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Archive 2013 · AF problems - Sigma 35mm/1.4 on D800
  
 
Steve Park
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p.1 #1 · p.1 #1 · AF problems - Sigma 35mm/1.4 on D800


Received my Sigma 35mm/1.4 about two weeks ago. Spent past ten days or so trying to figure out what's wrong with the lens.

Once I get the focus right, it is crazy sharp @1.4. But using many of the different AF points on D800, the lens just failed lock on focus at least 10 sensors, including 6 cross type sensors in center/lower center. With smaller aperture(2.8 & 4.0) it gets a little better, but many AF sensors, problem still remains. I've taken about 1000 frames using all 51 sensors. Yes, I mounted on a tripod, used remote release.
I'm buying this fast lens to be able to use wide open in low light, but if I can't get it to nail sharp focus, no reason to keep.

Did anyone else experienced the same? Can someone point what the problem might be, could this be user error? FYI, I sent my D800 to Nikon LA, repaired the LEFT AF problem.
I've also tried with my other Nikon G lenses(2.8 & 4.0), they work just fine.

Thanks for your help.



Mar 21, 2013 at 01:50 PM
hjanssen
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p.1 #2 · p.1 #2 · AF problems - Sigma 35mm/1.4 on D800


Steve Park wrote:
With smaller aperture(2.8 & 4.0) it gets a little better, but many AF sensors, problem still remains.

Seems strange to me that the aperture has anything to do with the AF, because that is always done fully open, probably you don't notice a little off focus because of the increased DoF,



Mar 21, 2013 at 02:00 PM
Red G8R
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p.1 #3 · p.1 #3 · AF problems - Sigma 35mm/1.4 on D800


I don't have the D800 but I've not had any focus problems on the D4 or D600 with this lens. It would be nice if you could try another sample at a local store and see. You seem to have covered all bases in terms of accuracy so it might be the lens.


Mar 21, 2013 at 02:02 PM
Steve Park
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p.1 #4 · p.1 #4 · AF problems - Sigma 35mm/1.4 on D800


hjanssen wrote:
Seems strange to me that the aperture has anything to do with the AF, because that is always done fully open, probably you don't notice a little off focus because of the increased DoF,


I did try with different apertures to compare with my other Nikon lenses(70-200mm/2.8 VRII @70mm and 200mm & 16-35mm/4.0 @35mm , I don't have any other fast lens), it seemed to get better, but not much better. Probably you're right, increased DoF.



Mar 21, 2013 at 02:21 PM
snapsy
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p.1 #5 · p.1 #5 · AF problems - Sigma 35mm/1.4 on D800


Is it failing to lock or locking but with inaccurate focus? There's a thread for the latter here.


Mar 21, 2013 at 02:57 PM
Steve Park
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p.1 #6 · p.1 #6 · AF problems - Sigma 35mm/1.4 on D800


snapsy wrote:
Is it failing to lock or locking but with inaccurate focus? There's a thread for the latter here.



It locks but inaccurate focus. Some are barely acceptable, yet some are clearly unacceptable even viewing at very small size less than 25%. The thread you referred is somewhat different AF problem than what I have. On my lens, weak focus points are spread out, not just ouside or inside, makes it more difficult to understand.

I tested from 5-6' away, 50 times the focal length. And some other distance.



Mar 22, 2013 at 12:21 AM
geniousc
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p.1 #7 · p.1 #7 · AF problems - Sigma 35mm/1.4 on D800


I think there are two versions of this lens for Nikon, the early ones and recent ones. Some of the early ones had some sort of firmware problem pertaining only to the D800. I had an early one that I had to return too, the second one is spot on everywhere between MFD and infinity. Either return it or send it to Sigma.

gene



Mar 22, 2013 at 12:43 AM
Steve Park
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p.1 #8 · p.1 #8 · AF problems - Sigma 35mm/1.4 on D800


I received my lens on Mar 12, makes it one of the latest batch, serial 50022xxx. I already got the RMA from BH, but hate to return and wait for a replacement in a month or so!
But I have to do what I have to do unless there is a fix for this problem.

Steve



Mar 22, 2013 at 12:48 AM
splathrop
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p.1 #9 · p.1 #9 · AF problems - Sigma 35mm/1.4 on D800


Using outer auto-focus points on an f/1.4 lens, and then shooting wide open, is a stern test. Problem is that the outer part of the frame is never as sharp as the center, and the focusing is done using that less-sharply-rendered part of the image, which probably makes your auto-focus system guess a bit. Then you shoot wide open, assuring the least possible depth of field, so no chance of correcting any focusing errors by recording added depth of field in the image you make.

When people tell me they get reliably perfect results doing it that way, I'm inwardly skeptical, but don't discount what they say to zero, because, hey, they know what they see and I don't. But it's a stern test. My 5d III does what I consider to be a superb job with the 35L wide open, including on the outer points. I use them without hesitation. But they will occasionally be a bit off, and the center points are a bit more reliable.

You say the weak points are spread out. Have you tested systematically enough to prove that some points are always bad, and others always good? That would be useful information.



Mar 22, 2013 at 01:07 AM
Steve Park
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p.1 #10 · p.1 #10 · AF problems - Sigma 35mm/1.4 on D800


splathrop wrote:
You say the weak points are spread out. Have you tested systematically enough to prove that some points are always bad, and others always good? That would be useful information.


I did test shots at different aperture as well(my first post above). At 2.8 and 4.0, to campare with other Nikon AF lenses I have. Some improvements(due to DoF, I assume), but compared to shots taken with other Nikorr lenses at same aperture setting, the difference is easy to tell. But I can't say all weak points were 100% weak, but mostly.



Mar 22, 2013 at 01:17 AM
 

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geniousc
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p.1 #11 · p.1 #11 · AF problems - Sigma 35mm/1.4 on D800


Steve Park wrote:
I received my lens on Mar 12, makes it one of the latest batch, serial 50022xxx. I already got the RMA from BH, but hate to return and wait for a replacement in a month or so!
But I have to do what I have to do unless there is a fix for this problem.

Steve


I was confronted with the same situation. I returned mine and looked elsewhere for one in stock. Finally I was notified that B&H had stock, I jumped on it. I don't think you will have to wait as long as I did, the pipeline has to be getting full. Good luck. You can always return it to Sigma for repair, it may be faster than getting it replaced.

gene



Mar 22, 2013 at 03:28 PM
ash4390
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p.1 #12 · p.1 #12 · AF problems - Sigma 35mm/1.4 on D800


Bumping this thread..

Is anybody having any experience with this lens being soft at f/1.4 when focused at infinity?

Mine was pretty good, but recently (after the D800 firmware update) been not so good at distances. Will post a sample picture after work today.



Apr 12, 2013 at 04:55 PM
mdemirha
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p.1 #13 · p.1 #13 · AF problems - Sigma 35mm/1.4 on D800


I just returned a copy that had AF issues on my D800. My D800 is serviced by Nikon for left AF issue, and it works quite well now (not perfect, but acceptable).

My copy of 35 mm was very sharp at the center, but it back-focused very significantly using the outer points. All outer points had issues, but leftmost and rightmost were the worst (progressively gets worse as you go to leftmost or rightmost). I have a 28mm, and it doesn't have this issue.

Another copy is on its way. I will update the thread once I receive that copy.



Apr 13, 2013 at 04:24 AM
Nikon_14
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p.1 #14 · p.1 #14 · AF problems - Sigma 35mm/1.4 on D800


Steve Park wrote:
I already got the RMA from BH, but hate to return and wait for a replacement in a month or so!



My Sigma 85mm f/1.4 only took a week to get back. Remember, you're not sending this back to Melville or El Segundo; Sigma seems to "get it" that honoring warranties = profit in the form of future sales.



Apr 13, 2013 at 05:03 PM
ash4390
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p.1 #15 · p.1 #15 · AF problems - Sigma 35mm/1.4 on D800


Well, here is my update. Something seems to be severely wrong with my Sigma lens.

The lens cannot focus properly at distances > 6' feet or so, I'm not sure what is going on with it. Here are some examples, thoughts?

edit: I should clarify, these are 100% crops, SOOC.





-20 AF Fine tune

  NIKON D800    35.0 mm f/1.4 lens    35mm    f/1.4    1/8000s    100 ISO    0.0 EV  






0 AF fine tune

  NIKON D800    35.0 mm f/1.4 lens    35mm    f/1.4    1/8000s    100 ISO    0.0 EV  






f/2.8 - 0 fine tune

  NIKON D800    35.0 mm f/1.4 lens    35mm    f/2.8    1/4000s    100 ISO    0.0 EV  






f/1.4 - 0 fine tune

  NIKON D800    35.0 mm f/1.4 lens    35mm    f/1.4    1/8000s    100 ISO    0.0 EV  




Apr 14, 2013 at 11:41 PM
Steve Park
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p.1 #16 · p.1 #16 · AF problems - Sigma 35mm/1.4 on D800


Nikon_14 wrote:
My Sigma 85mm f/1.4 only took a week to get back. Remember, you're not sending this back to Melville or El Segundo; Sigma seems to "get it" that honoring warranties = profit in the form of future sales.



So, your Sigma 35mm/1.4 is working perfectly as it should? I could have sent to Sigma for adjust, but if the adjustment doesn't fix all the problem, I'll miss the return window and stuck with it. The AF problem I had is so random, I honestly didn't think it could be fixed.



Apr 17, 2013 at 04:21 PM
Nikon_14
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p.1 #17 · p.1 #17 · AF problems - Sigma 35mm/1.4 on D800


Steve Park wrote:
So, your Sigma 35mm/1.4 is working perfectly as it should? I could have sent to Sigma for adjust, but if the adjustment doesn't fix all the problem, I'll miss the return window and stuck with it. The AF problem I had is so random, I honestly didn't think it could be fixed.



I have an 85mm Sigma f/1.4. After having an R-something motor replaced, it works perfectly fine. After the 35mm f/1.4 has been out for a little more, I'll likely buy it, based on my experience with the 85mm.



Apr 17, 2013 at 04:41 PM
Steve Park
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p.1 #18 · p.1 #18 · AF problems - Sigma 35mm/1.4 on D800


My 3rd Sigma 35mm/1.4 should be here tomorrow. If this doesn't work, there won't be another try. I really hope this one works as it should.


Apr 17, 2013 at 04:50 PM
m_appeal
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p.1 #19 · p.1 #19 · AF problems - Sigma 35mm/1.4 on D800


Odd. My first one works out of the box perfectly


Apr 17, 2013 at 10:10 PM
Steve Park
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p.1 #20 · p.1 #20 · AF problems - Sigma 35mm/1.4 on D800


m_appeal wrote:
Odd. My first one works out of the box perfectly


I just received a used 24-70/2.8G, it works perfectly on my D800(with -5 AF tuning). But Sigma 35mm/1.4 is a different story. I hope my new one works perfectly like yours. Keeping my fingers crossed.



Apr 17, 2013 at 10:38 PM
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