The AFMA myth.

Started 5 months ago | Discussions thread
Zeee Forum Pro • Posts: 19,777
Re: The AFMA myth.

Most of my newer Canon end lenses don't need much. Usually a few ticks + which I figure is because the factory calibrates 1/3 - 2/3 and we go 50/50. There is also slight variation in manufacturing which is normal. There is even variation in phase detect if you compare 20 shots in a row. Not much you can do about that.

Two Canon service reps told me that for big adjustments MFA is an emergency measure and the gear should be sent in for inspection, which I did once for my 70-200 II which was way out. I'm not including 3rd party or lenses with known issues. Even though I could have left it at +14 @ 200mm but I paid a lot of money for it and it isn't my responsibility to correct production problems. Canon found a miss-calibrated board.

I often get beat up about my view but a few years ago I did find an article that supported my thoughts on this. My threshold is +-5. I'll start to think about it from +- 5 to 10 and it goes in over +-10. All my lenses except my 70-200 have never crossed the +-5 threshold.

Sections 10, 11 & 12.

I use FoCal to calibrate. I try to use as much natural daylight as I can and I light the target with 2 daylight balanced studio CFL's. Even Canon started to mention light in the most comprehensive instructions to date. First time they mention usual shooting distance or 50X if that is not possible in one document.

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Canon EOS 7D Mark II Canon EOS R Canon EF 300mm f/4.0L IS USM Canon EF 70-200mm F2.8L IS II USM Canon Extender EF 1.4x III +8 more
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