Nifty fifty STM - focus issues, or human error?

Started Nov 16, 2017 | Discussions thread
OP TMHKR Forum Member • Posts: 65
Re: Nifty fifty STM - focus issues, or human error?

plantdoc wrote:

Based on your description, I believe your camera and lens have a focus problem using the OFV. Probably either front or back focus. Rather common unfortunately and exposed by fast aperture with shallow depth of field. Canon refuses to provide the fix by adding MFA to Rebel cameras. Probably would cost very little or nothing. I quit using Rebel cameras for this reason. Now using a 70D with MFA as needed or M5 which is always live view being mirrorless.


I don't believe it's front or back focus issue, since front or back focusing would be constant, not random like in my case. I believe the actual cause is phase-detect sensor being fooled by wide apertures. I've done some research on phase-detect system last night - it's faster, but less accurate than contrast-detect system (and tends to "jump" from time to time). When I stop down the lens, it performs pretty good.

At least my camera has the Hybrid CMOS AF (first generation, but it's better than nothing) which increases Live View focusing speed to an extent.

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