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Author Topic: Canon 50mm f/1.4 USM focus problem...  (Read 10392 times)

nicku

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Canon 50mm f/1.4 USM focus problem...
« on: August 09, 2012, 05:24:25 AM »
Hi,

I just bought a new Canon EF 50mm f/1.4 USM lens. The problem is that i must microadjust at +20 ( using 7D in camera feature) to get sharp images when the subject is over 2 m from the lens. when i focus under that distance say... 1m the lvl must be on 0 to get sharp images.

Is this normal? or i received a copy with focus problems???

br,

Nik

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Canon 50mm f/1.4 USM focus problem...
« on: August 09, 2012, 05:24:25 AM »

PeterJ

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Re: Canon 50mm f/1.4 USM focus problem...
« Reply #1 on: August 09, 2012, 07:39:11 AM »
Can only speak from personal experience but I used the 7D and 50 / f1.4 combo for quite a while without any AFMA and everything was sharp both at close and far field. After buying a LensAlign it only needed a -1 adjustment which didn't make any real-world difference that I could spot. Your situation doesn't seem normal, mine's always been good over all ranges from MFD to say 10 meters which is probably the furthest I've used it on single subjects.

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Re: Canon 50mm f/1.4 USM focus problem...
« Reply #2 on: August 09, 2012, 08:19:34 AM »
At what aperture are you testing?  If wide open, does it have the same issue at f/4?  Does the picture quality significantly differ if you compare it with LiveView?  If so, then it may be a bad lens and I'd try swapping it.

I found the 50 f/1.4 to have inaccurate focusing wide open but did fine at f/2.8 and smaller.  I had also noticed that the one I used also did worse wide open when the subject was near MFD.  It was a friend's lens that was borrowed, but if was mine, I would have had it sent in and checked out.

nicku

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Re: Canon 50mm f/1.4 USM focus problem...
« Reply #3 on: August 09, 2012, 09:56:25 AM »
At what aperture are you testing?  If wide open, does it have the same issue at f/4?  Does the picture quality significantly differ if you compare it with LiveView?  If so, then it may be a bad lens and I'd try swapping it.

I found the 50 f/1.4 to have inaccurate focusing wide open but did fine at f/2.8 and smaller.  I had also noticed that the one I used also did worse wide open when the subject was near MFD.  It was a friend's lens that was borrowed, but if was mine, I would have had it sent in and checked out.

I tested at f/ 2.2 ; 2.5 ; 2.8 Micro adjustment at 0. the pictures were mushy and blurred. increase the micro adjustment at +20 and the results were much much better.

Using Live view and focusing using contrast detection and micro adjustment at 0 -  the pictures were ok.

At f/ 5,6 ( where this lens performs the best )same think MCA at 0 blurry images ( but more clearer than f/ 2.8) adjusting MCA at +20 the images were ok.

I tested the lens on my old trusty Canon 40D. at all apertures 2.2-5.6 mushy images; using live view and manual focus the pictures were ok.

So i believe is a lens problem.

DJL329

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Re: Canon 50mm f/1.4 USM focus problem...
« Reply #4 on: August 09, 2012, 10:42:46 AM »
I'd exchange it, if possible.  If it's been too long (more than 30 days, depending on the retailer), then I'd send it to Canon for service.
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mememe

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Re: Canon 50mm f/1.4 USM focus problem...
« Reply #5 on: August 09, 2012, 10:44:58 AM »
In near conditions the +20 dont make that much difference.

BUT. The 50 has a Focus shift! If you stop down the focus moves away from you. Keep that in mind! Maybe thats the problem?

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Re: Canon 50mm f/1.4 USM focus problem...
« Reply #6 on: August 09, 2012, 10:45:47 AM »
So i believe is a lens problem.

Sounds reasonable.  My lenses on my previous camera required AFMA near zero, but everything on my current camera is centered around -10.  It might be the lens is within manufacturing tolerance (barely), but the tolerance stackup of the lens and body is too much for AFMA to handle.  In any case, it comes down to which is easier:  exchanging the lens or having Canon service it...

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Re: Canon 50mm f/1.4 USM focus problem...
« Reply #6 on: August 09, 2012, 10:45:47 AM »

nicku

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Re: Canon 50mm f/1.4 USM focus problem...
« Reply #7 on: August 09, 2012, 12:36:28 PM »
I receive the lens today...first i want to try another 50mm to see the difference. IFf the other lens is OK than i will send the lens back to be replaced.

The most odd think is... using live view and contrast based focus system (not camera 19 points AF) the images are very sharp, even at f/1.8 on a crop sensor.
« Last Edit: August 09, 2012, 12:39:33 PM by nicku »

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Re: Canon 50mm f/1.4 USM focus problem...
« Reply #8 on: August 09, 2012, 12:45:57 PM »
I receive the lens today...first i want to try another 50mm to see the difference. IFf the other lens is OK than i will send the lens back to be replaced.

The most odd think is... using live view and contrast based focus system (not camera 19 points AF) the images are very sharp, even at f/1.8 on a crop sensor.

LiveView bypasses the traditional autofocus system, so AFMA does not affect it at all.  What your experience shows is that the optics are fine, but there might be something wrong with the motor/drive system.

nicku

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Re: Canon 50mm f/1.4 USM focus problem...
« Reply #9 on: August 09, 2012, 01:21:41 PM »
I receive the lens today...first i want to try another 50mm to see the difference. IFf the other lens is OK than i will send the lens back to be replaced.

The most odd think is... using live view and contrast based focus system (not camera 19 points AF) the images are very sharp, even at f/1.8 on a crop sensor.

LiveView bypasses the traditional autofocus system, so AFMA does not affect it at all.  What your experience shows is that the optics are fine, but there might be something wrong with the motor/drive system.

More strange ... with AFMA set at +20 the images are as sharp as live view ones that pass traditional AF. In one word i can work with the lens, but in my opinion is not normal to have the AFMA set at maximum +20.

IF i set the AFMA at 0 the images are completely unusable at +20 are sharp. hmmmm

I don't believe is  in the lens tolerance... on a Canon body that not have AFMA is completely unusable (example my 40D).
« Last Edit: August 09, 2012, 01:34:50 PM by nicku »

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Re: Canon 50mm f/1.4 USM focus problem...
« Reply #10 on: August 09, 2012, 01:38:33 PM »
Never had a problem with that combo. Perhaps have you fully adjusted and tweaked the AF system in the 7D?

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Re: Canon 50mm f/1.4 USM focus problem...
« Reply #11 on: August 31, 2012, 09:55:52 PM »
I just purchased my 5d last month as an upgrade from my 20d and have identical AF issues. I have owned the 50mm for a while with zero issues. When I put the Canon 50mm 1.4 on the 5d body, Auto focus is definitly not working properly, seems to get hung up at near focus almost as if there is a mechanical issue, which I am sure it is not as the 50mm works great on my 20d. The 5d works great with the 23-105 F4,  AF is fast with crisp images. I have tried switching modes, from full auto to full custom, and AF settings with no change. If the lens works on the 20d it should work on 5d right? Is this possibly a software issue? I don't know if it's the lens or the body?  Any suggestions would be appreciated.

CharlieB

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Re: Canon 50mm f/1.4 USM focus problem...
« Reply #12 on: August 31, 2012, 10:45:08 PM »
The 50 has a Focus shift!

I've noticed that, but its minimal.   In fact, in inconsistency of focus is much greater than the focus shift.

I've played with two copies of the 50/1.4, and I'm happy with the lens I've got.  Both were the same.  Mild focus shift, not too bad, always away as you stop down.  I've been told.. not sure though, that this is due to the placement of the aperture blades in the optical path, not being exactly - EXACTLY - where they should be.  Supposed to be a not uncommon "fault" with fast lenses using (more or less) Gauss designs.  I know the Leica 50 Noctilux suffers from focus shift, and the rangefinders must be re-adjusted if you plan on shooting mainly wide open.  You match a body to a lens, and to aperture wider than f/2.0 with Leica M's.  Focus shift is not uncommon.

The main problem I've seen, is focus inconstancy with the EF 50/1.4USM.  Mount the lens on a camera, camera on tripod.  Shoot at a newpaper at more or less 2 meters.  Shift the lens to infinity before focusing.  Shift the lens to closest focus before focusing.  Do that about three sets of images.  Shoot at f/2.0 and you'll see what I mean.  The lens, the mechanism is just... inconsistent.   

I like the lens.  I just know that close distance at very wide... say wider than 2.8 is gonna be an issue.  At farther distance, say, stage distances - when shooting a band - its fine at f/2.0 for sharp images in the center.  Shoot it at f/1.4 and the whole affair gets a little low contrast.  All 50/1.4 lenses do that... the Canon is no exception, nor is it the oddball.   If you want a sharp lens wide open at f/1.4 shoot a 50 Summilux 1.4 from Leica.  Those do amazingly well.

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Re: Canon 50mm f/1.4 USM focus problem...
« Reply #12 on: August 31, 2012, 10:45:08 PM »

bdunbar79

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Re: Canon 50mm f/1.4 USM focus problem...
« Reply #13 on: August 31, 2012, 11:09:03 PM »
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CharlieB

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Re: Canon 50mm f/1.4 USM focus problem...
« Reply #14 on: August 31, 2012, 11:25:50 PM »
That link shows a ton of socce photographs.  All shot with the 50/1.4?

At those distances, the 50's focus inconsistency is minimal.

When you get intimate with things... seated portraits for instance, the inconsistency and dof work against each other.

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Re: Canon 50mm f/1.4 USM focus problem...
« Reply #14 on: August 31, 2012, 11:25:50 PM »