Quote Originally Posted by HDNitehawk
It would seem logical to do it this way, in the field you could just set up on any point, do a focus and then a 10x check just to make sure you were hitting your target.

Upon further reflection during an otherwise relatively boring flight home to Boston after a day-trip to New Jersey (business - I wouldn't go there by choice...), I think I see a flaw in the logic.


I guess the limitation on the Live View method is the resolution of the LCD on the camera. With this method, you are in large part judging best focus by the sharpness of the 10x magnified image on the camera display. How many times does something look nice and sharp even when zoomed all the way in on the on-board LCD, but when you transfer the image to your computer you find that it's a little off. That's why the 'unofficial but Chuck Westfall-recommended so as official as unofficial gets' procedure for AFMA involves viewing images at 100% on your computer to judge sharpness.


I think that's an advantage to a tool like the LensAlign - you're setting AFMA based on a DoF scale, so that the plane of focus is centered on anangled rulerthat'sprecision-aligned to the focus target. I find that my quick reviews on the LCD (to make sure I've got the optimal adjustment bracketed within +10 to -10) usually give an estimate that's close to the final chosen setting (but not always exact, usuallywithin 1 or 2 units). The ruler means you're partly judging by sharpness, but really by the location of the region of sharpness as it moves along the ruler from setting to setting, as opposed to within-shot sharpness. Of course, after selecting and applying an AFMA to a lens, I always re-check the sharpness of AF shots in a 'real-world' setting (often my daughters eyelashes) - but again, that's checking at 100% on the computer.


--John