With all the talk about how lens diffraction limits of lens are correlated on the 50D’s 15mp sensor I decided to do my own testing to decide what camera to keep and which to sell.

Here I pulled out my trusty stuffed Ptarmigan again and did a controlled shoot at various apertures. However, this time I only compared my 1.6 crop cameras - the 50D to 20D.

With each camera I shot mirror lockup with a 500 f/4, centre focus on the bird’s eye. Took pics at f/4, f/5.6, f/8, f/11, f/16, f/22 and f/32. Took the best of each grouping and processed the RAW file in DPP using shot settings, standard picture style and did a level 3 sharp for the 20D and a level 5 sharp for the 50D. Some minor levels in PS and took out 100% crops of the head area (about an 80% crop).

Notwithstanding the megapixel advantage, to my eyes F/4, f/5.6, and f/8 showed the 50D as a clear winner. I would say f/11 was on par, maybe a slight edge at f/16 to the 20D; and 20D was clear winner at f/22 and f/32. My conclusion is that the 50D is a keeper for what I want with it - shooting birds and wildlife(which are normally shot between f/4 - f/11).

In the context of diffraction limits, I would not recommend the 50D for macro’s and landscapes, which is of no concern to me as I use the 5D for both.