Should i send my 50L in?

Which you describe sounds similar to my 50L. I will preface my response by saying it is only subjects that are far away (10ft+) that I notice the issue.

I MFA'd mine at 25 X the FL. This gave me a MFA of -15. I've MFA'd several lenses and the 50L was by far the trickiest. Wide-open against a scale at an 45 degree incline, it is very difficult to ascertain the correct focus. Here's what I did:

Use a scale/ruler (you can find them online to print) that is black and white. Manually focus at 0 (I use a little checkerboard image affixed to a piece of cardboard at the 0 marker. Manually focus on that. Use the CA (it will appear as green and red ghosting against the markings on your scale). Note what the CA looks like after you've manually focused at 0. Now AF and MFA until you match what your. mF'd image looks like. This gave me -15.

Now, for subjects I would normally shoot at a 50mm FL, my AF is bang on every time, even at f/1.2 focused on someone's near eye. Every time.

Yes, subjects. that are further away will be OOF. I suspect this is a character/defect of the lens design. If it bothers you, get rid of the lens. Otherwise, simply manually focus. Because the framing/composition is usually awkward at such a distance with 50mm, It doesn't bother me one bit. This is easily overcame by MF'ing anyway. MF on the 50L is an absolute joy, embrace it.

Thanks for the tips guys, Right now -24 for Closeup Portrait work is perfect, and it seems that default 0 is perfect for everything else, Just have to figure out a middle ground for mid range shots. It's annoying having to do it but with Magic Lantern Quick Menu, I can easily change it in 2 seconds. I am still going to do another MFA adjustment tonight and see how it goes. Ill try out the ruler thingy.

Here are some examples (Sorry for the Quality), Top is default 0, Bottom is -24. Focused on her Right eye both times.

what aperture? what distance?

You realize that it's extremely common for the 50L to back focus. You wont back focus at f/1.2 but if you stop down even upto f/4 and shoot your subject 5 feet away......typical 50L backfocus!!!

Thats the nature of the beast!!

AlanU wrote in post #17010425
what aperture? what distance?

You realize that it's extremely common for the 50L to back focus. You wont back focus at f/1.2 but if you stop down even upto f/4 and shoot your subject 5 feet away......typical 50L backfocus!!!

That's the nature of the beast!!

Well yeah if i'm shooting a portrait at f8, i will most likely leave it at 0, but I don't really experience Back Focusing with the 50L however with -24, I manage to get almost all my shots in focus at f1.2 - f2. It really does work wonders. Above shot was at f2.5.

If you micro adjust at f/1.2 you should get somewhat accurate photos as long as your lens/camera cal is not severely out. Try shooting the same photo with f/2 to f/4 ...5 feet away from your subject. You'll very likely have some severe backfocus.

At f/8 alot of zooms can produce similar results for portrait work.

I am not a fan of Sigma at all. However if the ART series 50mm is accurate (holding my breathe) I'd buy that in a heartbeat compared to a 50L. I've tested way too many 50L's with no love.

-24 is seriously bad. You'll probably find the lens to be all over the map as you change camera/subject distances.

I used a 50L for a while and I couldn't tolerate the "what if I am at this distance? what about this distance?" I was more concerned about technical issues rather than getting into the "groove".

Reset your MFA settings, what your experiencing is focus shift, not MFA issues. Read up on it, the 50L is a well known focus shifter and not a tool for the faint of heart.

Charlie wrote in post #17011078
Reset your MFA settings, what your experiencing is focus shift, not MFA issues. Read up on it, the 50L is a well known focus shifter and not a tool for the faint of heart.

I used to parrot this information too, but then I noticed that my 50L didn't seem to ever be missing shots at 'close range' when shooting f/2 - f/2.8.

I looked into it a bit. The focus shift is a very small effect, and is generally only is enough to be detected in the range of MFD to about 2X the MFD. That's not a distance (1.5 to 3 feet) where I'm using a fast lens at such a large aperture.

To me the OP's problem looks like a calibration issue. I think the lens is off at one end of the range and not the other, and so a trip to Canon is what is needed. I once had a 135L that did the same thing. It was bang on accurate at close range but backfocused like mad at long range.

That was before MFA was invented, but it didn't matter because MFA would not have fixed the problem. Canon service fixed the problem.

JeffreyG wrote in post #17011148
I used to parrot this information too, but then I noticed that my 50L didn't seem to ever be missing shots at 'close range' when shooting f/2 - f/2.8.

I looked into it a bit. The focus shift is a very small effect, and is generally only is enough to be detected in the range of MFD to about 2X the MFD. That's not a distance (1.5 to 3 feet) where I'm using a fast lens at such a large aperture.

To me the OP's problem looks like a calibration issue. I think the lens is off at one end of the range and not the other, and so a trip to Canon is what is needed. I once had a 135L that did the same thing. It was bang on accurate at close range but backfocused like mad at long range.

That was before MFA was invented, but it didn't matter because MFA would not have fixed the problem. Canon service fixed the problem.

TS's eye shots look to be in that range, shot at 2.5. His first shot would have been the AF point. Outer 6D point, backlit = bound for trouble.

edit: either way, does not look like a good way to test MFA.

Charlie wrote in post #17011078
Reset your MFA settings, what your experiencing is focus shift, not MFA issues. Read up on it, the 50L is a well known focus shifter and not a tool for the faint of heart.

The OP also claims he has the same issue with his 135 L and also states he returned a 50 mm 1.4 with focus problems. I agree with JeffreyG that it probably should go to Canon service for a definitive answer because it sure doesn't look like its a simple fix at this point.

Charlie wrote in post #17011157
TS's eye shots look to be in that range, shot at 2.5. His first shot would have been the AF point. Outer 6D point, backlit = bound for trouble.

edit: either way, does not look like a good way to test MFA.

You have to keep it in perspective. Here is a link to a typical article describing the issue. Note that when you read this, the author seems very disappointed in the lens.

http://www.martinbaile​yphotography.com …-lens-dynamic-back-focus/

Then if you really look at the material presented, he is showing a 6mm shift in focus by f/4 when using the lens at a focus distance of 50 cm.

Think about that.....somehow the internet turned a phenomenon of a 6mm focus shift at 50 cm into something that can explain a lens missing focus by 5-10 cm when focused at 5-6 feet! I even believed it for a long time, until it occurred to me that I'd never actually experienced a focus shift problem with my own 50L.

It turns out I just do not use the lens at f/2-f/2.8 at ranges below 3 feet, and a suspect not many other people do as well. At 5-6 feet the shift cannot be detected by the most careful of testing.

Jeff,

The 50L is a quirky beast. I've tested many copies even after the alleged "quiet" fix canon has done..I still think copy variations is extremely high.

I just am concerned that there should be no limitations in what aperture you use regardless of distance. Practice will let people figure out the lens. In my case I'd sometimes need to shoot anything between f/1.2 to f/4 depending on subject matter. Even my fragile canon 50 f/1.4 has never failed me in focus shift.

I shouldn't talk....I really dislike the 50mm focal length for my style of shooting

However the focus shift issue for me is real and not acceptable for me. I gave up on the 50L. I'm even going to test the sigma art 50mm just to entertain the thought of a decent 50mm in Canon land. I find my m43 Olympus OMD em5 with panny/leica 25mm f/1.4 (50mm equiv) great in IQ compared to my Canon 50 f/1.4.

I've honestly now forgotten how many 50L's i've tested with significant focus shift. ...Canon should have invested in major R&D in a 50Lmk2 rather than other new lenses they've introduced recently. Canon knows everyone is yearning for a newer 50L update (my assumption anyways).

The Ops issue certainly sounds like a serious calibration issue. I absolutely hated my 1dmk3 even when the af issues were fixed. My 35L, 100L were out by miles with the camera calibration. Sounds like his camera is doing the same thing.

I dunno, I notice very similar behavior with my 50L, and none of the other lenses I've had on my 6D needed any MFA. I absolutely believe it is the nature of the lens.

I would MFA at the distance you're going to normally shoot at. For me that was closer, and was a -15. For far away things, meh, I can MF in a pinch. Otherwise, works beautifully.

It really seems to come down to individual preference with the 50L. Some people will detest its quirkiness, other will embrace it. If it really bothers you, don't keep it.

hiketheplanet wrote in post #17011256
I dunno, I notice very similar behavior with my 50L, and none of the other lenses I've had on my 6D needed any MFA. I absolutely believe it is the nature of the lens.

I would MFA at the distance you're going to normally shoot at. For me that was closer, and was a -15. For far away things, meh, I can MF in a pinch. Otherwise, works beautifully.

It really seems to come down to individual preference with the 50L. Some people will detest its quirkiness, other will embrace it. If it really bothers you, don't keep it.

I agree. If your hired for an event and are not a master of taming the quirkiness your going to have extremely unhappy clients.

If you print that'll save you...however many pixel peep and appreciate composition on a computer monitor aswell.....

-15 MA is totally unacceptable for me. If you have to do that you'll probably find subject/camera distance will be all over the map.

AlanU wrote in post #17011248
I just am concerned that there should be no limitations in what aperture you use regardless of distance. Practice will let people figure out the lens. In my case I'd sometimes need to shoot anything between f/1.2 to f/4 depending on subject matter. Even my fragile canon 50 f/1.4 has never failed me in focus shift.

My 50/1.4 failed me in getting in focus in low light all the time, but my 50L has never failed me with focus shift.

My problem is that the 50L now has such an undeserved reputation relative to the focus shift that people cannot even get reasonable advice on the lens.

OP - "My lens seems to have a focus calibration issue."

Internet "Oh, it's the 50L, they all do that and it cannot be fixed. Sell it or throw it away."

Totally wrong. The OP's problem sure as heck doesn't look like focus shift to me. It looks like a lens (or body) that needs a calibration at Canon service. I'd send them in together.

As for the 50L itself, go ahead and Google the shift issue, and once you get away from the armchair quarterbacks take a look at the people who have actually tested for the phenomenon. It's not a "5-6 foot range' issue, it's a '1.5-3 foot' range issue.

I wonder how many people have gotten a 50L with calibration issues that they dismissed as being focus shift? I have a 50L that works well, but I also had one before that did not work well. But the problem with it was not focus shift.

Elton Balch wrote in post #17011163
The OP also claims he has the same issue with his 135 L and also states he returned a 50 mm 1.4 with focus problems. I agree with JeffreyG that it probably should go to Canon service for a definitive answer because it sure doesn't look like its a simple fix at this point.

I'm convinced it's a weak outer focus point issue

and as for the reason I'm saying it's focus shift for the eye shot, is because it looks to be close to MFA, otherwise the F2.5 DOF would have covered both eyes. It's also a horrible way to test for MFA at such close distances. A shakey hand and/or slight swaying motion by user/subject can change the focus spot in a split second when DOF is that thin.