Mon 12-Nov-12 03:53 AM | edited Mon 12-Nov-12 03:55 AM by jamesvoortman
I like the method and will try it.
I have a small issue with the advice to shoot at minimum focussing distance. How do we know that the focus point correction applied at this distance will be applicable to normal shooting distances for the respective lens? For zoom lenses, will it be the same at both wide and long settings? I would rhink the best is to carry tests out at normal working distances for the lens involved and for zooms to check the correction required at several points over the focal length range, choosing a correction that it either averaged or appropriate to the most commonly used setting.
Therefore for macro lens : Very close working distance and small image area.....A test page with finer dot pattern might be a good idea.
For 80-400VR : The most critical sharpness requirment is when shooting birds - usually done at 4m to 10m with this lens. Again the target may not be of appropriate size.
Wide angle and standard lenses I use normally for general purpose and landscapes - frequently used with distant focus not practical for this test so obviously I will conduct the test at reasonable working distance and hope the results translate to longer focal distances