Can someone explain the Canon 50mmL f/1.2 "backfocus problem" ?

[cayenne]

Thank you all for the fantastic information.
I think I understand most of it, but am taking to task to research more based on what I see here.

I'm planning to get two lenses here in the near future.

I'm going to first, get the 70-200 f/2.8 L IS USM II.

I think I'm going to put the 50L on my list for the next one...

I've been following on Creative Live this week, the talks by Sal Cincotta, with his excellent lectures all week on Wedding Photography, and been watching him use the 50L quite a bit, and the resulting pics he's been taking with it...well, some of them are stunning.

So, I'm going to make this my next prime. I need the zoom tele first (he also was shooting with the 70-200L a lot too)....and the next prime will be the 50L.

One question...is there rumor of a new version of the 50L in the works?  I'm coming to the understanding that the current design, is getting a bit old....so, wondering if there is a new one coming out in the relatively near future?

Again, thank you all for the excellent information.

If anyone has real world reviews based on their ownership and use of the 50L, please, keep adding them onto this thread...very interesting reading, especially any methods or means you use to work around the focusing issues....

C

[neuroanatomist]

One question...is there rumor of a new version of the 50L in the works?  I'm coming to the understanding that the current design, is getting a bit old....so, wondering if there is a new one coming out in the relatively near future?

It's a 2007 lens, which is relatively quite recent.  I would not expect an update anytime soon...

[Mt Spokane Photography]

One question...is there rumor of a new version of the 50L in the works?  I'm coming to the understanding that the current design, is getting a bit old....so, wondering if there is a new one coming out in the relatively near future?

It's a 2007 lens, which is relatively quite recent.  I would not expect an update anytime soon...

+1  "A bit old" means ~20 years for "L" lenses.  Development and tooling costs for a upgraded lens is very high, so we only see new versions more frequently for the high volume lenses where the tooling can be paid for in a reasonable time.  The big whites were upgraded after 10 years, but the high cost of the re- tooling which is recovered over a relatively small number of units, was added to the price.  This creates a bit of a sticker shock.

[Daniel Flather]

If anyone has real world reviews based on their ownership and use of the 50L, please, keep adding them onto this thread...very interesting reading, especially any methods or means you use to work around the focusing issues....

C

Not much too add, but the 50L is a joy to mount and use.  I don't know what body you have, but it seems to be the perfect mate to the 5D3.  It's the right size and weight.  I never stop the lens down, so I right any focus errors to the thin DOF and user error.  I don't know why, but with all my lenses, the 50L is the only one in which never use the hood. 

[CharlieB]

The sad part.. is Canon could - if they wanted to - program the lens to compensate for any focus shift, based on focus distance and aperture used.  Thats something Leica cannot do with their excellent Noctilux...  the latter being very persnickety about the positioning of its aperture blades depending on the exact focal length of the lens thats produced - which may vary by some fraction of a mm up to nearly a full mm in focal length.  They've gone so far as to use one of several helix pitches, depending on the optics of the particular lens.  All that is mechanical.  Canon could do it easily in lens firmware... the data flow both ways is there already, they just need to make it happen.

[mrsfotografie]

Interestingly yesterday I ran into this 'focus shift' issue as well... on my Samyang 14 mm when I put an AF confirm chip in and went to micro-adjust the AF, only to find that when I calibrated it for f/2.8, all shots at smaller apertures (f/5.6) were definitely OOF.

In the end I re-calibrated the AF confimation for use at f/5.6 (where I will use the lens most of the time anyway - I use the lens stopped down and AF confirm at f/5.6 for convenience and speed). The calibrated AF confirmation still seems valid at F/4. At larger apertures (f/2.8 ) I need to fine tune the focus by judging the DOF through my EF-S focus screen. 

At smaller apertures (f/8), the shift effect is masked and no need to manual adjust (which wouldn't work anyway because at those apertures there's no way to judge the DOF with a 14 mm lens).

So for the 50 mm I would suggest AFMA for the aperture you use when taking 'snapshots' where there's no time to manually adjust the focus. And use manual focus for the applications where you have more time and DOF is thin.

[nightbreath]

So for the 50 mm I would suggest AFMA for the aperture you use when taking 'snapshots' where there's no time to manually adjust the focus...

And don't forget to use the focus point you AFMAed your focus for, as 50L has curved focal plane and focus confirmation differs (in ~14 AFMA steps range) throughout focus points.

[Standard]

Is this a reason to avoid this lens? If so..why hasn't Canon fixed this?

Neuro explained it rather well. And I understand wholehearted the concern anyone would have about this lens. It seems there are always chatter about focus shift issues with this specific Canon lens. That said, I just want to say that I have no problem whatsoever with this lens. I use it with my Canon 5D Mark II and focus has never been an issue. Never. One can argued that I am either naive, don't know any better, or too dumb to know what focus shift is. Or one can simply say that I am one of the lucky few that some how got a hold of a perfect specimen. Whatever the reasons are, I can say that I am one happy 50L user...and you will find many of them around.

If you're truly interested in the 50L, my best suggestion for you is to simply purchase it from B&H as they have a great return policy. If you find problems, then simply return it. Spending any more time researching isn't gonna make it easier on your decision. If you truly want to find fault with a lens, you will.

[EOBeav]

Almost everything that has been said about focus shift on the 50L could also apply to the 50mm f/1.4.  It's amazingly sharp with some great bokeh (although not as creamy-smooth as the 50L), but it does have some quirks you have to work through to get the most out of it. Part of the problem I think is that when you're dealing with apertures like f/1.2 and f/1.4, the DOF is so razor thin that it would  be difficult for any AF mechanism to get just right 100% of the time. I tend to have more throw-aways with mine as a result, so I take more snaps of the same comp each time just to make sure. I also make use of the Live View whenever possible. Just my 2/5 of a nickel.

[Juliuslepetit]

Aslo take a look at this post from CR

http://www.canonrumors.com/tech-articles/this-lens-is-soft-and-other-myths/

[cayenne]

If anyone has real world reviews based on their ownership and use of the 50L, please, keep adding them onto this thread...very interesting reading, especially any methods or means you use to work around the focusing issues....

C

Not much too add, but the 50L is a joy to mount and use.  I don't know what body you have, but it seems to be the perfect mate to the 5D3.  It's the right size and weight.  I never stop the lens down, so I right any focus errors to the thin DOF and user error.  I don't know why, but with all my lenses, the 50L is the only one in which never use the hood.

Thanks for all the replies.

I have the 5D3.

I was thinking this 50mm L would also make for an excellent video lens......?


C

[Quasimodo]

Aslo take a look at this post from CR

http://www.canonrumors.com/tech-articles/this-lens-is-soft-and-other-myths/

thanks for a good tip on an interesting article

[Trisal]

I had Mark ii and 50mm 1.2 L lens which was otherwise excellent but very bad back focusing. I was ready to give it up. But then I bought a week ago Mark III and now everything has changed. Usually I get absolutely accurate images with this lens. I bought this new body after I read Karel Donk's blog which you should read.
Read first this:
http://blog.kareldonk.com/canon-ef-50mm-f12-l-defective-by-design/
and after that this:
http://blog.kareldonk.com/canon-eos-5d-mark-iii-review/
especially read what he says about 50 mm lens in the end part of his blog.

[Pi]

The focus shift can only be a problem if you focus too close. I have used two copies of he 50L, and I have never noticed any focus shift problems.

[neuroanatomist]

The focus shift can only be a problem if you focus too close. I have used two copies of he 50L, and I have never noticed any focus shift problems.

Yes, the problem is more evident at or close to the MFD.  But just because that's "too close" for you, doesn't mean that's true for everyone who uses the lens.   One could also say, it's only a problem if you shoot too stopped down - Someone who always shoots wide open would also "never notice a problem."