# Sigma 135 f1.8 Art; Inconsistent AF



## Eldar (Apr 22, 2017)

It may be that Sigma is after me and is determined to keep me away from their lenses ...

Even though I made myself a promise, not to get another Sigma lens, I fell for the initial reports from the likes of Dustin Abbott, about AF improvements and I picked up the 135/1.8 yesterday.

I initially tried it around the house, prior to run it through Focal. Some decently in focus, others totally off. I have seen similar from other lenses in the past. When AFMA is off, AF may be inconsistent. So, today, I gave it a run through Focal. And what a depressing experience that was. On all runs the red dots were all over the place. On the 5DIV I got a +12 on run 1, +8 on run 2, -2 on run 3 and unable to determine on run 4. I then switched to the 5DSR and got a +12 on run 1, +2 on run 2 ... and then I gave up.

I then took it on the 5DSR outside, to test some more. I just chose a value of 7 (in between 12 and 2) and used various focusing points. The results, unfortunately, was very inconsistent. I shot the same targets several times, most of them on a tripod, I repeated manually turning the lens out of focus, not by much and always towards minimum focus distance. The result was front focus on one, back focus on the next. I also used the LensAlign setup and got the same result. 

Needless to say, this just confirms my previous experiences with the 35/1.4 and 50/1.4 Art lenses, of which I went through several copies of each. I´ll take it back to the shop next week and I´ll ask them to do the AFMA for me. Fingers crossed, they can prove that I have done something wrong. I have my doubts though, considering all the AFMA runs I have been through over the years, with a significant number of cameras and Canon lenses.

So to those of you who bought this lens. Have you run it through FoCal? Have you tested for focus consistency? If you have a magic trick, please tell me.


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## GMCPhotographics (Apr 22, 2017)

Sorry to hear that Eldar, but I'm not surprised. I rather vocally gave up on Sigma a few years back and nothing I've read so far has even vaguely tempted me back to that particular lens brand. Canon charges a high price for their L lenses for good reason...they are properly invested in terms of R&D and manufacturing. If I add resale value into the mix...Sigma (in my experience) are a waste of time and money. Where as Canon...I've not had a dud and I've bought and sold a lot of them them.


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## Eldar (Apr 23, 2017)

Yes GMC, I believe you are right. I just thought all the praise and all the positive posts by happy customers meant something. Unless a miracle happens (which translates to stable and consistent AF), I´ll get rid of this one and just wait for the L-lens upgrades to the 85 and 135.


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## Aichbus (Apr 23, 2017)

I own the 24 Art and the 50 Art. I previously had used them on a 6 D and found the focus consistency good enough. Recently I purchased a 5DsR and now, the inconsistency is barely tolerable. I nevertheless shot a wedding with it. I set the camera to AI servo and for each motif, I shot a burst of images (3 to 5). When looking at the results, I mostly found 1 sharp shot in 5. Somtimes 2, somtimes none. Thus I still got many lovely photos, but at the price of having to spend extra time to sort out many soft frames. I will not do it again, unless Sigma is able to fix the problem. I phoned them and they asked me to send in the lenses and the camera. They said they can fix the inconsistency. I am not sure about that. Has anyone had the experience with Sigma that their service was able to fix AF inconsistencies? If so, I'd like to hear it. I was considering buying the 1.4 85 ART, but I will only do it, if Sigma can fix the problem.


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## SecureGSM (May 4, 2017)

There is a new Sigma 135 F1.8 Art review by Lens Rental that was published back on the 24th of April 2017 that I have overlooked.

"... The autofocus is fast and incredibly accurate, the images are exceptionally sharp, and the bokeh is incredible. The Sigma 135mm f.1,8 Art Series takes everything I always loved about the Canon 135mm f/2L and surpasses it in every way..."

By Zach Sutton, Lens Rentals
Published April 24, 2017

__wordpress.lensrentals.com/blog/2017/04/lensrentals-reviews-the-new-sigma-135mm-f1-8-art-series-lens/ 

Question: "... Large aperture Sigma Art lenses live or die for many photographers based on the *consistency* of the AF, not the speed or its ability to be adjusted in the USB dock. A dock cannot correct an inconsistently focusing AF setup that 'whiffs' occasionally, as prior Sigma Art primes have done. Can you comment on the hit rate of the AF of this lens? How often does it miss a clear target?..."

Answer: Zach Sutton Photography

"...I had absolutely no issues with the AF accuracy of the lens. I found it to be fast and accurate even when using it on moving subjects. When using it outdoors, and *on a moving subject while I was moving*, it seemed to hit focus *95%* of the time* in AI Servo*, which is every bit as good as anything else I've used..."

P.S. My Sigma 1365 F1.8 Art arrived today. I will be giving the lens a good AF work out over the coming weekend shooting the Reikan Focal target in a controlled environment and promise to report the AF rate results back to forum.


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## AcutancePhotography (May 4, 2017)

You guys must be unlucky. I have not had any problems with my new Sigma Art lenses. I have not purchased the 135 yet, but when the bank account is agreeable, I would not hesitate to buy another Sigma.


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## ahsanford (May 4, 2017)

Disappointing to hear Eldar's experience.

I still await a proper technique- and subject-independent means to look at the hit rate on this: Randomly defocused lens + Shot @ f/1.8 + tripod + AF on the center point aiming at a static high contrast target. Rinse and repeat 50 times. That should represent the best the lens could possibly do. If it randomly whiffs more than (say) 1-2 shots in 50, the lens is DOA for me.

The 85 Art was supposed to have solved this with more powerful AF motors, if I recall, and that lens has received very strong praise from an AF consistency standpoint. How this one did not follow suit is surprising.

So if I have this right:

14 Art = No reviews yet (but that FL is pretty forgiving AF-wise)

20 Art = Haven't heard much from folks on this one (but that FL is pretty forgiving AF-wise)

24 Art = Haven't heard much from folks on this one

35 Art = Some folks are lucky and its perfect, but many have experienced AF inconsistency

50 Art = Some folks are lucky and its perfect, but many have experienced AF inconsistency

85 Art = Pretty terrific consistency-wise from those who have deliberately tested for that

135 Art = Still awaiting a proper look from reviewers, but Eldar's findings are troubling


For the record, *I want Sigma to succeed*, but I often cannot chimp & reshoot. So the AF randomly whiffing is a _lost moment_ to me, and that's DOA. I need to be confident in the AF of a large aperture lens, and I'll stick to L glass until Sigma gets its act sorted out.

- A


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## jolyonralph (May 4, 2017)

The Sigma 35mm Art was, for me, the most disappointing lens purchase ever. So much hype and so much potential, but totally unreliable in regular use. Thought the USB dock would help fix problems, that was another £30 down the drain.

No more Sigma lenses for me, ever.


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## Labdoc (May 4, 2017)

I bought the Sigma 50 1.4 Art after having a good experience with the 150-600 C. Out of the box it was front focusing on the 5DIV so I adjusted it. Now focus is right on center but I am disappointed in the sharpness even at f5.6. I really want a fast 50 mm and was reluctant to buy the Canon 1.2L with all the talk of focus shift and softness. The Sigma 50 Art is going back or getting sold and rethinking maybe the Canon 85mm 1.2L would be a better choice.


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## ahsanford (May 4, 2017)

Labdoc said:


> I bought the Sigma 50 1.4 Art after having a good experience with the 150-600 C. Out of the box it was front focusing on the 5DIV so I adjusted it. Now focus is right on center but I am disappointed in the sharpness even at f5.6. I really want a fast 50 mm and was reluctant to buy the Canon 1.2L with all the talk of focus shift and softness. The Sigma 50 Art is going back or getting sold and rethinking maybe the Canon 85mm 1.2L would be a better choice.



We need a new 50mm prime with a flat plane of focus and rock solid AF so badly it hurts. But that's for another thread (or twenty).

- A


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## Jopa (May 4, 2017)

Eldar, it sounds like a defective lens. The range should vary +/- 1 or 2 but not +/-14 
Just take another lens, and I'm pretty sure it will be fine. I had a similar issue with the 70-200 II recently, sent it to Canon and received it back completely fixed (0 AFMA on my 1dx2 and 5dsr). It can happen to any lens as far as I understand.
I will pass on the 135 art because it's just too long for me to shoot without IS, but my 85 art is in -7 to -5 range (i.e. +/- 2, depends on distance) which is acceptable, I could probably calibrate it further via the dock, but just don't have time for it. IMHO a bigger problem with the Sigma lenses is focus shift, especially noticeable for the off-center AF points. So... just give another lens a try.


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## Jopa (May 4, 2017)

ahsanford said:


> I still await a proper technique- and subject-independent means to look at the hit rate on this: Randomly defocused lens + Shot @ f/1.8 + tripod + AF on the center point aiming at a static high contrast target. Rinse and repeat 50 times. That should represent the best the lens could possibly do. If it randomly whiffs more than (say) 1-2 shots in 50, the lens is DOA for me.



What is your definition of "whiffs" ? PDAF variation is quite significant, if you're talking about slight focus changes - I think it can be easily more than 2-4%. I you meant full OOF - theoretically it shouldn't happen at all in the controlled environment / center AF point.


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## ahsanford (May 4, 2017)

Jopa said:


> ahsanford said:
> 
> 
> > I still await a proper technique- and subject-independent means to look at the hit rate on this: Randomly defocused lens + Shot @ f/1.8 + tripod + AF on the center point aiming at a static high contrast target. Rinse and repeat 50 times. That should represent the best the lens could possibly do. If it randomly whiffs more than (say) 1-2 shots in 50, the lens is DOA for me.
> ...



I'm not referring to imperfect focusing, I am talking about a clean whiff where the subject is hopelessly OOF.

Head to TDP's 50 Art AF review:
http://www.the-digital-picture.com/Reviews/Sigma-50mm-f-1.4-DG-HSM-Art-Lens.aspx

(find the butterfly postage halfway down the frame)

In focus: 1, 2, 5, 7, 8, 9
Slightly OOF: 4, 10
Somewhere between slightly OOF and a Whiff 6
Whiff: 3

It's only N of 10, but 60% correctly in focus -- in controlled conditions that leave subject movement, handheld, shutter speed, technique, etc. out of it -- is simply not good enough.

I could take 1 slightly OOF in 10 and perhaps 1 complete whiff in 50, but demonstrations like TDP's simply scream 'avoid' to me as a prospective buyer unless I'm only shooting MF or I'm in studio conditions where I can chimp and reshoot on the spot.

- A


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## LordofTackle (May 4, 2017)

Very sorry to hear that Eldar, especially given your already troubling experience with Sigma lenses...



ahsanford said:


> For the record, *I want Sigma to succeed*, but I often cannot chimp & reshoot. So the AF randomly whiffing is a _lost moment_ to me, and that's DOA. I need to be confident in the AF of a large aperture lens, and I'll stick to L glass until Sigma gets its act sorted out.
> 
> - A



Me too. I WANT to like them, especially since Canon prices seem to skyrocket lately. But so far, as you say, it's DOA. I tried a 50mm Art and it was all over the place. Not again. I was tempted by the 85 ART but luckily Canon announced theirs, so I will wait for that.  (and pay probably at least twice the price )

-Sebastian


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## snappy604 (May 4, 2017)

Sorry if duplicating any responses.

I have several Sigma PRIME ART lenses.. my 35mm 1.4 Art for Canon was giving me nutty inconsistent focus. Friend with the Nikon no issues. I even bought the USB Dock and it didn't help.

I noticed one day it was a bit loose mounting to the body and that it had wiggle space, explaining the focus isues. I had misplaced my receipts and wasn't wanting to be without the lens for a while, so I did some research on youtube of all places and found a video that discussed how to repair it.. basically you remove a few screws, tighten a couple of others and it mounts solidly! and it FIXED all my focus issues. Something to consider.

apologies if putting a hyper link is a faux pas. But this is an example of the video, I think at time I followed another. https://www.youtube.com/watch?v=gEBpq1_sYo0 

anyways something to think on.


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## [email protected] (May 4, 2017)

I have had very good luck with the four Sigma Arts I've owned. 

All of them but one required AF microadjustment BUT I did not do this in camera, but rather did it via the Sigma Dock. The Sigma Dock lets you give independent AF adjustments by different subject distances. 

I speculate that people merely using in-camera AFMA are not adjusting for all of the needed dimensions because it only allows for a single adjustment value for a prime lens. Yes, using the Dock with all of its additional variables is a pain, but yes, I've had it consistently work for me, and the results are worth it. 

You might have a bum lens, but you also might just need to dock it, and waste two hours of your life (it takes longer than FOCAL). 

I have not AFMA'd my 135 Art yet because it hasn't shown any need for it. It is fast and consistent. When I get around to it, I won't be surprised if I could make it even better, but right out of the box it's performing great.


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## ahsanford (May 4, 2017)

[email protected] said:


> All of them but one required AF microadjustment BUT I did not do this in camera, but rather did it via the Sigma Dock. The Sigma Dock lets you give independent AF adjustments by different subject distances.
> 
> I speculate that people merely using in-camera AFMA are not adjusting for all of the needed dimensions because it only allows for a single adjustment value for a prime lens. Yes, using the Dock with all of its additional variables is a pain, but yes, I've had it consistently work for me, and the results are worth it.



I appreciate the distinction between a single point with AFMA vs. a number of distances with a USB dock, but there are two different issues at play here:


Front- or back-focusing AF can be treated with their dock to good effect, and yes, Sigma gives a more comprehensive tool to dial that in as a function of distance.


Inconsistent AF in which the AF does not consistently hit the same target at the same distance is not dock correctable. Again, see my TDP reference -- no dock on the planet will solve that.

The second one above is the bit people are complaining about. There is ignorance about properly performing AFMA, I agree, but this forum is loaded full of pros and fairly well read enthusiasts that know the difference between the two, and even they are saying its an inconsistency issue (as are reviewers).

So I'm glad you've had good luck with your Art lenses, but that has not been everyone's experience.

- A


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## Jopa (May 4, 2017)

ahsanford said:


> I'm not referring to imperfect focusing, I am talking about a clean whiff where the subject is hopelessly OOF.
> 
> Head to TDP's 50 Art AF review:
> http://www.the-digital-picture.com/Reviews/Sigma-50mm-f-1.4-DG-HSM-Art-Lens.aspx
> ...



I see, and yes, it kind of sucks...  And that's exactly the reason why I'm avoiding the "old" Art lenses (prior the 85mm Art). I'm also wondering why is it happening? I bet the same "unstable" lens will work fine in the Live View / CDAF. Can someone explain please? If the distance to the PDAF sensor vs distance to the imaging sensor is the same or adjusted with AFMA, it shouldn't be any difference?


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## jd7 (May 5, 2017)

ahsanford said:


> So if I have this right:
> 
> 14 Art = No reviews yet (but that FL is pretty forgiving AF-wise)
> 
> ...



I do understand what you are saying here - but I question the statements that "some" have found AF on the 35 Art and 50 Art to be fine but "many" have had AF inconsistency problems. I'd give you "some" having had AF inconsistency problems, but without knowing how many lenses have been sold and how many have had problems, I think it's hard to say that "many" is correct. Certainly if you look around the internet you will find a number of people complaining, but I think it's fairly safe to assume that the people who are unhappy are far more vocal than the people who are happy. So the question is, for each person complaining, how many others are perfectly happy but just not talking about the issue on the internet?

I also cannot help but wonder if Sigma's reputation means people tend to jump to the conclusion that any problem with AF with a Sigma lens is the fault of the lens, without really checking whether there might be another cause. For example, I'm sure one of the CR regulars (cannot recall who) discarded a Sigma Art lens or two because of AF problems, but after buying a Canon prime discovered a similar problem which was eventually traced to the camera body.

I also wonder if some AF issues are really technique issues or simply unrealistic expectations in relation to shooting at very wide apertures. The price of the Art lenses has opened the door to fast aperture lenses to more photographers, I'm sure, and I'd guess may of them are not pros. Obviously, shooting at f/1.4 is a very different thing from shooting at f/4.

Anyway, please don't get me wrong, I have no doubt there are some "bad" Art lenses out there - it's clear there are people here on CR who are experienced with fast aperture lenses who have run into trouble - but I'm equally sure there are "bad" Canon lenses too. And I'm certainly not saying the Sigma lenses are perfect. I have 2 Art primes plus the 85 EX, and yes, I do see the occasional whiff. I don't have experience with the Canon L primes (sadly!), so I cannot compare AF error rates directly - although even if I could, the sample size would be so small you couldn't conclude much anyway. That said, for what it is worth (not much!), I had the Canon 35 f/2 IS before the Sigma 35 Art and I haven't noticed any different in AF consistency between my copies of those lenses. I get the occasional unexplained whiff with Sigma, but the Canon did that too. And I guess that is the point, at least to me: do the Art lenses really have a higher rate of AF inconsistency than comparable lenses from Canon or anyone else? It would be great to have some facts and figures to assess that, but we just don't have that information.


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## jd7 (May 5, 2017)

ahsanford said:


> I'm not referring to imperfect focusing, I am talking about a clean whiff where the subject is hopelessly OOF.
> 
> Head to TDP's 50 Art AF review:
> http://www.the-digital-picture.com/Reviews/Sigma-50mm-f-1.4-DG-HSM-Art-Lens.aspx
> ...



Again, point taken, however without a comparison with a comparable lens from Canon (or someone else) under the same conditions, the question is what we should conclude from those figures.

I noted that in the TDP review of the Canon 35L II, the AF was praised and any errors were put down to user error. As I recall though, the 35L II review didn't go into any details or provide any stats on AF misses. I'm certainly not suggesting any intentional bias, but it does make me wonder if Sigma's reputation has caused Bryan to focus on Sigma's AF more than otherwise (pun intended!!) and to conclude that errors are due to the lens, while more readily attributing errors with the Canon to user error. Without knowing exactly what Bryan was seeing I do not know the answer, of course. I really would like to see good stats though!


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## ScottyP (May 5, 2017)

My 35 Art workers great from the beginning. I did a simple inclined ruler AF test and put 2-point adjustment but it didn't really need it. I am happy. Maybe with a longer FL a small varianc might seem more relevant?


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## streestandtheatres (May 5, 2017)

I have a couple of ART lenses, though not the 135. I have found that FoCal does not work well with them. In both cases I get a bunch of inconsistencies. But in real world they are fine, once the right AFMA is dialled in. That, without FoCal, takes a bit of patience. But once I get the right setting both lenses are super reliable. Without the right setting they both tend to forward or rear focus, and to do so inconsistently.


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## [email protected] (May 5, 2017)

I appreciate the distinction between a single point with AFMA vs. a number of distances with a USB dock, but there are two different issues at play here:


Front- or back-focusing AF can be treated with their dock to good effect, and yes, Sigma gives a more comprehensive tool to dial that in as a function of distance.


Inconsistent AF in which the AF does not consistently hit the same target at the same distance is not dock correctable. Again, see my TDP reference -- no dock on the planet will solve that.

The second one above is the bit people are complaining about. 
- A
[/quote]

I think you are right to distinguish between those two potential flaws. I wonder, though, if the first could help cause the last. When you have things hinkey with the autofocus, my experience has been that things act much more inconsistently, especially at apertures <2. I speculate that the camera is attempting to determine a binary status (focused adequately or not) on something that looks fudgy due to back- or front-focus. 

A couple of my Art lenses - which are rock-solid now for both focus and consistency - required pretty different adjustments at different subject distances. When new out of the box, they'd appear to be hugely inconsistent, which turned out merely to be a factor of the diversity of the distances I was shooting. Not saying this is necessarily the issue with the OP and others chiming in, but hoping that perhaps some of them might find this is a cheap solution.


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## Eldar (May 5, 2017)

[email protected] said:


> I appreciate the distinction between a single point with AFMA vs. a number of distances with a USB dock, but there are two different issues at play here:
> 
> 
> Front- or back-focusing AF can be treated with their dock to good effect, and yes, Sigma gives a more comprehensive tool to dial that in as a function of distance.
> ...



I think you are right to distinguish between those two potential flaws. I wonder, though, if the first could help cause the last. When you have things hinkey with the autofocus, my experience has been that things act much more inconsistently, especially at apertures <2. I speculate that the camera is attempting to determine a binary status (focused adequately or not) on something that looks fudgy due to back- or front-focus. 

A couple of my Art lenses - which are rock-solid now for both focus and consistency - required pretty different adjustments at different subject distances. When new out of the box, they'd appear to be hugely inconsistent, which turned out merely to be a factor of the diversity of the distances I was shooting. Not saying this is necessarily the issue with the OP and others chiming in, but hoping that perhaps some of them might find this is a cheap solution.
[/quote]
I have not had the chance to return to the dealer, to give them a chance to fix the problem. I doubt that they will though. I have been running both FoCal calibration on multiple cameras (5DSR, 5DIV and 1DX-II) and manual attempts, using a LensAlign rig. I have also tried to do it on different distances from. However, the spread of focus is such that both FoCal and I are unable to determine an AFMA setting. A dock will not change this. 

It may well be that I have a poor copy (again), but it behaves exactly as the 35/1.4 and 50/1.4 Art lenses did. So I am not optimistic. However, if they fix it, I will still have a hard time using it for anything critical, because I simply will not trust it. Luckily I have alternatives.


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## Random Orbits (May 5, 2017)

I have one Sigma lens, the 20A, and so far I've only used it with the 5DIII. The focus with the center point is OK most of the time but not as accurate as the 24-70L II or the 35L II. My frustration with it comes to using the outer points (I primarily use the left and right banks) on subjects that are close. It consistently front focuses with the outer points but is mostly on in the center. The performance is similar using the left and right outer banks, so it's not a decentering issue. The dock wouldn't help with this. If the subject is farther, then it starts to fall into the DOF and the issue is masked.


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## SecureGSM (May 6, 2017)

*Eldar*,
I have completed calibrating my Sigma 135 F1.8 Art. I used Focal target and Focal in automated mode. camera:6D.
I also took my time to verify that caibration was valid for daylight and LED lighting conditions.
calibrated at 0.9m, 1.3m, 2.5m and 12m (infinitiy). Focal reported focus consistency no less than 98.5% through the test. In order to ensure focus consistency I then ran callibration test at each given distance 4 more times and Focal suggested very similar calibration adjustment values fluctuating around the best AFMA values and within -1/+1 AFMA units around the set value.
Lens is impressively sharp with maximum sharpness achieved at around 10m to target (near infinity) and equal to 2145 Focal units. My sharpest lens is Sigma 85 F1.4 Art with 2185 Focal units achieved at approx. 4m to target.
It is a sharp lens, not as sharp as my copy of Sigma 85 F1.4 Art. They both great lenses but produce very different images of course...


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