Woe and Pathos in the Sigma 50 Art?

[AcutancePhotography]

Now I'm wishing Canon had a dock!!!

I imagine that soon all the lens manufacturers will have some connection, either a dock or a built in USB. Or maybe just a pass through using the camera hooked up to the computer.

But in any case a lens to computer link may become more common in the future.

 

[NancyP]

Yes, the dock makes sense, particularly for a third-party manufacturer without access to the exact AF protocols used by each camera. That said, my 35 Art has been fine, though admittedly much of my wide-open use has been astrophotography, in which one focuses manually via LCD.

 

[Loswr]

Now I'm wishing Canon had a dock!!!

I imagine that soon all the lens manufacturers will have some connection, either a dock or a built in USB. Or maybe just a pass through using the camera hooked up to the computer.

But in any case a lens to computer link may become more common in the future.

Likely true for 3rd party lenses. For OEM lenses, connection via the body makes more sense, IMO. In the case of Canon, you can currently update lens firmware via the body (tethered or by loading the lens firmware on a memory card).

 

[BLFPhoto]

Eldar, since you use FoCal and claim this lens has inconsistency issues, perhaps you'd care to share some focus consistency test results from FoCal on this lens with us. Multiple copies, multiple bodies would be indicative. At least post the charts showing the 10 or 20 shot tests, with the final percentage.

 

[Eldar]

I have not saved many files from my FoCal runs, but I have this. To compare I also added a run with the 85 f1.2L II. Judge for yourselves.

 

[privatebydesign]

Eldar, since you use FoCal and claim this lens has inconsistency issues, perhaps you'd care to share some focus consistency test results from FoCal on this lens with us. Multiple copies, multiple bodies would be indicative. At least post the charts showing the 10 or 20 shot tests, with the final percentage.

There are few people I trust implicitly on this forum, Eldar is one.

 

[Eldar]

Eldar, since you use FoCal and claim this lens has inconsistency issues, perhaps you'd care to share some focus consistency test results from FoCal on this lens with us. Multiple copies, multiple bodies would be indicative. At least post the charts showing the 10 or 20 shot tests, with the final percentage.

There are few people I trust implicitly on this forum, Eldar is one.

Thanks Private.

This was 50 Art copy no.2. No.1 was worse. I believe it is fairly easy to see that this focus issue has nothing to do with AFMA being wrong or being visible because of how sharp the lens is. It is totally inconsistent and this lens (and the one before) should never have left the production plant in the first place.

 

[DominoDude]

Eldar, since you use FoCal and claim this lens has inconsistency issues, perhaps you'd care to share some focus consistency test results from FoCal on this lens with us. Multiple copies, multiple bodies would be indicative. At least post the charts showing the 10 or 20 shot tests, with the final percentage.

There are few people I trust implicitly on this forum, Eldar is one.

Thanks Private.

This was 50 Art copy no.2. No.1 was worse. I believe it is fairly easy to see that this focus issue has nothing to do with AFMA being wrong or being visible because of how sharp the lens is. It is totally inconsistent and this lens (and the one before) should never have left the production plant in the first place.

Firstly, I must add that I agree on the high credibility mentioned by PrivateByDesign. It is highly valued that you always can be depended upon to deliver sensible information and facts, Eldar.
Even though I don't have the Art-version of the Sigma 50, this is totally in line with the behaviour I've seen from the older 50/1,4 EX DG HSM. Undoubtedly sharp and crisp, but you can't predict (unless you use LiveView 100% of the time) if you will get any keepers.
The amounts of AFMA needed will change so much, and so often, that you can't even rely on the 1st shot directly afterwards to be in focus. All focus points having a tendency to need a different amount of adjust in comparison to all others isn't exactly making usage of these lenses any easier.

 

[YuengLinger]

Eldar, thanks again for your logical, thorough approach to evaluating your copies of the 50mm Art. You were one of the first members to post about your experiences.

At this point, we've pretty much come to the end of what can be done with the current version of the firmware. Either there is a problem with QC of the Sigma, or there is some elusive variable within Canon bodies, especially, it seems, the 5DIII.

Sigma has released some firmware updates this month, and from what I remember, the 35mm Art got its firmware update within about the same amount of time after release as we are in now for the 50mm Art.

So, my hope is eternal and my fingers are crossed. Lets see what the update brings.

 

[Eldar]

I have to admit that I have a Nikonrumors user account :. I got one to see how they reported on this lens. There are less posts about AF problems, but there are some who report exactly what I have found. I also tested on both 5DIII, 1DX and 5DII. I could not see any particular change in consistency (or lack of ..)

 

[photennek]

Thank you all for this informative thread! Especially Eldar... I'm curious about these Sigma Art lenses, but such a newbie that this is the first time I became aware of such quality issues.

Sigma has released some firmware updates this month, and from what I remember, the 35mm Art got its firmware update within about the same amount of time after release as we are in now for the 50mm Art.

So, my hope is eternal and my fingers are crossed. Lets see what the update brings.

Did the firmware update help with the 35mm Art lenses?

 

[wickidwombat]

my sigma 50 is the most amazing 50mm i have ever used in servo mode
hit rate is very high but i do only use the 5 double cross points on the 5dmk3

 

[[email protected]]

Eldar, sorry for your frustration. I've owned three of the Art lenses (50, and two 18-35s) and found that I shared your frustration when trying to AFMA with in-camera adjustments. After I got the dock, and could adjust at multiple distances, it really was night and day.

I don't know the mechanics behind this, but these Art lenses can be made to be sharp with Canon AFMA only at one distance, or at best two distances with the new cameras. You would think that - like with Canon lenses - adjusting for one distance would apply for the most part pretty well at other distances. This is not the case with these strange Sigma lenses. There is not a direct relationship between a correction at one distance and the remaining error at another distance. It's a more complicated mathematical relationship than that. Reminds me of having to do hyperbolic curve fitting for some forestry applications. You get a feel for it after a while, and you can figure out from a few data points that you're not dealing with one type of curve/formula, but another quite different one. I definitely had that spidey sense when trying to use AFMA on these guys.

The dock, when adjusted at all of the focal distances, really works. Yes, they should include the damned thing with the lens. And, yes, they should have it adjusted before it leaves the factory. I have NOT found that my other bodies are so different that once I adjust the Sigmas with the dock, another body will be wonky with the lens. In fact I can use AFMA to make a camera adjustment off of the already-dock-adjusted lens, and it works beauty. This suggests to - albeit anecdotally - that Sigma could indeed make these adjustments at the factory.

I notice that most of the people who continue to have focusing issues are using in-camera AFMA. This doesn't seem to be coincidental. I think there should be a warning on the box telling people to go buy the dock and not rely on AFMA. -tig

 

[Eldar]

FYI, I have the dock and I did my best to put it to good use. But it never changed the inconsistency. How do you set a value, when the deveation from measurement to measurement goes from -15 to +15?

 

[wickidwombat]

FYI, I have the dock and I did my best to put it to good use. But it never changed the inconsistency. How do you set a value, when the deveation from measurement to measurement goes from -15 to +15?

are you having the issue if you only use the central points?
I think the unreliable issues are related to using the outer points

 

[Eldar]

FYI, I have the dock and I did my best to put it to good use. But it never changed the inconsistency. How do you set a value, when the deveation from measurement to measurement goes from -15 to +15?

are you having the issue if you only use the central points?
I think the unreliable issues are related to using the outer points

The FoCal test is done with the center focus point. I did not see more or less issues depending on which focus points/groups I used or did not use. Not it is returned and I rely on my manual focusing skills with the Otus.

 

[GaryJ]

Thanks Eldar for your work.I have just finished watching DPR interview with US Sigma Rep, he claims all lenses ,that is All lenses are checked for sharpness before despatch,from reading prev posts it would seem the testers need their eyes tested 8) 8)