Quote Originally Posted by fhovie
Just from experience - here - I have ruined so many LF negatives by being concerned about over stopping. I wind up with DOF problems when I am reluctant to stop down. Since I started stopping down without fear - the negative quality has gone up. I have yet to see it in my own work where lens diffraction was in any way apperant. Of course in cute little film it might really be a consideration but for MF up to 8x10 - Stop it down - Get the dof - I don't have scientific charts or data for all this - Just a drawer full of expensive experience. I believe it was the"f64 club" not the .... f - can you get that down to f22 'cause I might get difraction club.


Ok - it drove me insane and now I am recovering from that. sorry for the rant -
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.

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.