I'm having quite some difficulty properly focusing my Canon 10-22mm lens for landscape shots with small aperture (f/22) and very near to very far subject matter (a few feet near, to infinity). My results are very inconsistent, meaning sometimes the near is in focus but not the far, and vice versa. And sometimes, it seems, in between (is that even possible?!)
Also, with f/22, I am getting diffraction which is making it slightly more difficult to judge if my focus is on point. There could also be a little noise contributing, but I doubt it, since I am using ISO as low as I can, usually between 100-400, on my 7D.
I read (and have experienced) that for wide angle lens with huge DOF as I describe, focusing is extremely unforgiving if you are off even a little. This could obviously be incorrect, but it seems to be accurate based on my results. I have been focusing manually with the distance scale on the lens barrel, so I am thinking that may be the problem as it is not a precision method.
So anyway, I guess I am hoping for some advice/guidance/help on how to figure out where to focus, at what distance, and if I should do it manually or somehow use AF, and working with near subjects out to infinity, and f/stop, etc. I have no problems with telephoto, macro, and other photography in general; only this wide angle landscape issue is being a stickler
Thanks for any assistance.