Originally posted by jatrax The one question I have never had answered was how using a crop sensor affected this.
1) On a FF lens such as a Pentax-A can the marks be used as is or do we need to add a stop? I believe Rio Rico felt that the marks as is were for FF and had to be adjusted for APS-C. Others disagreed.
2) On DA lenses such as the 15mm and the 21mm were the marks designed for APS-C and thus should be used as is or do they also need adjusted?
Lens DOF scales are appropriate for the intended format. The numbers for FF are quite different than for APS-C
The whole matter of the DOF scales is sort of strange in that they vary across makers for a particular focal length. Those on my Russian and former Soviet glass are very optimistic while the Japanese lenses are less so but still vary between brands. I guess tomorrow I could gather several examples together for a group shoot
If one must be precise, I suggest using a DOF phone app and place the focus scale at the appropriate distance for hyperfocal at the desired aperture.
Examples for APS-C using DoF Android app:
DA 15 at f/8 is hyperfocal at 4.7'
DA 21 at f/8 is hyperfocal at 9.1'
DA 35 at f/8 is hyperfocal at 25.2'
Examples for FF using the DoF Android app:
FA 20 at f/8 is hyperfocal at 5.5'
FA 35 at f/8 is hyperfocal at 16.9'
Steve
Last edited by stevebrot; 03-06-2016 at 12:11 AM.