I have heard a lot about this FoCal software for AFMA.
My question is it really worth it?
Doesn't AF vary by distance to the subject too? From minimum focus of a focal length to a more distant shot at the same focal length?
So this software just adjusts the AF for a specific distance of a focal length (assuming you use that same distance quite a bit), if you change that distance from the subject...you aren't going to get that same perfect focus at the same focal length? Am I missing something?
I understand the software can do many other tests, but for the main purpose for AF calibration is FoCal worth it?
It only measures one focal length at whatever distance you set the camera back from the target. How could it do anything different?
However, you can vary the focal length and distance to the target and compare the best settings, picking the one that makes sense to you.
Knowledge is power, and by taking AFMA measurements at different focal lengths and distances, you can be the one who determines the setting.
Of course, if You have a 5D MK III, or a 1D X, there are two settings for zooms - Wide and Tele, and the camera interpolates the AFMA for focal lengths inbetween.
As to distance, most bodies do tend to front focus at minimum autofocus distances, so you do need to test and see if its a real issue.