, bringing about the depth of field stasis I mentioned in my last post. But yes, comparing just one more dense to one less dense APS-C sensor, the less dense one will allow a slightly smaller aperture before diffraction sets in. This can be somewhat mitigated by better raw conversion, better sharpening, and, surelly, downward image sizing to the pixel count of the less dense sensor if the greater DPI is not required.

Regards,
David
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Daniel Clune
Daniel Clune Veteran Member • Posts: 3,453
Re: MY 7D Xsi comparison pics

Yes both cameras under exposed BUT so did every other camera i have used the test chart on (D30, 10D, XT, 1DMKII, 1DSMKII, and now Xsi and 7D) Its mostly white so all cameras will under expose on it. I just mentioned it as i forgot to use exposure comp when taking the pics. I was in aperture priority mode.

To me it looks like the Xsi has a weaker anti alias filter than 7D. But you can always sharpen up the 7D. See
'

arindamdas wrote:

based on the full size images, I don't see too much of a difference between the xsi and the 7D. are you seeing anything different?

did both the cameras underexpose?

Daniel Clune wrote:

I saw this test and since i have both a 7D and a rebel Xsi i did a quick test of a lens chart i printed a few years ago for testing lenses. Its a 13 by 19 inch print done on my old canon S9000 printer..

Shots taken on tripod mirror lockup 2 sec self timer focus done manually in live veiw 10X magnify. I shot both jpg and raw i used the raw for this test, processed in DPP no sharping and no noise reduction. I uped the exposure about .67 in DPP since they were a little under exposed since the target is mostly white. I could have used exposrue comp but did this quickly. I doubt it would have any effect and sharpness. The first 3 are 7D first at F4 then F8 then F13 next three Xsi same F stops.
Full size pics here http://www.pbase.com/dc9mm/7dcompare450d
here is a crop i took from the center from the F4 shots.

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