Trying out the 7D

[keith_cooper]

Canon have lent me a 7D to have a go with...

Very nice, but I don't really do DPR type reviews (I don't have the patience - and loads of sites do camera reviews) so I thought I'd write a few short articles/blogs about what the camera is like to use from the point of view of someone who's only regular DSLR experience is using a Canon 1Ds and 1Ds3.

Sure it's smaller and my ability to multiply numbers by 1.6 has improved, but it works very nicely and quality wise, I was quite impressed by what you can get out of 18MP on a chip that size (but no I don't want a 45MP FF one at the same quality)

Not doing any real sports/BIF stuff, the AF performance seems good, but there are an awful lot of variations in settings, that I fear many will not take the time to explore/experiment with before saying that it doesn't focus ;-)

One quick test showed that unlike the 1Ds3 there was no obvious advantage in avoiding the fractional stop ISO settings
7D fractional stop ISO performance

I'm not sure how long I've got the camera for, but I'm posting items about it at http://www.northlight-images.co.uk/stuff/

If anyone has any direct questions - please do ask, and I'll see what I can find out.

Meanwhile, here it is with a Zeiss Flektogon 20/2.8 on it :-)

No real reason - I just had the lens on the desk in the studio :-)

[DaveCurtis]

Hi Keith,

In Michael's 7D review he states:

"Though Canon placed no restrictions on my ability to report on image quality, other than to indicate that any pictures shown are "Beta Sample Images" I am going to punt, and will not be describing in any detail the image quality that I have seen from the Canon 7D.

Frankly, the reason is that I am seeing things which I am not sure are a consequence of the camera's inherent characteristics or are specific to pre-production cameras or even this specific camera. This includes overall image softness and some digital artifacting. Nothing terrible mind you; just enough though that I am aware of it, and therefore don't want to make any undue assumptions. "

How did you find the image quality?

[keith_cooper]

Hi Keith,

In Michael's 7D review he states:

"Though Canon placed no restrictions on my ability to report on image quality, other than to indicate that any pictures shown are "Beta Sample Images" I am going to punt, and will not be describing in any detail the image quality that I have seen from the Canon 7D.

Frankly, the reason is that I am seeing things which I am not sure are a consequence of the camera's inherent characteristics or are specific to pre-production cameras or even this specific camera. This includes overall image softness and some digital artifacting. Nothing terrible mind you; just enough though that I am aware of it, and therefore don't want to make any undue assumptions. "

How did you find the image quality?

I did wonder about this and in general have found that at low ISO, the images compare quite favourably with my usual 1Ds3 (a tad noisier in some ways, but not difficult to fix)

I'm still wanting to get out and do some high ISO night time shots, but have picked up an unpleasant sore throat/cough that I'd perhaps not help by spending any time in the cold damp night air :-(

My suspicion is that some of the reported image issues came about whilst RAW conversion software was being fine tuned. I've also found that if you really want to look at 100% raw files, you can tweak the look quite a bit with sharpening and NR settings. There is softness there, but for overall image quality (at reasonable sizes) I just have not found this an issue.

When I'm looking at a new camera, I'll pore over 100% views, when I'm taking photos for a living, this is a much rarer occurrence. For image quality purposes I'd not often run into issues with the 7D. I've realised I like the somewhat less feature packed approach of the 1 series, and the LCD focusing screen might irritate me with it's huge AF point boxes (line width is just a little coarse IMHO)

I've just been looking at DxO optics Pro v5.3.6 on the Mac (10.6) where the 7D is supported, and it worked well. This release is a temporary one, since V6 will be out for the Mac next year (available for the PC now) and I believe that the V6 RAW conversion engine has quite a few tweaks, particularly in NR.

I always suggest people try some of their own tricky images to convert via the demo, since I believe some of my results with DxO were called into question here, a few years ago ;-) Then again,  I've always believed that real results with a RAW file trumped expert pronouncements :-) :-)

I've a whole load of 7D pictures from a trip to the Post Office yesterday lunchtime - just snaps at 800 ISO with a 24-70 lens. I'll put some up on a blog post later, but my feeling from using the camera in the street was that AF was rock solid and that ISO 800 is perfectly usable for this sort of work.

Given this is the first time I've seriously used a crop sensor camera, I've not often found the lack of wide angle a problem. I don't have my old 16-35 any more, so was limited to the longer 24-70 (Canon just sent me a body, charger and s/w disk)

The only area I've not addressed so far is Video, which is a whole different field to my photography. I'll probably look at it once the 1Ds4 turns up, but so far my brief clips of moving traffic have not really caught my interest...

[keith_cooper]

Some more Canon 7D info

Looking at the metering and WB, along with more general observations

[DaveCurtis]

Interesting!

With this pixel pitch I wonder how far Canon will push next years 1DS MrkIV.

[keith_cooper]

Interesting!

With this pixel pitch I wonder how far Canon will push next years 1DS MrkIV.

Not too much I hope - I'm hoping that they try and push other aspects of image quality more than just lots of pixels - the 7D equates to over 45MP

The jump in performance has to get increasingly difficult to perceive as we move forward, certainly for much of my day to day commercial work.

If the Mk4 is capable of producing incredible images, then does that suddenly suggest that my Mk3 is in somehow deficient? Not that I'd noticed.

However I will say that I was pleasantly impressed by the overall image quality of the 7D, enough that 32MP in a Mk4 won't unduly worry me.

[Panopeeper]

One quick test showed that unlike the 1Ds3 there was no obvious advantage in avoiding the fractional stop ISO settings

The 7D does not have any real 1/3 stop ISO steps (i.e. with associated gain). The 1/3 steps are useful only for JPEG shooters.

The issue is not only that the 1/3 steps do not offer lower noise, but the full stop +1/3 steps (125, 250, 500, ...) reduce the dynamic range by 1/3 stop; therefor avoiding the 1/3 stop ISO steps is obviously advantageous. The -1/3 stop steps have the same dynamic range as the next higher full-stop ISO; their usage is not without problem, for they are using the next higher full-stop ISO level, thus the shot can be "over-metered".

See ISO settings with the Canon 7D for detailed information with demonstration.

Finally, I wonder what disadvantage using the 1/3 stop ISO steps with the 1Ds3 causes. I don't have any such raw files, so I could not analyze the data.

[keith_cooper]

I've just looked at the 7D I've got here and it uses fractional stops if I've got ISO set to Auto in AV mode, shooting to RAW  - and yes I know that auto ISO (and even Av mode) is tantamount to shooting only JPEGs to some :-) :-)

I did say it was only a quick test - thanks for the link, I'll add it to that page.

As to the 1Ds3 info - it's referenced in the 7D article or at http://www.northlight-images.co.uk/article...1ds3_noise.html

The 1Ds3 steps are quite different in appearance, so it seems that there is a different approach to fractional ISO steps in the cameras - I'll leave 1Ds3 DR considerations as an exercise to the reader ;-)

[Ken Bennett]

Thanks for this, Keith. Appreciate it.

[Panopeeper]

As to the 1Ds3 info - it's referenced in the 7D article or at http://www.northlight-images.co.uk/article...1ds3_noise.html

Keith, I don't want to hijack this thread, and it is not really important anyway, but your method of ISO and noise analysis with looking at the black frame shots in ACR does not yield any meaninful result. You don't see the raw data in ACR (nor in DPP) but its interpretation, which is far from what the camera is doing or can do.

An example for the problem is ISO 50 with the 1Ds3 (or with any other Canon DSLR). There is no ISO 50 in hardware; it is identical to ISO 100, except in the metering (it is not a numerical derivative of ISO 100). This means, that the noise and the dynamic range is the same for ISO 50 and ISO 100, but ISO 50 causes an "overmetering" by one full stop (it depends on other factors if that results in overexposure or not). The reason that you see much lower noise in ACR with ISO 50 is, that ACR "makes up" for the one stop too high exposure by applying an implicite negative "Exposure" correction (not shown on the slider) - but that ruines the comparison of the histograms and the blotches.

[keith_cooper]

I think the point is that this is noise that I can see in a converted image - irrespective of where it comes from.

I generally use ACR for conversions, so whilst the goings on 'under the hood' are of definite academic interest to me, it's noise levels that appear in real world images I've converted that matter.

It should perhaps be called 'Noise levels with fractional ISO settings in RAW files converted with ACR Vxx.x' but not nearly so many people are going to read that ;-)

So whilst I respect your more rigorous (and accurate) approach, I'm looking at the noise levels down amongst the shadows in my day to day converted images.

I've finally been out for a walk round at night with the 7D, so ISO6400 noise (wherever it's from) here we come... :-)

[keith_cooper]

Since Canon still have not taken it back, I've added a couple more short pieces covering

High ISO - using the 7D at night

and
A quick comparison of 7D and 1Ds3 sensor resolution

The second was after a request that I take the same shot with a good lens at f/6.3.  No real prizes for guessing that the pixel density of the 7D captures more detail if the lens is up to it.