50 mm f1.2 focus shift issue

Just curious if anyone was still experiencing issues with their 50mm 1.2s ?

as this post touched a bit on it, there are plenty out there with the same deal.https://photography-on-the.net/forum/showthre​ad.php?t=371097

All 50L has focus shift. It's a design problem. The question is to find one that shift within or close to dof limit for given apperture. Or learn to shoot around it's limitation.

I do.

I sent it to canon for repair under warranty.

I got it back today and this is what they said:

Service Details

"Your product has been examined and it was found that the adjustment of the circuit board was incorrect causing the auto focus to operate improperly. Electrical adjustments were carried out on the circuit board and product functions were confirmed. Other electrical adjustments, inspections and cleaning and mechanical adjustments were carried out."

It still back focuses at least a centimeter between f/2 and beyond (narrower) with the center focus point... and with the top focus point. At all other focus points, it seems to work fine. At f/1.2, it is spot on every time.

I didn't realize my copy had this issue, as I spent most of the first month shooting at f/1.2. I noticed this problem after doing a shoot with a friend at f/4 and got backfocus the entire time. So I printed out a test chart, shot at a 45 degree angle from the side, and voila, it's there. No, I don't have a tripod, but I got the same results after hundreds of shots and dozens of different test subjects.

I'm either going to sell this lens (I dunno what for, the Sigmalux? I heard it has front focus at close distances and backfocus at far distances) or settle with just not using the center focus point within that aperture at all.

Some people claim to have perfect working copies, especially the more recent purchases (one I remember was from Adorama), so I guess it is possible.

Mine was manufactured in late November 2009, and I got it from Abe's of Maine.

Oh well, the saga continues...

It's like Toyota selling a car where you can't go between 20-50mph with more than one person in it.

What Canon should do is if and when a Mark II comes out, they should give us all rebates so we can trade our faulty Mark I versions in for the Mark IIs (and pay the price difference, of course) on top of a 10% discount for the lens or future purchases. It's the least they could do so we don't have to go through all the hassle of trying to sell it on our own and not getting much in return.

Focal shift results from uncorrected spherical aberrations and it's not a fault. It's there on the 50L (and to a lesser extent, the 85L) to aid in the rendition of superior bokeh. It's a bit unfortunate that certain copies of the 50L exhibit more shift than others, but that's just the way it is. I'd also love to have a 50L II where something was done, such as the inclusion of an aspherical element, but it's very important to note that the focus shift on the 50L is very much there by design.

You can circumvent the focus shift by using outer AF points as well.

toxic wrote in post #9551244
You can circumvent the focus shift by using outer AF points as well.

I've heard this is the case for some.
Interestingly enough, for me, the lens performs better in AI Servo mode. Go figure...

AlexMoPhotography wrote in post #9550669
I'm either going to sell this lens (I dunno what for, the Sigmalux? I heard it has front focus at close distances and backfocus at far distances) or settle with just not using the center focus point within that aperture at all.

Some people claim to have perfect working copies, especially the more recent purchases (one I remember was from Adorama), so I guess it is possible.

Mine was manufactured in late November 2009, and I got it from Abe's of Maine.

Oh well, the saga continues...

As someone stated, it's in the design, all copies have it, some more, some less, like Nick said, AI servo works for some, outer points work for some, but if you just want to use the 50L like any other lens you own...and you use it in a specific manor, you're out of luck...I went through 3....I love the lens but I shoot in the "danger zone" most all the time with my 50mm's.....So I grabbed a Sigma "lux"....Both I've owned didn't front or backfocus close or far....just had a slight micro adjust at all distances...Sent it in to Sigma, they fixed it and I've been happy ever since....The build is not as luxurious as the L, but it just works...That's all I want....You'd be pretty hard pressed to tell the difference between the images (L vs. EX) and the bokeh from the Lux is unmatched by any 50mm I've used......
If and when Canon does put out a "fixed" mkII, I'll be the first in line.....I just prefer the Canon USM and build...In the mean time the EX is a perfect workaround..
Good luck

Sorry to say there is a flaw in the design. Only those whom are die hard fans of the lens would deny it.

Collin85 wrote in post #9550832
I'd also love to have a 50L II where something was done, such as the inclusion of an aspherical element

The 50L has an aspherical element, that's not the problem. What's missing form the design is a rear floating group which is usually employed for close focus correction and can also help compensating for focus shift.

The 85L has it, the 35L has it. I'm sure Canon did not just forget to add one to the 50L, but it sure shows if you're shooting close up wide open that it's not there.

WICKEN wrote in post #9551590
Sorry to say there is a flaw in the design. Only those whom are die hard fans of the lens would deny it.

Well, that flaw provides optical characteristics that very few other fast 50's can match. And it introduces problems that other fast 50's don't have. You can call it a flaw, sure, but I felt the same way about the nisen bokeh from the 50/1.4 and therefore hated it with a vengeance.

I feel sorry for the early adopters and those trusting souls that buy a 50L thinking it's going to be as instantly gratifying as most of the other L primes. It's not. But if you know the 50L's shortcomings and your shooting style allows working around them, they are not as much of an issue as some would have you believe.

Craftsman, know your tools.

zara wrote in post #9551634
Well, that flaw provides optical characteristics that very few other fast 50's can match. And it introduces problems that other fast 50's don't have. You can call it a flaw, sure, but I felt the same way about the nisen bokeh from the 50/1.4 and therefore hated it with a vengeance.

I feel sorry for the early adopters and those trusting souls that buy a 50L thinking it's going to be as instantly gratifying as most of the other L primes. It's not. But if you know the 50L's shortcomings and your shooting style allows working around them, they are not as much of an issue as some would have you believe.

Craftsman, know your tools.

I agree.

Collin85 wrote in post #9550832
Focal shift results from uncorrected spherical aberrations and it's not a fault. It's there on the 50L (and to a lesser extent, the 85L) to aid in the rendition of superior bokeh. It's a bit unfortunate that certain copies of the 50L exhibit more shift than others, but that's just the way it is. I'd also love to have a 50L II where something was done, such as the inclusion of an aspherical element, but it's very important to note that the focus shift on the 50L is very much there by design.

toxic wrote in post #9551244
You can circumvent the focus shift by using outer AF points as well.

nicksan wrote in post #9551453
I've heard this is the case for some.
Interestingly enough, for me, the lens performs better in AI Servo mode. Go figure...

WICKEN wrote in post #9551590
Sorry to say there is a flaw in the design. Only those whom are die hard fans of the lens would deny it.

zara wrote in post #9551605
The 50L has an aspherical element, that's not the problem. What's missing form the design is a rear floating group which is usually employed for close focus correction and can also help compensating for focus shift.

The 85L has it, the 35L has it. I'm sure Canon did not just forget to add one to the 50L, but it sure shows if you're shooting close up wide open that it's not there.

I have heard of the focus shift so many times and yet have no clue of what it actually means?

Anyone want to pretend I am a 2 year old?...

zara wrote in post #9551605
The 50L has an aspherical element, that's not the problem. What's missing form the design is a rear floating group which is usually employed for close focus correction and can also help compensating for focus shift.

Thanks for that.

mikeassk wrote in post #9552213
I have heard of the focus shift so many times and yet have no clue of what it actually means?

Anyone want to pretend I am a 2 year old?...

A focus-shifting lens essentially back-focuses as the aperture is stopped down. There's no shift wide-open, but it gets progressively worse as you stop down more and more. However it's important to note that as the aperture is closed, the DoF increases, so there's naturally a "sweet spot" f/stop when the back-focus does the most detriment to your photograph.

I've never owned a 50L, but I once had a focus-shifting 16-35L and it was the worst at f/5.6. Larger than f/4, the shift was minor enough so that the subject was still within the DoF. On the other hand, anything smaller than f/8 meant the DoF increased enough so that the back-focus was negated. Of course, all of this depends on the distance too, which motivated the terminology "danger zone" (that specifies the range of apertures and distances to avoid using).

Can you AF with the DoF preview button held down?