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Archive 2017 · Sigma 85 Art focusing issue!

  
 
DavidM5
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p.1 #1 · p.1 #1 · Sigma 85 Art focusing issue!


I recently bought a new Sigma 85 Art with my Sigma 35 Art being my most favourite lens on my D5 and D750.

I did find an issue with the outermost focusing points not being able too focus well at all!

The centre one is fine but once I move the focus points to the outer ones, the lens front focuses badly!
I do own the Sigma dock but the individual focusing points are not adjustable.

The lens has now been back to Sigma twice and I still have the same issue!
I have tested my Nikkor 85 F1.4G and it's fine so it's not the camera body.
The Sigma 35 Art is also focusing fine.

Can I trouble fellow owners/ users of the Sigma 85 Art to try this test and post their experiences?

Here is a screen shot of my test.

The left image is the top focus point followed by the middle with the centre ands the right image is the bottom focusing point when shot in portrait mode.






Focusing test.







Focusing test.




Apr 06, 2017 at 12:20 PM
CanadaMark
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p.1 #2 · p.1 #2 · Sigma 85 Art focusing issue!


This is a somewhat common complaint with really fast primes. There are a few explanations, such as a possible decentered lens element, or it could just be other properties of the lens as it appears the inaccuracy is perfectly symmetrical based on your samples. You also may want to re-run the test several times just to rule out PDAF variability.

Does the lens behave the same way when using live view CDAF? That is the test you will want to do.

Also, does this occur at all subject distances? I would test a few different ones.



Apr 06, 2017 at 12:44 PM
DavidM5
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p.1 #3 · p.1 #3 · Sigma 85 Art focusing issue!


Just did the liveview AF test and it works better!

It is not practical however for me to shoot a fast paced event this way.







Apr 06, 2017 at 12:56 PM
CanadaMark
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p.1 #4 · p.1 #4 · Sigma 85 Art focusing issue!


Do you have issues with the outer AF points on any other lenses? Also do you have access to another copy (or a Nikon 85/1.4 or similarly fast lens) that you can borrow or try? You could always exchange it for a second copy to try as well - that would probably give you a solid answer the quickest.

I'd also try at different distances and angles to see if anything points to a specific scenario.

Other than that I would just guess that some property of the lens, whether it be the curved focal plane, a slightly decentered element, or something similar is fooling the PDAF system. The fact that your problem is perfectly symmetrical on the left/right side supports that conclusion. If you tried to tune the lens to the outer points, you would probably find the center was no longer sharp. You're also dealing with only a few mm's of DOF at 1.4, which is a torture test for any system, and real-world shooting will probably leave you with even more variability that you're seeing here. If you look around you will see this is actually a common complaint with other fast lenses, particularly the Sigma 30/1.4 and 50/1.4 as well. It could even be (Sigma) firmware related to some degree. If I had to guess I'd say the lens is operating normally, even though it isn't exactly ideal, but everything hasn't been ruled out. Try some "real world" shooting too and see if it's consistently front focusing the outer points.



Apr 06, 2017 at 02:50 PM
Elijah
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p.1 #5 · p.1 #5 · Sigma 85 Art focusing issue!


Using outer points on a 1.4 prime is ridiculous, regardless of lens make, Nikon or Sigma.
I NEVER use outer points unless I shoot a moving subject while trying to frame it properly without compromising the megapixels.
For the most part, focus with a center point & recompose.
Even with moving subjects, I tend to slap that center focus point on the face and track the person. Later, I crop out the headroom in post.



Apr 06, 2017 at 03:16 PM
DavidM5
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p.1 #6 · p.1 #6 · Sigma 85 Art focusing issue!


CanadaMark wrote:
Do you have issues with the outer AF points on any other lenses? Also do you have access to another copy (or a Nikon 85/1.4 or similarly fast lens) that you can borrow or try? You could always exchange it for a second copy to try .


My Nikon 85 F1.4G focuses fine even on the outer points.
So does my Sigma 35 Art.

At longer focal lengths (8 to 14 feet) the issue is not so apparent.

It sucks because this is my 4th Art lens in my collection and I've been happy with the others.

I was wondering if I should return this lens and keep using the Nikon 85G for this focal length and put the funds towards the new Sigma 135 Art instead.



Apr 06, 2017 at 07:25 PM
DavidM5
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p.1 #7 · p.1 #7 · Sigma 85 Art focusing issue!


Elijah wrote:
Using outer points on a 1.4 prime is ridiculous, regardless of lens make, Nikon or Sigma.
I NEVER use outer points unless I shoot a moving subject while trying to frame it properly without compromising the megapixels.
For the most part, focus with a center point & recompose.
Even with moving subjects, I tend to slap that center focus point on the face and track the person. Later, I crop out the headroom in post.


It's not so ridiculous for me to use the outer focus points...I have not run into this issue ever and I own 25 lenses.

I do find using the center focus point and then recomposing the framing can cause slight misfocusing due to parallax error especially if the subject is close.

I guess I'll have to keep using my 70-200 for instances where I need to move the focus point upwards to the face in portrait mode.




Apr 06, 2017 at 07:33 PM
ATOR
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p.1 #8 · p.1 #8 · Sigma 85 Art focusing issue!


I've had the same problem. After AF-finetuning using the middle AF point the 85mm Art had front focus with the outer right AF points. The Nikon AF-S 85mm f/1.4 on the other hand nailed focus at every AF point so I thought it had to be a Sigma issue.

To my logic defying surprise it turned out to be a camera issue and it was fixed by Nikon. Now the 85mm Art has perfect focus with every AF-point.

My Sigma 35mm Art showed the same behavior but since I use it more for landscapes it was not an issue for me. After the camera fix it too focuses perfectly.

Why this camera AF problem occurred only with the 85 and 35mm Art and none of my other lenses beats me.



Apr 07, 2017 at 04:23 AM
wallstreetonei
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p.1 #9 · p.1 #9 · Sigma 85 Art focusing issue!


Few things (I'm a Canon 1DXii and 5DSR wedding shooter owner so forgive the Nikon inexperience):

1) Does this happen on both the D5 and the D750 the same?
2) The outer (non center) AF points you are using, are they Cross Type / Double Cross type like the Center point? If not, I would not ever use them for F1.4 shots - ever
3) If the lens works at F1.4, in liveview, it is NOT the lens - it is the camera

Let me also say, that I am not saying it is not the Sigma Lens' fault - it most definitely may be. I have experience with 2 Sigma lenses - the 18-35 F1.8 that I bought for use with my Canon C100 Video camera, but I also tried it with my Canon Crop camera the Canon 7D2 - and it was just way too inconsistent so I ended up never using it on the 7D2 as it drove me crazy and there was no rhyme or reason why it would hit and then miss. In the other extreme is the Sigma 24-105 F4 OS which is basically the only lens that I can find that never, ever, ever misses on the Canon 5DSR - it is F4 so it is not a thin DoF lens, but it never misses and this is incredible because getting any kind of tack sharp image with any Canon Prime near wide open on that Camera is near if not totally impossible so I sold them and bought Tamron 45 & 85 F1.8 VC stabilized Primes to use with the 5DSR.

I also have similar outer AF point experience with the Canon 1Dxii with Canon's best and newest Prime - the Otus like $2000 35mm Lii. In order to fix this issue, I disabled all non Cross Type AF pts and the 'problem' is 95% fixed - by 95% I mean that the 1DXii never, ever, misses using the Center AF pt but if you use the most outer AF pt, even a cross type, it just doesn't have a 100% hit rate like the Center AF pt which is a Double Cross type on the 1DXii.

To address your, I can't shoot that way at a wedding, I agree, except, let me say that with the 1DXii (i.e. your D5), I would challenge you to try and use Liveview if you are doing posed portraits and want that thin DoF with rule of 1/3rd composition as on sensor phase detect focus doesn't miss and the D5, must be like the 1DXii, in terms of being extremely fast refresh rates, that it will do a great job shooting this way - I did incorporate this new style with the 1DXii - something I never did, or could conceive of doing, with a 5D3.




Apr 07, 2017 at 05:25 AM
DavidM5
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p.1 #10 · p.1 #10 · Sigma 85 Art focusing issue!


ATOR wrote:
To my logic defying surprise it turned out to be a camera issue and it was fixed by Nikon. Now the 85mm Art has perfect focus with every AF-point.

My Sigma 35mm Art showed the same behavior but since I use it more for landscapes it was not an issue for me. After the camera fix it too focuses perfectly.


Do you know what fix Nikon did?
My Nikon 85 F1.4G focuses fine so it's going to be hard to bring my D5 in to Nikon and claim a focusing issue....



Apr 07, 2017 at 09:16 AM
CanadaMark
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p.1 #11 · p.1 #11 · Sigma 85 Art focusing issue!


Elijah wrote:
Using outer points on a 1.4 prime is ridiculous, regardless of lens make, Nikon or Sigma.
I NEVER use outer points unless I shoot a moving subject while trying to frame it properly without compromising the megapixels.
For the most part, focus with a center point & recompose.
Even with moving subjects, I tend to slap that center focus point on the face and track the person. Later, I crop out the headroom in post.


I use outer points all the time with fast primes, no problems on my D810, missed shots are usually my fault.

DavidM5 wrote:
My Nikon 85 F1.4G focuses fine even on the outer points.
So does my Sigma 35 Art.

At longer focal lengths (8 to 14 feet) the issue is not so apparent.

It sucks because this is my 4th Art lens in my collection and I've been happy with the others.

I was wondering if I should return this lens and keep using the Nikon 85G for this focal length and put the funds towards the new Sigma 135 Art instead.


Well you've pretty well narrowed it down to the lens I would say, especially if your other 85/1.4 does not exhibit the issue. Either it's a property of the sigma lens, or you need to exchange it. The other poster's account of the same problem being fixed by Nikon is curious though - if you don't have problems with any other lenses I would still guess the camera is probably not the problem.






Apr 07, 2017 at 09:59 AM
ATOR
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p.1 #12 · p.1 #12 · Sigma 85 Art focusing issue!


DavidM5 wrote:
Do you know what fix Nikon did?
My Nikon 85 F1.4G focuses fine so it's going to be hard to bring my D5 in to Nikon and claim a focusing issue....


I was in the same position and you're right, it doesn't make sense. If it weren't for the guy in my camera store I would not have sent my camera in for repair and would have returned the 85mm Art.

The Nikon Service Point (in the Netherlands) repair receipt only said AF adjustment and miscellaneous. I heard from someone who was at their repair shop that they use very thin washers to align AF units.



Apr 07, 2017 at 10:33 AM
DavidM5
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p.1 #13 · p.1 #13 · Sigma 85 Art focusing issue!


wallstreetonei wrote:
1) Does this happen on both the D5 and the D750 the same?
2) The outer (non center) AF points you are using, are they Cross Type / Double Cross type like the Center point? If not, I would not ever use them for F1.4 shots - ever
3) If the lens works at F1.4, in liveview, it is NOT the lens - it is the camera


The lens actually works fine in liveview both on the D5 and the D750!

The issue is also much less pronounced at further distances 10+'.

Coincidentally we also have a C100 mk2 and the Sigma 18-35 art lens.
My shooters did not mention any issues with that combo though plus I do not have a Canon DSLR anymore so cannot test that combo.

I think I am going to live with this issue knowing the closeup limitations of the outer focus points since it is fine at further distances but it sucks nevertheless.






Apr 07, 2017 at 10:44 AM
DavidM5
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p.1 #14 · p.1 #14 · Sigma 85 Art focusing issue!


ATOR wrote:
The Nikon Service Point (in the Netherlands) repair receipt only said AF adjustment and miscellaneous. I heard from someone who was at their repair shop that they use very thin washers to align AF units.


Did you send in your Nikon with the Sigma lens?

I doubt Nikon up here would service that combo for me....since the NIkon 85 1.4G works fine..




Apr 07, 2017 at 10:47 AM
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p.1 #15 · p.1 #15 · Sigma 85 Art focusing issue!


DavidM5 wroteDid you send in your Nikon with the Sigma lens?
Just the camera. On my D800E a Nikon AF-S 85mm f/1.4 worked fine too.




Apr 07, 2017 at 03:07 PM
CanadaMark
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p.1 #16 · p.1 #16 · Sigma 85 Art focusing issue!


Because all your other combos work fine, I would be VERY hesitant to send in your camera and introduce the possibility of :

A) Existing lenses not working as well after
B) Shipping damage, or certain tolerances getting out of whack with rough handling it will go through

Try a new Sigma before you do that, IMHO. Or stick with your Nikon 85/1.4 which is still an awesome lens and get the 105/1.4



Apr 07, 2017 at 03:21 PM
wallstreetonei
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p.1 #17 · p.1 #17 · Sigma 85 Art focusing issue!


DavidM5 wrote:
The lens actually works fine in liveview both on the D5 and the D750!

The issue is also much less pronounced at further distances 10+'.

Coincidentally we also have a C100 mk2 and the Sigma 18-35 art lens.
My shooters did not mention any issues with that combo though plus I do not have a Canon DSLR anymore so cannot test that combo.

I think I am going to live with this issue knowing the closeup limitations of the outer focus points since it is fine at further distances but it sucks nevertheless.




Just wanted to follow up and say that the Sigma 18-35 works fine on the c100 - it was only inconsistent on my 7D2 for pictures - not the C100 for video which it is excellent on.

My question is not Liveview on the D5 and D750 but non-liveview - i.e. using the mirror - Liveview by definition is going to work flawlessly. My guess is that the outer AF pts, especially non cross type, on both the D5 and D750, will be equally inconsistent. This issue came up on a Canon forum wrt the 1DXii, and given I am a 1DXii owner, it somewhat surprised me - but since I always immediately turn off all non Cross Type AF pts, I hadn't experienced what this other Canon shooter was experiencing. When I did turn back on these non Cross Type AF pts, and then tested the Canon 35Lii on these outer AF non Cross Type pts, that is when I saw that it became inconsistent.

In the mirror world, not all AF pts are created equally - the center point is usually by far the best, other center region Double Cross Type points are basically as good, Single Cross Type points aren't bullet proof but are usually 90%+ hit rate, and then there are non cross type AF pts, which in my mind, are not AF pts at all - they are marketing AF points that are not ever to be used during profession jobs.

good luck



Apr 07, 2017 at 04:44 PM
souelle74
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p.1 #18 · p.1 #18 · Sigma 85 Art focusing issue!


I have 2 x D810 and the 85mm f1.4 ART

I have same issue, tack sharp in middle, but outer focus point are out of focus , strangely the bottom corners seem to be more off then the top corner. And by out of focus, I mean quite a lot. If I take portrait, with the middle focus point the eye is tack sharp, but if I use far bottom corner the eyes are completely out of focus, not just a bit, I mean in a wait that sharpness cannot be recovered by software)

My test have been done with the camera on a tripod, using a remote and refocusing on each shot, and each point focus point have been tested 4 times.

In live view mode, there is no issue at all. I also tried both a 85mm f1.4G and 85mm f1.4D with no issue at all.



http://i.imgur.com/5Kmmf80.jpg



Jun 01, 2017 at 04:38 PM
Mark_L
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p.1 #19 · p.1 #19 · Sigma 85 Art focusing issue!


Is this on the D5? It has been found that the D500 and D5 do some correction for field curvature.


Jun 01, 2017 at 05:05 PM
charles.K
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p.1 #20 · p.1 #20 · Sigma 85 Art focusing issue!


I have had this issue with Sigma Art lenses to the point I have tested up to five copies of the lens in store. I have spoken with Sigma Australia and I still got the standard white wash replies. Please send in your body with the Art lens and we will see if there is a problem. Even with Nikon since I have had both my D750 and D810 calibrations checked there is no need to send the body in. If you have a Nikon service center nearby it only takes an hour for the techs to check the calibration and readjust if necessary. The Art lens calibrations should fall within specs and with the USB hub is excellent for fine tuning.

I would be 95% certain you have an issue with your 85 Art lens, and I would be adamant with Sigma to replace the lens. To be sure I would go in store and check some other copies of 85 Art lenses. I have a number of suppliers who do appreciate the issues with some Sigma lenses and they allow me the test and if necessary exchange the lenses.

Don't get me wrong I love the Art lenses, as I have the 20, 24, 35 and 50 Art lenses all are superb. I did have to go through a number of copies to be sure the AF worked 95% of the time. Basically the optics of Art lenses are superb, but AF consistency can be an issue.



Jun 01, 2017 at 05:22 PM
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