02-03-2018 09:44 PM
I have only had the lens for about 4 days and have done just a few hand held shots at f1.2 and most shots were in focus. Tomorrow, I will try on a tripod. A bunch of local photographers said I should always calibrated all of my lens. I have used Canon since the Rebel days and I actually only heard about this AFMA today... (probably saw it in the manual but skimmed over it). Another Sigma Camera/Lens user said he was told if you are using the same manufactuer equipment there is no need as the internal software takes care of this. Implying I would only need to do this with my 70D with the use of let's say a Tamron lens.
What does the forum say on this subject? Thank you!
02-03-2018 11:00 PM
Camera bodies have a tolerance range on settings like focus. Lenses also have tolerance ranges. Sometimes they stack up such that they add together. That can result in the camera saying focus is achieved when it isn’t. AFMA lets you compensate for that. There is no automatic compensation in Canon cameras. AFMA can be applied to Canon and third party lenses.
02-03-2018 11:03 PM
Shooting at short distances hand held at f/1.2 can become really tricky, really fast.
02-03-2018 11:06 PM - edited 02-03-2018 11:07 PM
02-03-2018 11:08 PM
Yes I found that out with my Canon 85mm 1.2 USM (not the L). I found if I leaned on something it would do good, or sometimes I would just do the rapid fire and usually 70% of them were good. I love this new challenge. Been shooting since 1978 off and on, but fairly steady for the past 12 years. The faster lenses are new to me though. My goto lens has been the 24-105l and the 17-40l. the 24-105 though sometimes would backfocus on the wall behind the subject sometimes at unpredictable times.
02-04-2018 09:29 AM
"... he was told if you are using the same manufactuer equipment there is no need as the internal software takes care of this."
Yeah, right ! Funny friend you have of course it is nonsense. But, on second thought, does he have something? Non of my "L" series lenses needed AFMA. I have and have had a lot of them including the ef 50mm f1.2L USM and the ef 85mm f1.2L USM. Maybe I am just lucky because I know others that do AFMA their "L" lenses and I assume they needed it.
I found that out with my Canon 85mm 1.2 USM (not the L).
There is no "non-L" f1.2 85mil that I know of? There is an ef 85mm f1.8 that is not an "L" lens. Do you mean that lens? If you do it sn't even in the same zip code as the f1.2L version. Not at all.
02-04-2018 02:27 PM
Yes my bad the 1.8
The 85mm f/1.8 USM is the most disliked Canon lens that I have owned.
My copy did not focus consistently enough for it to be usable wide open at f/8. At f/1.8, the DOF is fairly narrow at close distances. The lens would not always lock focus at the same distance from the camera. Sometimes it would back focus, and sometimes it would front focus. The variation in distance between the front and back focus, would exceed the DOF when the lens was wide open. To make up some numbers, if DOF was one inch, sometimes it would focus 1-2 inches behind, or in front of the subject.
But, as I stopped the lens down to f/2.8, or narrower, the focus distance variance would be come more and more neglibile, until it was not an issue at f/4. The problem did not go away. It is just that the behavior was simply far less noticeable. Because of this wide variation in focusing distance, it was a moot point to try to figure out an AFMA adjustment with it.