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Archive 2012 · 50L and outer focus points

Jim Levitt
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p.1 #1 · p.1 #1 · 50L and outer focus points

I recently acquired a 50/1.2L. I knew I'd have to stick to just the center point on the 5D2 with the lens wide open. I expected the 5D3 would allow me to utilize outer focus points, especially the cross-types, and thus avoid focus-recompose or cropping workarounds.

If I use the center point on the 5D3, the 50L focuses accurately at f/1.2. If I shift to an outer focus point (the furthest out cross-type sensors in landscape orientation) and use that to focus on the same target, the result appears to be front focused. I was testing by focusing on the spine of a book in a bookshelf, about 4 feet away, at about 45 degrees. With the centerpoint, focus was accurate and repeatable. Same technique, same target, but using an outer focus point, focus was not accurate.

Even if the lens has some amount of field curvature, should an outer focus point produce a properly focused image, if there's no focus-recompose involved?

Does the 50L always behave like this? If so, how do you use it for a shallow depth of field off-center portrait?

Apr 08, 2012 at 10:45 PM

sirimiri
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p.1 #2 · p.1 #2 · 50L and outer focus points

Is your test subject static? If so, what does an image using the AF system, versus an image using live view yield, in terms of your image quality expectations?

Apr 08, 2012 at 10:50 PM

Gochugogi
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p.1 #3 · p.1 #3 · 50L and outer focus points

I don't have a 5D3, but in decent light (hand holdable) my 5D2/50 1.2L works fine with the outer points. In low light I stick with the center. Oddly my original 2005 5D didn't focus worth a damn with outer points and the 50L in any light. The outer points also work fine on my 7D with the 50L.

Apr 08, 2012 at 11:53 PM

surf monkey
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p.1 #4 · p.1 #4 · 50L and outer focus points

This guy seems to have no problem with the outer focus points and the 50L.
He's a Nikon guy and seems to love the combo.
http://www.ryanbrenizer.com/2012/03/a-nikon-users-review-of-the-canon-5d-mark-iii/

I wonder if there is a compatibility issue between specific bodies and lenses?

Apr 09, 2012 at 12:30 AM

UCSB
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p.1 #5 · p.1 #5 · 50L and outer focus points

I would not test focus by shooting an inclined surface! Try it parallel to a good test target and report back. If it works on a parallel surface, then see if your AF point shown might be just a little off of the actual AF point thru the VF. F 1.2 handheld at 4.5 feet will only give you narrow DOF, seems like a pretty bad test.

Edited on Apr 09, 2012 at 12:41 AM · View previous versions

Apr 09, 2012 at 12:38 AM

mttran
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p.1 #6 · p.1 #6 · 50L and outer focus points

Jim, i have never failed an AF on 1ds2 & 50L regardless what sensor point. My 5d2 behaves just like yours. So, it's not 50L. Look like 5d3 has been fixed this AF problem arcording to many has reported.

Apr 09, 2012 at 12:41 AM

UCSB
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p.1 #7 · p.1 #7 · 50L and outer focus points

One other thing to keep in mind ... THE AF POINT YOU ARE USING IS NOT SUPPORTED ON THE 50 1.2 ON THE 5D3. The 50L is supported in max accuracy by the 5 center points. It is supported for cross point accuracy on the 41 points. So retest by moving over one column of points. There is a CF you can set to only show the 41 cross AF points that is the best approach with these types of lenses.

Apr 09, 2012 at 12:44 AM

UCSB
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p.1 #8 · p.1 #8 · 50L and outer focus points

You can check your manual for supported AF points or on page 37 of this write-up.

http://downloads.canon.com/CDLC/EOS_1DX_AF_Guide_CDLC.pdf

Please post your retest results. This may affect some of my lenses.

Apr 09, 2012 at 12:46 AM

Jim Levitt
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p.1 #9 · p.1 #9 · 50L and outer focus points

UCSB wrote:
I would not test focus by shooting an inclined surface! Try it parallel to a good test target and report back. If it works on a parallel surface, then see if your AF point shown might be just a little off of the actual AF point thru the VF. F 1.2 handheld at 4.5 feet will only give you narrow DOF, seems like a pretty bad test.

This was a "quick and dirty" test, as I was getting ready to take the 5D3 out for the very first time. I figured this was the closest I could replicate photographing someone in an off-center manner. Using an outer point on the eye of a person positioned on the side of the frame, but not at a 90 degree angle to me, would be a typical composition for me. If the camera/lens combo won't focus on a static subject with good contrast, how can I expect it to do so on someone's face? It doesn't appear to be a microadjust issue. The center point yields accurate focus.

I'll do some more testing later this week when I have more time. I'm glad to read the reports from others here that the lens normally does focus properly off center.

Edited on Apr 09, 2012 at 01:18 AM · View previous versions

Apr 09, 2012 at 12:50 AM

Jim Levitt
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p.1 #10 · p.1 #10 · 50L and outer focus points

UCSB wrote:
One other thing to keep in mind ... THE AF POINT YOU ARE USING IS NOT SUPPORTED ON THE 50 1.2 ON THE 5D3. The 50L is supported in max accuracy by the 5 center points. It is supported for cross point accuracy on the 41 points. So retest by moving over one column of points. There is a CF you can set to only show the 41 cross AF points that is the best approach with these types of lenses.

I was using the cross type points, in the second row. I have the camera set to show all the points, but the non-cross AF points blink.

Apr 09, 2012 at 12:51 AM

UCSB
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p.1 #11 · p.1 #11 · 50L and outer focus points

OK .. well maybe more testing will shed some light on the situation. Given the target, you might want to consider using the smaller point based AF option to narrow your focus point down.

Apr 09, 2012 at 12:54 AM

yurch
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p.1 #12 · p.1 #12 · 50L and outer focus points

Jim Levitt wrote:
This was a "quick and dirty" test, as I was getting ready to take the 5D3 out for the very first time. I figured this was the closest I could replicate photographing someone in an off-center manner. Using an outer point on the eye of a person positioned on the side of the frame, but not at a 90 degree angle to me, would be a typical composition for me. If the camera/lens combo won't focus on a static subject with good contrast, how can I expect it to do so on someone's face? It doesn't appear to be...Show more →

I have the same issue as you but with Sigma 50 1.4

It also frontfocuses on outer focus points.

Apr 09, 2012 at 02:11 AM

Sven Jeppesen
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p.1 #13 · p.1 #13 · 50L and outer focus points

It works good with the outer focus points on the older 1 series bodies. And I don't think the 5D3 is less good

Apr 09, 2012 at 03:33 AM

deepbluejh
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p.1 #14 · p.1 #14 · 50L and outer focus points

On the 5DIII, my 50L is perfect using the center and outer AF points. In fact, it's staggeringly sharp on the 5DIII, which makes me think AF was less than perfect with it on my 5DII.

Corrected!

Edited on Apr 09, 2012 at 01:43 PM · View previous versions

Apr 09, 2012 at 07:30 AM

Peter Gregg
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p.1 #15 · p.1 #15 · 50L and outer focus points

deepbluejh wrote:
On the 5DIII, my 50L is perfect using the center and outer AF points. In fact, it's staggeringly sharp on the 5DII, which makes me think AF was less than perfect with it on my 5DII.

Who's on first??

Peter

Thanks for the correction

Now I understand what you are saying. And it is quite important too!

Edited on Apr 10, 2012 at 09:37 PM · View previous versions

Apr 09, 2012 at 01:40 PM

emiller90
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p.1 #16 · p.1 #16 · 50L and outer focus points

I don't have the 50L, but find the 35L is inconsistent on the mark III outer cross type points.

Apr 09, 2012 at 02:11 PM

paregorike
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p.1 #17 · p.1 #17 · 50L and outer focus points

emiller90 wrote:
I don't have the 50L, but find the 35L is inconsistent on the mark III outer cross type points.

ALL of my Canon lenses are pretty accurate on the 5D III with proper technique.

Ron

Apr 09, 2012 at 04:50 PM

Peter Gregg
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p.1 #18 · p.1 #18 · 50L and outer focus points

emiller90 wrote:
I don't have the 50L, but find the 35L is inconsistent on the mark III outer cross type points.

Is this using the 41 point higher precision focus points only layout or all point layout?

Peter

Apr 10, 2012 at 10:07 PM

rscheffler
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p.1 #19 · p.1 #19 · 50L and outer focus points

Just to understand better, did you try more than one of the peripheral points? Might be worth testing all of the cross points to see what kind of consistency you get. My impression, from my 1D bodies, is that some of the points don't like some of my lenses, but a neighboring point for a given lens might work better. This could just be something I think I'm seeing... or maybe not. From my understanding, it's possible for Canon to calibrate the points separately. If you're finding that there is a consistent error with the peripheral points, then a trip to Canon might be in order (might be worth calling them to get their opinion). Especially since others here are saying they're getting great results with that combo and peripheral points.

Something else to keep in mind: the closer the subject with the 50L, the stronger the uncorrected spherical aberration produced by the lens will be. Since AF is performed wide open, the AF sensor sees an image that is degraded (lower contrast) due to the SA, and this might be more of an issue for the peripheral points to manage. Farther subject distances result in less SA with this lens, so for those who have been getting great AF results, were you focusing on equally close subject matter?

Apr 10, 2012 at 10:37 PM

emiller90
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p.1 #20 · p.1 #20 · 50L and outer focus points

Peter Gregg wrote:
Is this using the 41 point higher precision focus points only layout or all point layout?

Peter

Don't get me wrong. I'm impressed with the new autofocus capabilities of the 5d Mark III. I am only using the 41 cross point sensors, and am able to obtain acceptable focus nearly all the time. However, they are occasionally soft. On whole, I am getting better results than I remember with the 1Ds Mark III. That is rather impressive, considering that the outer points are located more peripherally than the 1D. Part of the problem is that the 35L is a little soft as you move from the center, but on occasion I am able to get very sharp captures off center. But even when stopped down a bit, there are occasionally soft. I don't doubt that poor technique is playing a role. Nonetheless, it is a little inconsistent for me.

Apr 10, 2012 at 11:11 PM

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