Impact of UV filter on sharpness of shot
I photographed a kitchen yesterday that my cabinet shop produced.
The shots were taken on a tripod with a Canon 5dmk2 and 24-70L lens. They were shot at 7.1F stop @ ISO 320.
Ordinarily I shoot these tethered to a laptop so I can see what is going on but yesterday I just relied on the little screen on back.
The images were pretty good when I looked at them on the computer albeit not as sharp as I expected. I used auto focus mostly and dialed the lens in until it beeped at me. There were only a couple of shots that the lens could not find enough contrast to lock onto so on these I switched to manual focus.
THREE QUESTIONS (maybe more later)
I keep a UV filter on the lens, not so much for UV protection as to merely protect the glass on the L lens from being scratched. I forgot to remove it for this shoot.
1) Does keeping the UV filter on the lens create diffraction that would contribute to a lack of sharpness?
Also, what is the best approach to AF selection?
2) When shooting with auto focus should I let the lens be in charge of AF points?
(i.e. have all the red AF points lit up)
3) Is selecting a particular AF point only for when the lens is set for manual focus?