It hung around for quite a while as it was intently study a vole in the field ahead of it, which it subsequently caught and flew off with. This gave me the chance to change around body, lens and converter compositions to see how things looked and how the crop worked.
The first two images are full frame in terms of crop, and then I will do some 100% pixel blow ups. (Click on the image to see it larger)
5Dmk2, 500f4, 1.4EFTC, 100% of the image
7D, 500f4 (no TC) 100% of the image
Summary - the 1.4 on the 5D nearly makes up for the 1.6 crop factor on the 7D. Both images are within 1 kelvin on the colour temperature, but the 7D is warmer due to it being shot about 20 minutes earlier, and the sun was brighter.
5Dmk2, 500f4, plus 1.4EFTC, crop at 100% pixel enlargement - Unsharpened!!
7D, 500f4, crop at 100% pixel enlargement - Unsharpened as well!!
I am pretty happy with this as neither has been sharpened. The 5D was at ISO400 and the 7D at 125 (for some reason! - should have been at 100 as I only usually use whole stops, but maybe should have it at 400 for a truer comparison)
5D, 500 + 1.4 - cropped for presentation and sharpened
7D 500, cropped for presentation and sharpened as a direct comparison with the the previous one.
As can be seen from the first two images as the full originals, to get to a useable crop there has been pretty big crops.
Now if we put the 1.4 EFTC on the 500 and 7D, then the subject is much better sized in the frame (obviously) but does mean a lot less pixels are thrown away in the resizing process.
7D, 500f4, 1.4 EFTC, 100% of the image, no crop
And given that the light was good I also added the 2x EFTC, and again at full size, we now have an image that we need to throw away virtually nothing and retain all of the available quality. Now of course the 2x does compromise IQ and there are some losses but as we have said before on here, if you have great light, a good steady solid platform and stop down to at least f11 or thereabouts, you can get some good results with it. In Live view mode, I also found that the AF still worked with the 7D, and it shouldn't if you read the specs, unless somebody knows otherwise.
Landscape and portrait variants with the 7D, 2 x EFTC and 500 - both full frame
So conclusions!!. Apart from the ability to pick and choose your reach by virtue of crop, factor, lens length and converter size, I am not particularly sure that I have proved anything other that that the results are very similar between the 5Dmk2 and the 7D on this particular image. Does it matter? For me, not really as I am very pleased that there is this level of consistency and I stress for this type of image.
Clearly what I have shown here is very limited and not really scientific in any way.
But it did prove, at least to me, that the pixels on the 5D are very good, but then I am not sure that that was ever in any doubt.
Where I will expect to start to see differences will be in the full frame depth of field effects when I start doing a bit of macro work later in the year, and also where the subjects are closer with the longer lenses.
But I like the 5Dmk2 that is for sure, and after the 7D the handling is so similar as to make no significant difference.