50L AF accuracy on 5Dc vs 7D

I recently picked up a 50L... and after trying it out on my 5Dc and 7D, I've noticed that I get significantly less keepers with my 5Dc. Depending on my spot positioning, it'll either back or forward-focus with alarming consistency. The results are repeatable at f/1.2, given the same distance and object. With my 7D, however, I'm seeing focus accuracy 8 to 9 out of 10 tries. The lens isn't out of calibration, and in short-range (1-3 feet) tests with charts, I'm getting spot-on results. My 5Dc operates just fine with my other lenses...

Even with spot, these results are most prevalent while focused on smaller objects. The results are leading me to believe that when focused on objects that fill less of the frame... the lens is actually focusing on the surrounding background or foreground.

Depending on the situation, I'd say half of my varied shots (on the 5Dc only) come out either back/front focused. Has anyone with a 5Dc and 50L seen these types of results?

I had focus shift problem with my 50L. It was unacceptable with my 5D but somewhat OK with my 1D3. This was during testing in the danger zone using single-shot AF with the centre AF frame. However, in my experience, using AI-Servo focus on 5D solved most of the problem. Other people say they have also experienced this. They say using non-centre AF frames also works well which I haven't tried.

Later on I tried AF microadjust to balance the focus shift effect. I did this with 1D3, 5D2 and 7D and the result has been excellent.

So in summary, try AF microadjust to nail the AF down on your 7D and to increase your keeper rate with 5D, try AI-servo focus or perpheral AF frames. Hope it works out.

MOkoFOko wrote in post #12530951
I recently picked up a 50L... and after trying it out on my 5Dc and 7D, I've noticed that I get significantly less keepers with my 5Dc. Depending on my spot positioning, it'll either back or forward-focus with alarming consistency. The results are repeatable at f/1.2, given the same distance and object. With my 7D, however, I'm seeing focus accuracy 8 to 9 out of 10 tries. The lens isn't out of calibration, and in short-range (1-3 feet) tests with charts, I'm getting spot-on results. My 5Dc operates just fine with my other lenses...

Even with spot, these results are most prevalent while focused on smaller objects. The results are leading me to believe that when focused on objects that fill less of the frame... the lens is actually focusing on the surrounding background or foreground.

Depending on the situation, I'd say half of my varied shots (on the 5Dc only) come out either back/front focused. Has anyone with a 5Dc and 50L seen these types of results?

I have picked up a 5Dc few weeks back and couldn't be more happier to glue on to 50L. Tried on my friend's 5Dc and love it so much that drives me to buy a 5Dc.... All shots are wide open and tack sharp with magics on 50L wide open.

50L is flaw against MFD, keep yourself working distance of minimum and the magic f1.2L surprises you.....!

actprivate wrote in post #12532008
I had focus shift problem with my 50L. It was unacceptable with my 5D but somewhat OK with my 1D3. This was during testing in the danger zone using single-shot AF with the centre AF frame. However, in my experience, using AI-Servo focus on 5D solved most of the problem. Other people say they have also experienced this. They say using non-centre AF frames also works well which I haven't tried.

Later on I tried AF microadjust to balance the focus shift effect. I did this with 1D3, 5D2 and 7D and the result has been excellent.

So in summary, try AF microadjust to nail the AF down on your 7D and to increase your keeper rate with 5D, try AI-servo focus or perpheral AF frames. Hope it works out.

Well, gave it a go--I tried the other 8 focus points, with pretty much the same result. AI Servo is another matter, sometimes giving me proper shots. With the near-constant hunting, I'm bound to get maybe 1 out of 3 when I'm in high-speed continuous shooting. Oh, how I miss the 5d2's live view mode and MA feature.

The 50L doesn't seem to need any MA on my 7d--it's pretty darn accurate. I may just have to keep the 50L on my 7d.

imperian wrote in post #12532603
I have picked up a 5Dc few weeks back and couldn't be more happier to glue on to 50L. Tried on my friend's 5Dc and love it so much that drives me to buy a 5Dc.... All shots are wide open and tack sharp with magics on 50L wide open.

50L is flaw against MFD, keep yourself working distance of minimum and the magic f1.2L surprises you.....!

I've seen numerous complaints about focus accuracy of 50L's, so I know it's not just me. A lens of this price shouldn't be dedicated to short-range shooting. If this can't focus properly on an object only 5-7 feet away, it's all but useless, good bokeh or not.

MOkoFOko wrote in post #12532904
I've seen numerous complaints about focus accuracy of 50L's, so I know it's not just me. A lens of this price shouldn't be dedicated to short-range shooting. If this can't focus properly on an object only 5-7 feet away, it's all but useless, good bokeh or not.

All lens has it's own dedicated style of shot and I can't understand why everyone is shooting 50L near MFD. It doesn't mean for that. You may go with dedicated Macro or 24L (hell of a bokehlicious)......

I am still extremely happy with my 50L on 5Dc....

Huh ? cuz somebody wants to.

imperian wrote in post #12534226
All lens has it's own dedicated style of shot and I can't understand why everyone is shooting 50L near MFD. It doesn't mean for that. You may go with dedicated Macro or 24L (hell of a bokehlicious)......

I am still extremely happy with my 50L on 5Dc....

I don't think it's the lens as much as it is the 5D body. The depth of field is paper thin at 1.2. It's a challenge just to keep ones body movement within the DOF. The 50L require lots of practice to get the most out of it.

imperian wrote in post #12534226
All lens has it's own dedicated style of shot and I can't understand why everyone is shooting 50L near MFD. It doesn't mean for that. You may go with dedicated Macro or 24L (hell of a bokehlicious)......

I am still extremely happy with my 50L on 5Dc....

If it doesn't mean for that, they need to increase the MFD...

Could the accuracy differences be related to narrower DOF on the FF body? I mean, maybe it is often just as off on the 7D, but the DOF is deeper enough to hide it?

tkbslc wrote in post #12535597
Could the accuracy differences be related to narrower DOF on the FF body? I mean, maybe it is often just as off on the 7D, but the DOF is deeper enough to hide it?

Crop bodies do just that, crop away the dof. If two cameras are shot at the same distance from the subject they'll have the same amount of dof or bokeh but the full frame will show almost 2 times as much of it(making it look like it has quite a bit shallower dof than if you backed up with the 7d to get that same framing). If your image is in focus then it's in focus...Sensor size is irrelevant.

However, it could be that he does have to go closer to the subject with the 5d to get the same framing as with the 7d. Since the issue seems to be near the MFD, he could be more likely to shoot at mfd with FF.

It could also help that the 7d has the micro adjustment feature to fix some slight front or back focusing, as well as simply a more advanced AF system.

You are right, but in real world use, people don't use a 50mm the same on both cameras since one becomes a short telephoto.

Could this be the BODY + LENS COMBO?
Like 85L II is hit and miss in 5D II or 7D, but some people report it always hit on 1D series.
OR 24L II is hit and miss with 5D II, but it is okay with the other bodies.

Could this be the problem?

KY707 wrote in post #12539022
Could this be the BODY + LENS COMBO?
Like 85L II is hit and miss in 5D II or 7D, but some people report it always hit on 1D series.
OR 24L II is hit and miss with 5D II, but it is okay with the other bodies.

Could this be the problem?

Not really, at least for me. I have tried my 50L on 2 5Dc's, tack sharp at 1.2 without any need of calibration. Perhaps is the DOF is too shallow to handle.

I have never shoot anything less than 5 ft, use it extensively on full budy portrait where it need distuingsh BG isolation.