Canon 24mm F1.4L II inconsistencies

So we've had a couple people in the photo sharing thread for this lens including myself have multiple copies with inconsistent focus. I am not talking about front or backfocus, I'm talking completely random focus. Sometimes focusing a few feet in front of you when aimed out in the distance...other times being dead on.

I am curious if anyone here has resolved their issue with going through enough copies or if its a batch problem at Canon. I don't want to keep spending money shipping these items back only to get another that doesn't work.

My Canon 17-55mm F2.8 and 100mm F2.8L both work pretty darn well with my new 7D from recent tests. At least as good as my 50D.

All Canon fast primes seem to be pretty bad when it comes to focus repeatability unfortunately. Some will deny it, but it seems true unfortunately for me at least, based on my experience with 35, 50 and 85 lenses

Generally lack of contrast, distant/small objects in frame, non flat objects, makes it worse

It took me two copies of the 24L II to get it consistent. The first was all over the place so I returned it for another and it's much better. It needed +12 MA on my 5D II to get rid of some front focus, but that's what MA's there for.

I will say though that ALL very fast primes will mis-focus occasionally due to very narrow depth of field (even on the 24 at close distances) and if you're trying to focus on something that's relatively indistinct for the sensors to lock on to. I think the EOS 1 series are more reliable, but I can't be sure as I don't have one. The centre point on my 5D II is OK, but the outer ones leave a lot to be desired.

Here's an interesting article on fast lenses:

https://www.lensrental​s.com …with-wide-aperture-lenses

As for the lens itself, it's fantastic!

Not sure if it helps you, but... I've owned this lens for about a year and never had any focus inconsistency problem. Maybe I'm just lucky. To be honest, I'm extremely satisfied with the lens. The only bad aspect is that the lens hood doesn't sit tight enough on the lens and can be accidentally rotated slightly and if you don't notice, you will end up with black corners in your photos. Good luck in resolving your problems.

When I got my new 24 f/1.4L II, I had to MA +18. I sent it to the Irvine Canon Service Center and it's been consistent and sharp. Have you tried Live View focus?