I don't dare say something like it's a problem endemic to the lens in general, but boy it sure seems like it could be. As I said earlier, it would explain William Castleman's results showing the lens taking a steep dive in sharpness after f/2 or so. :shrug: The behavior would also illuminate why some people never see the problem - if you only shoot between f/1.2-f/2, the problem isn't very apparent.
It will be very interesting to see how the next lens performs.
FWIW, to the 50/1.2L's defense - it backfocuses more consistently than any lens I've ever had! But seriously, its focus consistency is noticeably better than the 50/1.4, which is one of the reason I wanted a 50L to begin with. It's a shame it's just so consistently OOF.
On a brighter note, as I mentioned to Gary when I purchased the lens, I bought it with my AMEX card, and customer satisfaction seems to be very important to them. I'd hate to suggest bringing them into the mix, but with this kind of pricetag, who knows.
If the retailer will exchange it for me, I'll try one more. If not, I will send it back and forth to Canon until it's right even if it takes a couple of months.
And to agree with Sam, the focus consistency in general with the 1.2 is worlds better than the 1.4.
This may be a silly question but I will throw it out there, for those that notice the backfocusing, what body are you using and for those that seem to have no problems the same question.
1Ds2 and RebelXT. Both bodies show backfocus and / or focus shift on the 50L f/1.2s that I have tried...
And, both bodies work perfectly with my 85L I lens, and worked well with my last copy of the 50L f/1.0.
To Ed, Canon Irvine had my 1Ds2 on the last calibration attempt of my first 50L f/1.2, and said they did not touch the body because it showed to be in good calibration. They used my body for reference and calibrated that lens twice (because they were not happy with it themselves after the first attempt) but they still did not get it right....
Ohhhh, they adjusted the lens where it did not backfocus at close distances...
But in doing so they induced FRONT FOCUS for subjects at further distances... (they basically reversed the problem) So no,...I would not send the body and I doubt if it would make any difference anyway.
It wouldn't be so bad, if Canon said they found a problem and are working on the fix, at least then people would feel like Canon cares for their customer base, instead of just selling them caveat emptor.
ghuff wrote:
1Ds2 and RebelXT. Both bodies show backfocus and / or focus shift on the 50L f/1.2s that I have tried...
And, both bodies work perfectly with my 85L I lens, and worked well with my last copy of the 50L f/1.0.
.
Gary I tried on both my 1dmk2 and 1dsmk2 and both exhibit exactly the same problem as you. Then I change the lens to the 85F1.2 and the focusing was spot on. So my lens is a lemon as well.
I just got off the phone with my usual rep. at a major online Canon dealer. The rep said:
A. He couldn't find any records of returns of the lens.
B. Sales are notably below expectations.
So the lens is overpriced and most, if not all, copies are bad. Canon is lucky they overpriced the lens. If more people had copies, Canon's reputation would suffer even more than it already is.
my second copy is definitely a dud. it backfocuses at close distances using AF wide open. MF fixes this problem at f/1.2. stopped down to f/4 and manually focused, it will noticeably backfocus. i have never had a lens do this.
the date code is UU1200 so it's quite new.
oh well, it's going back to the store and i'll be trying to find another copy. i'd really like to have this lens in my bag.
To tell you the truth I played with the lens a little and just did not see enough between my 1.4 and it to warrant the price. Asside from saving all that money. It sounds like I may have saved myself some head aches as well.
ghuff wrote:
What happens is the focus point appears to shift dramatically as the lens is stopped down, and it is not that uncommon for lenses to have it.
So are you saying it's basically something like dealing with perifocal lenses, except with stopping down instead of changing length? So if you lock focus and stop down, you would no longer have accurate focus? Wouldn't AF system compensation for it require refocusing?
Yes, and it is being refocused...problem is the Canon system (and maybe others) focuses WHEN the lens is WIDE open. Then it only stops down to the selected stop when the shutter button is pressed, leading to the focus error. Understand?
What modern AF systems supposedly do for this condition is that the camera senses the f stop you have selected and changes the actual focus point by a programmed amount to compensate for the focus shift that the lens characteristically exhibits..
Whether this actually happens or if the 50L actually exhibits this condition is not certain. My observations were speculation of what I think is happening.
No matter where I put the focus point, regardless of aperture or distance to target, and as long as there's good contrast, the focus seems to be spot on. For the record, I don't doubt that any of you are having issues with your 50Ls. I just haven't experienced what's being reported and I doubt that I will. Even if my glass did have problems, I'm now past the 30 day return period. My only recourse would be to let Canon fix it. But again, I don't forsee myself needing to do this because I just do see any problems.
BTW, my wife and son are away, so I don't have a subject to do the eyeball test on, but I will see if I can't find a willing subject at work on Monday. Wish me luck!
As bad as I want to join the back-focusing club, I just can't. Sorry.
I'm also using a 1D2N for all my shots. Haven't really tried it on my 1D, but I suppose I should.
No, you really don't want to join the club. But thanks for posting these. My first lens could not pass this test wide open, and the second could pass at f/1.2 but rapidly started backfocusing at above f/1.2. So I am glad to see your results that show your lens can pass this test.
And yes, PLEASE try it on your 1D and let us know how it does.
I do see one possible difference though in your test shots versus mine. My test focus chart was flat for all of my tests. Both my lenses exhibited slight barrel distortion. In other words the "focus here" line was bent oppositely to yours...mine was convex (barrel)...but yours appears to be concave (pincushion). SO the big question is..... WAS your paper flat for this test? And if so, this pincushion distortion MAY be a sign of what correctly adjusted lens elements are supposed to do...since your lens does not seem to backfocus.
But seriously, its focus consistency is noticeably better than the 50/1.4, which is one of the reason I wanted a 50L to begin with. It's a shame it's just so consistently OOF. 
(they basically reversed the problem) So no,...I would not send the body and I doubt if it would make any difference anyway. 
