Expletive deleted

As a "proud" owner of an EOS-1D Mark III I've had some interesting, amusing and downright farcical moments dealing with the autofocus on that camera. I have said that the 1D3 acquires focus faster than any other Canon, but that it acquires AF on the background faster than any other Canon. My relatively ancient Mark II works better for birds in flight since it makes a stab at tracking a Northern Harrier in flight rather than focusing on the treeline faster than a weasel on crystal meth, which is the strong point of the Mark III.

So I had great hopes for the 1D Mark IV since you couldn't imagine Canon messing it all up again. After all, the IV is their flagship SLR body, their ultimate photojournalist machine, and I was starting to look forward to retiring the Mark III and getting a Mark IV or Mark IVs to replace it with.

Imagine, then, my joy at reading this article:
http://www.robgalbraith.com/bins/multi_page.asp?cid=7-10048-10484 ;

which suggests that the 1DIV is really just a different breed of cranky to the 1DIII. Somebody just shoot me now. (I actually started checking out Nikon 600mm f4 VRs this afternoon). The 5D2 is sluggish, the 7D is soft, and the 1DIV is cranky. Is there someone in Canon Japan that I should visit to slap some sense into them ?

For what it's worth, I have no doubt that Galbraith's mammoth article reviewing the AF performance on the Mark III:
http://www.robgalbraith.com/bins/multi_page.asp?cid=7-8740-9068
was right on the money. Roger knows how to point a camera and engage autofocus - he does it for a living, unlike us dilettantes. The 1D3 certainly has its moments but after being somewhat burned on that SLR I'm rather reluctant to drop $5K on another turkey. (The 1D3 focuses just fine on Wild Turkeys, just so long as they aren't moving that fast).

Looks like I'm using the 5D2 again this spring.

Tests on 5D Mark II settings

Prompted by discussions with a friend concerning his new 7D I did the following tests on my 5D Mark II :

1. Default Picture Code settings do not affect RAW file appearance in Lightroom. Not a great surprise this, since RAW files are supposed to evade most or all processing policies that effect in-camera JPG files. I shot an IT8 target with RAW+JPEG. Of interest was that there was some difference in color reproduction in the reds between "Faithful" and "Neutral" in the JPGs.

2. High ISO Noise Reduction settings do affect RAW appearance. This test was shot against a defocussed white wall (i.e. "featureless" image) at 2 stops underexposure at ISO 1600. There was a marked difference in appearance of the JPG files, with much less evident grain in Standard and Strong settings than at Low or Disabled. Standard was fairly close to Strong. This pattern was also evident in file sizes (more noise = larger files). For the RAW files there was a subtle difference for the same shots - more or less invisible for the lower ISO (400?) that I tested the previous evening but just visible at ISO 1600. I did not test sharpness reduction, but that's the usual trade-off. Canon, however, in this document, indicate that Adobe Camera Raw ignores this setting.

3. Noise patterns at all ISOs. Everything from 100 to 3200 in 1/3 stop increments with the same -2 stop underexposure as the previous test. Notably, stops 1/3 below the "standard" ones showed less noise, but also a little more exposure. In fact for ISO 160 the featureless noise shots perhaps showed nicer noise appearance than ISO 100. The 5D Mark II has this tendency to produce grid noise artifacts at lower ISOs. The ISO 1/3 stop above the standard ones fared least well. This pattern has been commented on previously at the Dpreview.com forums, and despite the high bs level much of the content in those forums, it appears to have a basis in fact.

More megapixel obsessions

Starting this May I largely stopped using the professional level EOS-1D Mark 3 and have subsequently mostly used the EOS-5D Mark 2. The autofocus performance of the latter is quite a lot worse, particularly in flight, but I had found that the images were noticeably sharper in some instances and generally had more "pop". I still use the 1D3 for flight shots.

I process RAW in Lightroom so in principle things will be normalized but there is a real difference in image quality. The 5D2 has many more pixels (21.1 Mpix vs 10.1), and more per square mm since the 1D3 pixel density is equivalent to 10.1*1.3*1.3 = 17.1 Mpix. The factor of 1.3 comes in because the APS-H sensor on the 1D3 is smaller than the full frame 5D2. The 5D2 appears to be sharper even on a per-pixel basis probably because of a weaker aliasing filter.

Enter the newly-announced Canon 7D which is the common APS-C sensor size (1.6x crop factor) and 18 Mpix. Running the numbers the 7D pixel density is equivalent to 17.9*1.6*1.6 = 45.8 Mpix on a full frame size. No, that's not a typo. It has twice the pixel density of the 5D2 and almost 3x that of the 1D3. You can't ignore that.

There will be the usual concerns about noise level at higher ISOs, and how much actual sharpness you can realize off any lens combination. If you shoot the 17-40/4L wide open the actual resolution of the lens is worse than that of the chip. However the supertelephotos that I use have a lot of inherent sharpness. Some of that sharpness is lost when using the 1.4x teleconverter - it's not difficult to see that in test shots but I can also see it in real life photos in the rare situations when I get to take the 1.4x off.

Which brings me to the thing that most excites me about the 7D - thinking about the number of megapixels on the subject using different lens combinations. This is the same thing as considering pixel density, but adding in a factor for focal length conversion. The equation normalized to full frame is pretty simple:

Effective pixels = Mpix * chip-factor * chip-factor * focal-length-factor * focal-length-factor

Chip factors are 1.0 for the 5D2, 1.3 for APS-H like 1D3, 1.6 for APS-C like 7D. Focal length factor is normalized (i.e. 1.0) to a 700mm f5.6 which is what I use with the 500mm/f4L + 1.4x. (Edit: updated for a 16 mpix APS-H EOS-1D Mark IV, aka 1D4).

These are in Mpix on a "subject" of the same nominal size, so bigger = better.

	1D3	1D4	5D2	7D
500mm	8.7	13.9	10.8	23.4
600mm	12.6	20.2	15.5	33.6
500+1.4x	17.1	27.4	21.1	45.8
800mm	22.3	35.7	27.5	59.8
600+1.4x	24.6	39.4	30.3	66.0

The absolute #s are not relevant because you couldn't image a subject with that many Mpix on it, but the relative numbers hold. I could shoot with the bare 500mm f4 on the 7D and have more pixels on a subject than the same subject with the 500mm+1.4x on the 5D2. Depending on how much these lens combinations outresolve the 7D sensor, and issues with the aliasing filter, the 7D could resolve as much as twice as much detail as the 5D2 for telephoto-type subjects where the subject does not fill the frame. The 5D2 still wins for landscape subjects where the 1.6x crop factor on the 7D kills the widest focal length one can achieve.

Apart from sharpness the wider apertures of bare lenses w/o teleconverters allow lower ISOs or faster shutter speeds to be used in dark conditions. As the analysis indicates it's worth taking a very hard look at this camera for bird subjects because there might be a substantial effective resolution gain. Remains to be proven, however, as many factors can come into play to degrade image quality.

Update: the general vibe on the Dpreview forums is that the 7D has lower image quality than the 5D Mark II - this not really being a surprise since it was packing nearly as many pixels into a far fewer chip. It also has less latitude for overexposure (perhaps as much as a stop). It seems there is still no free lunch for smaller pixels. Since the 1D Mark IV has smaller pixels than the 5D Mark II, it will be interesting to see comparative reviews of the latest 1D series increment.