RoyPertchi wrote:
Sam, the implication of your reasoning is that William's and other's measurments of a dip in sharpness of the 50 1.2 can be attributed to the AF error phenomenon, and therefor the dip in sharpness of the 1.2 lens should be recanted until the AF issue is resolved. To your knowledge, has William so recanted his test results?
Roy, I and others have questioned whether this phenomenon may have played a role inadvertantly with those results since we first found this issue. As far as I know, WC's assessment still stands and has yet to be recanted, even though William has been an integral part in the backfocusing discussions. I believe he mentioned was going to be shooting an event, then posting back results, however has not as of yet.
For the most part I'm experiencing the same results as Radiohead. However still, a trusted member of this forum has agreed to have a second look at my lens. A pair of objective eyes if you will. He'll run it through his own set of paces and confirm or deny if my lens does or does not have a focusing issue. For the record, I wouldn't normally do this, but the number of complaints here has raised concern on my part. Though I've tried to duplicate what others are experiencing, my lens seems to work just fine. Since the start of this thread, I have begun to question whether a few of my misfocused shots were user error or indeed backfocusing. Hopefully this issue will be put to rest for me once and for all. I'll keep you all posted.
if it seems to work fine, after all of this ridiculous pixel peeping, why don't you just use it? If there were a problem you wouldn't need second and third opinions.
Too add, I have shot charts, batteries, real people, no people, near, far, wide open, stopped down, horizontal, vertical, tripod, no tripod, auto, manual, center focus, off center focus, one shot, AI servo...
Everything looks good. If anything, for a piece of mind.
John Shultz wrote:
if it seems to work fine, after all of this ridiculous pixel peeping, why don't you just use it? If there were a problem you wouldn't need second and third opinions.
Why not? You can go not too far back in this thread and see that I was one of those who stated I didn't have a problem to begin with. But some of those who claimed to not have any problems at the beginning are now saying they are noticing focusing issues. Maybe I've missed something. Maybe mine has this "inherent" problem and I just haven't seen it yet. Maybe I should heed that quote in my own signature! lol Whatever the case, if it'll help me sleep better at night....
In my opinion the back focus shown on the above two tests is so slight as to be insignificant in regular use. I dont doubt that there are worse performers out there than the above two. This "asymmetry" of DOF is very similar to what Iam seeing with my lens when I create an unrealistic test scenario similar to the above two. The lens does not back-focus enough for the target to be OOF. Its just the DOF is shifted in backward. I did notice an improvement in DOF symmetry when I switch from the center point to other minor points on my 5D. This leads me to wonder if there is not a minor error in the focusing algorithim for the center point only. The problem seems minor and has not adversly affected my "real world" shooting with the lens. I plan to keep and continue to enjoy the lens. I have to admit though the testing and playing around has been fun....
RoyPertchi wrote:
Sam, the implication of your reasoning is that William's and other's measurments of a dip in sharpness of the 50 1.2 can be attributed to the AF error phenomenon, and therefor the dip in sharpness of the 1.2 lens should be recanted until the AF issue is resolved. To your knowledge, has William so recanted his test results?
No, he hasn't. But he has admitted that his lens appears to be suffering from the same issue. I think his rationale right now is that he was using Manual Focus for the tests, and at a greater distance but as I've shown the same issue is there if you're using the Camera-assisted Manual Focus.
Hopefully he'll rejoin this thread at some point to expand or correct what I've said.
mbailey wrote:
In my opinion the back focus shown on the above two tests is so slight as to be insignificant in regular use. I dont doubt that there are worse performers out there than the above two. This "asymmetry" of DOF is very similar to what Iam seeing with my lens when I create an unrealistic test scenario similar to the above two. The lens does not back-focus enough for the target to be OOF. Its just the DOF is shifted in backward. I did notice an improvement in DOF symmetry when I switch from the center point to other minor points on my 5D. This leads me to wonder if there is not a minor error in the focusing algorithim for the center point only. The problem seems minor and has not adversly affected my "real world" shooting with the lens. I plan to keep and continue to enjoy the lens. I have to admit though the testing and playing around has been fun.......Show more →
Whose results are you referring to? If you're referring to mine, I obviously completely disagree. The only reason why I'm doing the chart-type tests is because I was turning up a lot of OOF tests in practical shots. My shots are not displaying "DoF shift", they're out of focus, plain and simple - this would be much more apparent if I wasn't sharpening the test photos. This is something that shows clearly in portraiture - focusing on eyes leads to ears being in focus, focus on one eye leads to the other eye being in focus (or neither eye in focus). It's totally unacceptable, especially in a $1,600 lens where the $300 lens focuses perfectly. Anyone who says otherwise is fooling themselves.
Edited by Sam Bennett on Feb 07, 2007 at 08:30 AM GMT
Just received a shipment from B&H containing a 50 1.2. Haven't had a chance to try it out, and won't until tonight or tomorrow, but the date code is UV0101, serial 730XXX.
Mine was back focusing as well and in the real world shots it was worse as sometimes it backfocus as much as an inch or two. I returned mine and my dealer retuned the same results as I did. Totally inconsistant. I am not getting one till Canon fix the problem
FWIW, my lens is on its way to Canon again - this time through my local dealer that I originally bought it from. The ticket specifically states focusing within 3ft this time, so we'll see what happens. I don't really have any faith that Canon will be able to fix it, but since I have the 50/1.4 its not too big of a deal to be without it while it takes the extra trip. Cross your fingers.
At 1.2, you should expect to miss focus on many or even most of your shots. Also, the actual focus will mostly likely be on the highest contrast area in the vicinity of the selected focus point.
dcmiller wrote:
At 1.2, you should expect to miss focus on many or even most of your shots. Also, the actual focus will mostly likely be on the highest contrast area in the vicinity of the selected focus point.
i never expect any lens to misfocus in any number of my shots, regardless of aperture. my 35L locks focus wide open at any distance, especially close up. i've had 85Ls that have locked focus wide open at minimum focusing distance. all three copies of the 50L that i had misfocused consistently at 1.5' to 3' distances, right where i had planned to use it at least 50% of the time.
this is an issue. we have proven it multiple times over. i see no reason to "expect [this lens] to miss focus on many or even most of [our] shots" whatsoever. i have wider and longer AF lenses with equally shallow DOF that have zero issues locking proper focus wide open. i will not accept a 50L that can't perform the same and i highly doubt anyone else will, either.
dcmiller wrote:
At 1.2, you should expect to miss focus on many or even most of your shots. Also, the actual focus will mostly likely be on the highest contrast area in the vicinity of the selected focus point.
Read the last dozen or so pages of the thread. The issue people are reporting is that at f/1.2 focus is perfect and it gets worse as you stop down. Specifically, past f/2 at close distances the lens backfocuses pretty badly.
dcmiller wrote:
At 1.2, you should expect to miss focus on many or even most of your shots. Also, the actual focus will mostly likely be on the highest contrast area in the vicinity of the selected focus point.
My initial thoughts were along the same lines. That is until reports were coming in that the back-focusing was apparent (sometimes worse?) even when stopped down. I really would like to see more screen shots showing what AF point these guys are using (when viewed with ZoomBrowser EX) when performing these tests or shooting real world subjects.
I give the benefit of the doubt to the guys reporting these problems. I'm assuming most of these photographers know what they're doing.
OK, so I got my copy today and quickly tried it out tonight on my desk at home focusing on a number of highly definable items at 1.2, 1.8 and 3.2 and it was dead on. Used the center focus point on a 1DsII at roughly 2 feet from the subject............
lord_malone wrote:
I really would like to see more screen shots showing what AF point these guys are using (when viewed with ZoomBrowser EX) when performing these tests or shooting real world subjects.
I'm not really sure what it would show you. I've tried it with the center point and off-center points on the 1D MKII, the center point of the XT I recently sold, and at the camera store this afternoon with an XTi they had sitting in a case. The result is the same every time. And shooting with the 50/1.4 is identical settings yields "perfect" focusing. Every time I do this test I shoot multiple shots -- between 3 and 5. Focus, take the photo, de-focus and re-focus, take another, etc. With this problem, the lens will literally never focus accurately. It's not like, one photo is in focus, the next is not... they're all out of focus.
I'm no stranger to fast glass. I shoot primarily with primes, usually wide open. This is both with static subjects and fast moving sports subjects. I know how to pick good focus points and what will give AF systems the heebie jeebies. My lens is simply not working the way it should.
If you're trying your lens in similar conditions and you're unclear on whether it's happening or not, then I would guess that it is not. It is an extremely obvious issue. Consider yourself lucky.
