We'll take this opportunity to stress that you cannot expect accurate focus results 'out of the box' for a F1.4 prime on your camera body, no matter what brand of camera and lens is in question. That said, performing this sort of calibration on just your center AF point will typically lead to drastically better results with fast lenses, such as F1.4 primes. We'll warn you that this can be a bit of a rabbit hole - when you look for problems, you'll find them. Therefore, it's useful to know when other AF points may be problematic. AFMA and AFFT only globally affect all focus points, so you'll typically want to optimize for the center AF point. Although manufacturers try to calibrate all AF points in camera bodies, sometimes some points are off relative to one another. FoCal even allows you to test each individual AF point on your camera body, which can tell you (1) if your camera body has problems ( a la Nikon D800 left AF issues), and (2) which AF points you may wish to avoid. This allows you to 'tune-in' the best calibration values for your shooting day/scenario.
By automating the process, FoCal allows you test multiple combinations, subject distances, and on different days, easily. Sigma's USB dock takes care of one of these problems, allowing you to program in the best calibration value for four different subject distances into their lenses, but no camera manufacturer makes it easy to actually determine these values. Further frustrating things is the fact that the optimal value can change due to conditions like temperature and humidity, as well as subject distance, making it rather difficult to nail down the optimal settings. Calibration options are typically available under 'AF microadjustment' (or AFMA for Canon and Sony bodies) or 'AF Fine Tune' (AFFT for Nikon bodies) menu items, with the process being pretty laborious and relying on the user to shoot many shots, throwing off focus in between each shot, to determine the optimal AFMA or AFFT for any camera/lens combination.
#Reikan focal software update
Reikan has announced a major update to its AF tuning software, FoCal. FoCal automates the process of calibrating your lens to your DSLR camera body, important - if not absolutely necessary - for critical focus when using fast lenses that yield shallow depth-of-field.
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