This discussion has come up before..
To even begin to achieve good performance from the lens, film flatness is a MUST. This is one of the fundamental reasons why going up in film format size makes achieving film flatness difficult. To deal with this problem adhesive and vacuum film holders can be used to help film flatness with increasing film size. Film flatness is one of the fundamental reasons why 8x10 can be a problem to realizing all a give lens can produce.
Camera alignment is another significant factor, folder cameras might not have any where near the precision and repeatability of alignment of standards needed to achieve what the lens can render. Problem is increased with larger lens apertures used. This is why stopping down is often the solution to remedy both these problems.. except lens performance will be reduced as the image taking aperture shrinks... resulting in "sort-of-focus". Not much of a problem if contact prints are made from 8x10 or larger film, problem if the film is projection enlarger to any significant degree.
Glass plates are flat, flatter than film in a film holder.. problem with camera precise and alignment remains regardless of how flat the image recoding device or media is.
This is why process cameras back in the day had vacuum backs on a precision flat film back. Camera alignment was check, adjusted, calibrated. Using a vacuum film back large sheets of film (could be feet x feet in size) could be held remarkably flat as needed for precision graphics work.
Simply going down film format size can make a surprising difference in easing film flatness problems.
Lens performance is one factor out of many that will have an effect on the finished print.
Bernice
Originally Posted by John Layton
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