Sam Bennett wrote:
Mine did the same thing on my XT. I'm not going to call you a liar, but it does appear that a high number of 50/1.2L are exhibiting this problem - even William Castleman who generally likes the lens has confirmed that his does it as well. It's quite easy to imagine that some people simply don't see the problem because they don't shoot in situations that would show it. If you shoot wide-open most of the time, you're not going to see. If you don't do close up shots, you're not going to see it.
I get it. Your not calling me a liar. You are calling me stupid. Just kidding... I have done extensive close focus testing with this lens. Mine was not back-focusing on my 5D but the DOF was asymmetric around the target. IOW, there was alot more in focus behind the target than in front. BUT the target was still in good focus.
If you still have the lens try switching to one the non-center focus points. Once I did that I get a perfect symetrical DOF around the target.
Really, really not trying to call you stupid. It just seems like the overwhelming evidence here is that the lens backfocuses stopped down. I do still have the lens, but I don't see why I would use an off-center point to test with. What would that tell me, really?
mbailey wrote:
. IOW, there was alot more in focus behind the target than in front. BUT the target was still in good focus.
For what it's worth, it is my understanding that that is how DOF should be distributed. A crude rule of thumb is 2/3 behind the target and 1/3rd in front.
Has anybody talked to Canon service about this close focus problem? Are they aware of it? Can they tweak the AF in close ranges to fix it? I would think a tech person at Jamesburg or the other Canon repair place, would be delighted to hear about this close focus problem. They are pretty easy to get on the phone... here are two numbers I have: (732) 521-7000 and 800-828-4040 Would love to know what they think.
RoyPertchi wrote:
For what it's worth, it is my understanding that that is how DOF should be distributed. A crude rule of thumb is 2/3 behind the target and 1/3rd in front.
Although many beleive in this rule of thumb, it is (almost) never is true. When DOF is much smaller than the distance to the subject it is distributed as 1/2 and 1/2.
RoyPertchi wrote:
Has anybody talked to Canon service about this close focus problem? Are they aware of it? Can they tweak the AF in close ranges to fix it? I would think a tech person at Jamesburg or the other Canon repair place, would be delighted to hear about this close focus problem. They are pretty easy to get on the phone... here are two numbers I have: (732) 521-7000 and 800-828-4040 Would love to know what they think.
My lens has been to Canon NJ already. I didn't specify focusing under 3ft when I sent it in, however. I believe one of Gary's lenses took a trip specifically with close focus on the workorder, iirc.
As I thought, Sam. I think a tech would be delighted to learn explicitly that a bunch of serious users on this board have identified a close focusing problem with this lens, under three feet. If I had one, I would make every effort to reach a tech, just to talk it over.
Been there...done that 3 times (trips to Irvine)...did not work...Canon was mostly just confused as to what to do with the lens, and calibrated it TWICE themselves on the last trip cause they could not even get it to suit themselves.
Then they offered maybe a trip to Jamesburg for a second opinion?
NOPE. I sent my lens back to the dealer and got another...and yes it did the same thing. Sent that one back also.
The techs may be interested, but I don't think they really have a clue what to do if it is not in their manuals....
Yep, I want the lens...and I want it to work, and I'll wait a while before trying again...
When I had my experience (before Christmas), Canon service had little experience with this lens. I suspect this will change quickly.
Gary, I'm afraid I'm going to have to ask you to refrain from posting within an hour of my posts, or moondigger is going to claim I'm you, in addition to being myself and Bill Ruckman.
Good job, Gary. Thanks for describing your efforts. I'll stay tuned for further details, and may jump in and get one in a few months, if i hear promising news.
RoyPertchi wrote:
As I thought, Sam. I think a tech would be delighted to learn explicitly that a bunch of serious users on this board have identified a close focusing problem with this lens, under three feet. If I had one, I would make every effort to reach a tech, just to talk it over.
Already been in contact with C-USA, and it had made it's way through the chain, to the right people as well. I even supplied them this thread. I will keep any interested people posted. Gary is already on my list as anyone else who has asked me to include them.
By the way all....the lens did the same on both my bodies...and I sent my 1Ds2 in on the last calibration trip to Canon...No problem found with the body.
Net result of all the efforts? Backfocusing fixed at short distances...but front focusing induced at large distances....
Eh, I'm fine at this point. I have much bigger fish to fry - straightening out my onsite printing vs. office printing workflow is much more important. The worst that happens is that I get my money back, and I keep using the 50/1.4. I would rather use the 50/1.2, but saving $1,200 and getting photos that are 90% as good isn't a terrible position to be in. I would have more faith in the L serving me well for years to come, but it isn't the end of the world if I have to wait a few months for Canon to get its act together.
So, bad news. Went over to my dealer who has another 50/1.2L on the shelf. It shows the same exact issue, while my 50/1.4 continues to focus as expected. Didn't try all the lenses on another body, but the positive 50/1.4 test seems to indicate its not a body-related issue.
The lens will be going back to Canon for another round of "fixing". If it comes back screwed up again (as I suspect it will) then I will just get my money back and wait for an official announcement from Canon that the issue with the line has been resolved.
EDIT: The newly tested lens has a UU1200 date code.
Just kidding... I have done extensive close focus testing with this lens. Mine was not back-focusing on my 5D but the DOF was asymmetric around the target. IOW, there was alot more in focus behind the target than in front. BUT the target was still in good focus. 
It just seems like the overwhelming evidence here is that the lens backfocuses stopped down. I do still have the lens, but I don't see why I would use an off-center point to test with. What would that tell me, really?
?
