50D Sharpness

I've had some difficulty getting sharp images across all focal lengths on my 28-135 zoom, and some frustrations as well with my new 100mm f2.8 Macro. I've just read a long review of the 50D where it referred to something called DLA which causes a loss of sharpness due to a difraction angle on fstops smaller than 7.9? This article suggests a reduced image size to allow smaller aperature use without this blurring effect.


Any comments on this?


Also what may appear to be a basic photographic question - but one I frankly don't know the answer to. When a lens is focused at infinity, does fstop impact depth of field? I find myself angling towards smaller fstops to ensure DOF, but if it's not a concern at infinity, as suggested by someone who will for now remain nameless, that would make my air show photographyfar easier.... I do know it is less of an issue at non - macro distances, but this person is suggesting it is a non-issue when focusing on objects that are at infinity. Your comments would be appreciated.

It probably wouldn

Also, your not going to notice a loss in sharpness just because you are over 7.9. But with macro especialy you might notice when you start geting past F11 or F13.


The best way to do Macro is use live view. Magnify to 10x and manual focus. If you can