40D to 7D

I am a birder and currently have the 40D...which is a great bird camera. It is though only 10mp and that works fine.

The 7D is 18mp.....my question is...since I will ''crop" pictures as I shoot from distances and birds are small, will the extra 8mp that a 7D provides over the 40D essentially equate to having a 1.4 TC? If I crop, the 18mp will allow me to crop and still have better quality, more so than cropping the same image on a 40D? jim

cropping the same amount on a 7D as a 40D should result in a picture with more detail. However, if you crop a 7D 18MP image to 10MP I don't think the IQ will equate to a 40D ... others can correct me if I'm wrong.

But apart from that, it's correct. A 1.34x teleconverter, to be more exact.
And the image would look better than it would if you enlarged the center of the 40D's image the same, I'm pretty sure (not that I've tried exactly that, even if I have both cameras you are talking about).

Just enlarging the center of the image from the 7D will of course also enlarge all imperfections. But I think in general that the 18 Megapixel images from the 7D allow for quite a lot of enlargement.

Apart from the 1.34 factor (1.34^2 = 1.8) - as noted earlier you also get better ISO performance and it may be key for dusk/dawn shots and you get a much better AF system
all in all the 7D is a worthwhile upgrade to your very good 40D

Thanks...question answered...No doubt I realize the benefit of...just need cash! jim

I have both the 40D and 7D. I think the noise you see in the 7D images is much nicer and cleans up better than what you have with the 40D. So after cropping your 7D image down to 10MP, my opinion is that you are left with a better looking image than you get from the 40D.

The smaller, grainier looking noise in the 7D cleans up nicely enough that it feels like you're getting an extra stop or more of ISO as well, so you can crank up your shutter speed a bit more if you like. Keep saving the cash, you won't be disappointed.