D600 Backfocus

Started Sep 23, 2012 | Discussions thread
Big Daddie Contributing Member • Posts: 936
Re: Is there a specific Autofocus mode that is best when checking back focus?

leicaman wrote:

Is there a specific Autofocus mode that is best when checking for possible back focus problems?
Bright or low light?

Single-point only. Camera on tripod, period. Absolutely no hand-holding. Some people have a tendency to shift the camera forward or back while pushing the shutter.

In-between test shots, the camera must be mis-focused so it is sure to attempt to re-focus again. With an AF-S lens, just twist the focusing ring to infinity. Or stick your hand in front of the lens and have it try to focus.

Remember that focusing is surprisingly not as 100% repeatable as one might think, so repeat each focus test at least three times (take three shots, mis-focusing between each one).

Natural daylight. Definitely not indoor artificial light. (Often we see people posting photos of their focus charts and one sees the white balance -- or lack thereof -- of incandescent lighting.)

While the angled focus test chart is quite popular, I've never been a fan of it. Since the AF sensor usually taller and wider than that middle line, it's easy for the camera's AF to front-focus on the target and be mis-read.

Tools like Lens Align present a flatter target. I've also used the sides of juice boxes, spaced far enough apart that the central sensor can't be grabbing on to them, and the two side ones staggered slightly forward and back of the center one. If the rear box is sharper than the center one being focused on, that's back-focus.

Good luck with your test.

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