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Sigma 35mm 1.4 / D800 e AF issues

Guy Mancuso

Administrator, Instructor
Well I sold my first Sigma lens and decided to buy it again. The first one just seemed problematic on this body. Now the new one I just bought still has back focusing issues but so does my Nikon 50 1.4 and there both deadly at -20. No room for play but its on the money and BTW the Sigma 35 just smokes the Nikon 50mm 1.4 bt that's not the thrust of this thread though but working with both of them today I noticed something that I think is the issue with the sigma 35mm and why some are having issues. Lets start with the Nikon using the shutter button or the back rear focus button once you hit the focus it stops focusing and there is no hunting . I'm on AF-S single point in the center.

Now I think I found why reverse engineering is problematic . On the Sigma using the same shutter or rear focus button once you hit the focus immediately if you continue to hold before firing it has a tendency to continue to focus and it should not do that but it does and this is where you get inconsistent results maybe 3 out of 7 shots get nailed but the rest are off. Now thinking back the same issue was there on the first Sigma. I'm directly chalking this up to either a firmware issue or this reverse engineering of AF is wrong.

Now I did find a solution and you need to be kind of quick and its a two finger operation. Either the rear focus or shutter button in either case if your initial press than at the same time hit the AE/AF lock button immediately without pause it will hold the focus and it does it almost every time. Now its really hard to hit the rear focus button and the AE/AF lock so you really need to use the shutter and AE/AF lock in tandem. So try this just hold down the Shutter button and get focus on something and keep holding it and you'll notice a very slight shift. Why it does not hold is really the issue its like its still hunting but if you start over throw it out of focus than go back to your test image hit it again than immediately hit the lock you will notice your in focus.

One other trick I found with everything still in AF you want to manual focus hit the AE/AF lock when your on that way it does not hunt while holding down the shutter release.

Now love to see some others try this and see if it works. This does give me some thoughts as I remember I had some of the same focus errors with my old Sigma 150 2.8 which if I recall had the same issue. This brings up some interesting problems with AF and Sigmas. Am I seeing something that no one else has noticed or is it maybe my body. But this is pretty hidden if your not watching directly for it. Now I don't want to scream foul either but I find this kind of odd. But the Sigma 35mm 1.4 is maybe one of the sharpest lenses I seen wide open. It's certainly no question the best 35mm lens I have had and that's up aganst the Nikon 35 1.4 g and the Zeiss 35mm F2 so it is up against some serious glass .
 

D&A

Well-known member
Guy, for the moment I'll keep this brief (due to enormous amount of work I have to complete) but I'll mention a few quick things. Many Sigma lenses often "micro" hunt with slight chattering being heard as it attempts to settle in on a focus point. After pressing the shutter release button half way down (or the rear focus button)....if you lift your finger up and quickly repeat this process a number of times in succession, you'll often find the focusing distance the lens selects slightly different. With a slower lens or when stopped down the depth of field will usually cover focusing anomalies. With a f1.4 lens, it's quite a different story as you well know. This micro hunting occurs less with a Nikon lens and even most Tamron's so it may have something with reverse engineering the chip as opposed to Tamron which I believe pays royalties.

When I do press the shutter button continuously and repeatedly, I eventually find I can fairly quickly determine the focusing point it generally selects the majority of the time, but of course this is no way to work fast.

The old original Sigma 120-300 f2.8 was notorious for this micro chattering but their 100-300 f4 does exceptionally well. The Sigma 150 f2.8 macro (non OS) also does fairly well, so it appears to be lens dependent and might depend on the spread of the focusing helical/scale.

Dave (D&A)
 

tashley

Subscriber Member
Guy. I just got my fourth copy today and will take a good look at the behaviours you describe but sadly I think this one has to go back, too: yet again it is smeary on one side (this time the left) and isn't acceptable even at distance til f8 and not perfect even then, bummer because the central performance is best at f4. As a look lens I like it but it also has weird mid field issues, probably a field curvature thing. I'd kill for a good copy but....

How is yours at the edges? You had a problem with the first copy I remember...
 

Alon

Not Available
Guy. I just got my fourth copy today and will take a good look at the behaviours you describe but sadly I think this one has to go back, too: yet again it is smeary on one side (this time the left) and isn't acceptable even at distance til f8 and not perfect even then, bummer because the central performance is best at f4. As a look lens I like it but it also has weird mid field issues, probably a field curvature thing. I'd kill for a good copy but....

How is yours at the edges? You had a problem with the first copy I remember...
1- Would you keep the lens if it was not for landscape photography.

2- I just looks that this lens is not for long shots but more medium and close photography.

Do you concur?
 

tashley

Subscriber Member
1- Would you keep the lens if it was not for landscape photography.

2- I just looks that this lens is not for long shots but more medium and close photography.

Do you concur?
honestly, until I get a copy that is not suffering obvious asymmetry, I can't tell what its real curvature is so I can't say what it would be good for. I love the look of the bits of the frame that are sharp and of the bits that are OOF, but they are not always where they should be....
 

Quentin_Bargate

Well-known member
1- Would you keep the lens if it was not for landscape photography.

2- I just looks that this lens is not for long shots but more medium and close photography.

Do you concur?
Well, no, I would not concur at all. My copy is my sharpest lens tripod mounted and used for landscapes. It's far better at the edges than, say, the Nikon 24mm PC tilt shift lens, and as good or better than my very good Zeiss 21mm f2.8 the biggest issue I have is avoiding loss of resolution due to camera shake or vibration but that of course is not the fault of the lens but an issue with the design of the D800E.

Of course I guess it all depends on your own copy of the lens, so your mileage may vary, as they say.

On the other hand, I agree with Guy that this lens does not always hit the right focus spot every time. I sometimes see the same focus anomalies that Guy refers to. That howver does not impact upon landscape work, and only sometimes does it affect other work, but it is less consistent than, say, the Sigma 85mm f1.4
 

tashley

Subscriber Member
Quentin, I was about to post some sample images for you that I took in London yesterday but Doh I have left my memory card in the reader of my computer there and won't be back for a week. So I can describe them: a roof top view with highly detailed subject matter from about forty feet away to several miles, focussed on a spot about a half mile away once, wide open, then shot at all apertures. The centre is gorgeous, the right hand side is quite good even wide open, the left is a mess and doesn't get close to tidy until f5.6 and not even totally convincing at F8 even when viewed at 50% on screen. Some mid-field weaknesses on both sides until F8 too.

Now on the one hand there are respectable Leica lenses that don't tighten to the edges until F8 so one might accept this behaviour. On the other, I hate the look of asymmetrical lenses. Not just when you want the edges sharp, but for the strange variations in OOF areas which I think are subliminally weird.

I shot another two series and one of them was just about OK at F5.6 so it does imply to me that this is about placement of field of focus to some extent: this copy, like the previous three, requires a strong + AFFT of +20.

It sounds as if you have the only copy that isn't thusly afflicted that I have heard of. But it also strikes me that you might not have shot the sort of subject matter on which it shows - so I thought I'd just check with you and ask that question so I can ex-out the hypothesis that there is something truly endemic going on...

Thanks!
Tim
 

Quentin_Bargate

Well-known member
Hi Tim

I admit I am probably not as thorough as you in testing lenses, I tend to just use them and if they work for me, then I'm happy. I think my copy has a very slight right side issue but I'm not sure and I don't see it on landscapes or most other shots. I may check again, but if its there, it is very slight.

I have had some dodgy lenses in my time. The first copy of a Sony Alpha Zeiss 24-70mm has serious asymmetry; I sent it back. The second copy was more or less perfect and I still have it. I have variations is accuracy from my Hasselblad lenses.

Maybe we are reaching the limits of currently achievable precision on very high resolution sensors on the 35mm format using old film-based legacy camera mounts and optical engineering. Sigma claim to test each lens and the "Art" series are intended to be high end performers, which mine appears to be.
 

tashley

Subscriber Member
I hear you Quentin - and I might well just keep the lens because as you say, it won't show in most shots. But I have really noticed in re-testing all my Leica lenses on the new M240 that there are just never any issues with asymmetry. I have become so used to this problem after a year with the D800, where about half the lenses I have purchased have had the problem to some degree!

BTW my definition of it 'mattering' is if it is still clearly visible when downsized to a 25mp resolution: in other words, it would show on a D600 class camera.

So please don't test your lens. You love it and I don't want to come between you!
 

Guy Mancuso

Administrator, Instructor
I just got done testing a bunch of glass will post as I get them done. Sigma included on two tests actually.
 

Guy Mancuso

Administrator, Instructor
Okay I have a good copy. Edges are very good on both sides and F4 is as good as F8. Lots of processing but every prime Zeiss 25 F2, Sigma 35, Nikon 50 1.4 and Nikon 85 1.8 all smoke my 24-70 Nikon. I have a good zoom too.. feeling pretty good about this
 

tashley

Subscriber Member
:D Damn you Mancuso :D

I did speak to Sigma tech today and said, look this is my fourth copy and they've all had a weak edge and needed too much + AFFT and the second one, which I sent to you to get fixed so I knew I had a good one, you just replaced with another not quite right copy so can I please ask you to actually look at this one which I am now going to send you, please? And they said, for sure - and they were really nice about it too.

So I am going to send it in: this lens is one of the very best I have ever used, I think it quite possibly outclasses the Leica 35 Lux, and I am not going to stop til I have a great copy....

Thanks a lot for the info Guy. Much appreciated.
 
Interesting Guy, I just picked my D800e up on friday and should have my Sigma 35mm 1.4 early next week... hoping I get a good copy! I have bought locally though from the guy who is my Hasselblad Dealer and he said if its bad he will swap it till I get a good one.
 

Guy Mancuso

Administrator, Instructor
Yes as you can see get one that you can return. This is my second and feel I got lucky on it. It's maybe my sharpest lens.
 

tbeam

New member
I bought the Sigma 35mm f/1.4 DG lens last week here in the UK and realised straight away that when using the central focus point on my D800 the lens was front focusing badly. Note that the AF on my D800 works flawlessly with all of my Nikon lenses.

I fine-tuned the autofocus by shooting two different types of high-contrast flat targets at various distances (mainly between 40 x focal length and 60 x focal length). The targets were positioned on a well-lit vertical wall and I used a tripod and a remote release shutter.

The outcome was that the fine tune needed to be set to +15 to achieve excellent results for the central focus points. However, with this setting images taken using the side focus points (either left or right) were out of focus. After a few additional tests, I realised that the extreme left and right focus points required no AF fine tune adjustments.

Once I get the focus right, the lens is incredibly sharp, even at f/1.4. But I bought this fast lens to be able to use it wide open in low light, and achieving accurate focus is essential for me. I would not mind correcting the AF with fine tune, but the problem is that I cannot find a “global” correction that would work across the frame. In other words, if I calibrate the central focus points, I get out of focus images when shooting with the far right/left focus points, and vice versa.

Judging from the conversations on a number of forums on the internet, this seems to be a widespread problem with the Sigma 35mm / D800 combination.

I really like this amazing lens and wish I could keep it but I think I will return it to Amazon. Do you think I should try and get it exchanged or should I go for a refund and wait for Sigma to resolve this known issue before purchasing a new copy?
 

Guy Mancuso

Administrator, Instructor
There is a firmware coming to address the side AF points on the D800 series. It's a matter of when Sigma gets it out the door. This came from a Sigma repair shop . Myself I only use the center point and recompose . But that is something I always have done for years is focus recompose so I am used to doing that.
 

tbeam

New member
I just spoke with the technical department of Sigma UK.
Their comments are as follows:

*) They recently received a couple of 35mm f/1.4 lenses to be checked for AF issues.

*) They did not comment on the actual volume of lenses being returned / sent it for calibration

*) They confirmed that this is NOT a firmware issue. The lens needs to be calibrated

*) Customers can send the lens in by itself for calibration, but they recommend to send it together with the camera

*) They are very busy and understaffed. They will keep the lens for 2 to 3 weeks

The fact that they confirmed this is not a firmware issue leads me to think that purchasing their USB dock would not allow customers with AF issues to fix their lenses. These are to be calibrated in a lab.
 

tashley

Subscriber Member
Mine is off with them at the moment to have its asymmetry fixed, but I have not noticed the 'chattering' focus issue, just excessive +compensation needed and a slanted field of focus.

My fourth copy!
 
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