I certainly can't argue with Franks experience. However, I know that in my epxerience any format that is enlarged to any degree that defraction is noticeable...at least to me. Howard Bond,among others indicates that he does not go below F32 if possible on 4X5, F 45 on 5X7, and whatever it takes on 8X10 and larger. I don't have a problem with anything that I contact print. I do however have a problem with anything larger then a 11X14 print from 4X5 for instance...that is where defraction starts being noticeable. It shows up as visibly progressive softening of sharpness.
Originally Posted by fhovie
Too often, it seems, stopping down excessively is an attempt to circumvent taking the time to adjust the view camera properly before stopping down. I have heard other photographers indicate a lack of concern with defraction effects...however they seem to be in the minority.
If anything it is in smaller formats that defraction effects are less a problem then in large formats. It is a condition of aperture dimension compared to lens focal length. As focal length increases and film format size increases the effects of bending light also become more apparent.
I have no argument with what others choose to be acceptable. I know what is acceptable to me.
I just came back from making three 8X10 exposures this morning...lens focal lengths of 375 and 450 mm. My smallest Fstop was F22. The negatives will be sharp.