What distance to be at for AFMA

[-Gamer-]

Does anybody know at what distance or approximately the distance I should be at to AFMA, I'll be using the Canon 400 f/5.6L with the 7D Mark ll?

Overall I'm happy with the photos i'm getting and love the lens/camera combination but there are times when i'll get say, a run of a pelican and 1 or 2 out of 5-7 shots will be tack sharp the other's will be soft. It's not really a big deal for me as I get more keepers then throw aways most of the time but figured I'd give AFMA a try and see how much if any adjustment I may need.

Thanks, everyone, I'll take the advice given here if I decide to AFMA.


I did my 7D2/4005.6 at about 60ft. The recommended 50xFocal Length would be about 100 ft(1.6x factor). Typical working distance, or the distance where critical AF will be most noticeable is usually best. My value of +4 seems to hold true throughout my working range. It's noticeably sharper than without correction. The sharp\soft\sharp thing might be something else. You might need to play around with the various tracking\focusing modes to get that fixed. I still have those issues at times.

Yeah you're probably right, as I have found myself shooting in the wrong AF Case setting when photographing a stationary bird or BIF or vice versa And toss in a lens without IS and a shaky hand at times and well user error seems more the issue in my case

 

[Nethawk]

I've had the best luck with AFMA by choosing a distance just inside infinity focus. It was too confusing, and left me with too much doubt to try and determine what my most common distance was - because I don't have one. If you're primarily in studio this should be easy, for anyone else not so much.

On my 6D, where I can record both sides of zoom, I will use the 50x calculation for the wide end, but always just before infinity for the long.

 

[eninja]

FoCal Test Distance Chart and Explanation here. Two things to note
[list type=decimal]
[*]its the minimum recommended distance, you can be farther. I tend to check lenses at two distances just to be sure - the minimum and 2X the minimum is my default.
[*]you do a teleconverter in the focal length, but you don't consider the crop factor in the focal length when deciding the distance.
[/list]

So 8m is the minimum recommended for your 400mm lens.

But how about a target, should I resize target as I go further? If yes, what is the ideal target size (width of strips, of black and white)

Because in my experience, when I go further, AFMA green/yellow dot go crazy, no pattern at all, it never stay solid. So I tend to go closer to my target.

Hope my question make sense..