Sigma 30mm f/1.4 Focus Issues - including after calibration?

[DeirdreLLogan]

Hi guys,

I have a Sigma 30mm f/1.4. I use it primarily on a 7D (And often on a 60D, too).

The lens seems to focus perfectly, up to a certain distance (for argument's sake, we'll say 10 feet). Within that distance, the lens is generally spot on, sharp and get the focus right.

However, when I go above that distance, the lens seems to have real issues with missing focus. Sometimes it's right, vast majority of the time it's wrong.

So I sent the lens off for calibration with our Sigma dealer (who are fantastic to deal with so far) and I got it back today. Sigma dealer reckons there's a bit of front focus, which they believe they fixed. Said they took a few random shots and it should be grand now.

However, the lens still exhibits the same issues (now, i do genuinely believe that the Sigma guys think they got it right, as, if I were checking a lens' focus ability, I'd get really close to my subjects so the DOF would be shallower, so they probably didnt really try and distance shots at all, which is understandable).


I was wondering if anyone else has had this issue, and if so, have you had it fixed? Did you have to re-send for calibration again (I'm guessing I'll be needing to re-send with the camera bodies, but seen as the lens is spot-on under a certain distance, and exhibits similar traits on both bodies, I'm under the impression it's the lens at fault).


Anyone any experience of this?


Cheers

 

[Chapman Baxter]

My Sigma 35mm Art had a slight back-focus issue at longer distances, which I was easily able to fix with the Sigma Dock. The dock's software allows you to calibrate focus at four separate distances (three at the more critical short distances and one from about a metre to infinity). Assuming the 30mm is compatible with the dock, I'd recommend giving it a go.

 

[Thomas Lieser]

I guess you are talking about the old lens without HSM? I have that lens -- my camera is a 50D.

I do love it for close ups and concert shots (high contrast, available light) -- not to far from the subject. I use it wide open (1.4 to 1.8) because after that it starts to shift terribly.

What you experience seems to be just the behavior that my lens exhibits.

I do love it though for the shots it take with it

 

[GammyKnee]

OP, do you mean the Sigma 30mm f/1.4 DC HSM A (recent) or the older Sigma 30mm f/1.4 EX DC HSM?

If it's the older one, then I had that for about 4 years before I went full frame. Having read about its reputation for unreliable AF, I actually bought it second hand from someone who insisted that his copy was a "good'un", hoping to bypass the whole return/repair cycle. For the most part the lens was indeed pretty good, and certainly I really enjoyed using it.

My copy was unusably (to me) soft wide open even taking AF out of the equation so I typically shot stopped down to f2 or more. AF-wise, it was pretty reliable at relatively close distances (1-2m), after that it could occasionally throw me an inexplicably and wildly out of focus shot. But I stress the "occasionally" - certain light, contrast etc. Also I found it was not terribly good for tracking shots with AI Servo.

So the bottom line is that although my copy had its issues, it wasn't as consistently unreliable as yours appears to be.

 

[Mt Spokane Photography]

The problem with 3rd party lenses is that issues might be in the camera, or in the lens, or a combination of both. neither Sigma or Canon will do more than calibrate their product, and it still might not fix the issue.
The newer Sigma Art or Sport lenses have a optional calibration station, which allows for calibration to one camera. The second camera is out of luck, but if it has AFMA, then you should be able to get it close.
Its tough for a third party lens maker to get a perfect product. The lens must emulate a Canon lens by sending a code to the body. The body may then use that data to make come adjustments.

Considering how complex it is, its surprising that third party makers like Tamron and Tokina do so well with the AF. (They have had a few issues as well)

Sigma has struggled over the years with faulty reverse engineering of the Canon AF system, some of their earlier lenses will not work on DSLR's at all. This also includes rebadged names like some Quantaray lenses which were made by Sigma. They are just paperweights, because the aperture does not work and they return error 99. A few of them could be fixed, but many could not.
Things are better with the newer lenses, but they still often need calibration to a specific camera model. I do not think that its a matter of quality control, but one of the difficulty in turning out a lens that will autofocus accurately across all Canon models.

 

[Arty]

These AF problems are specific to Sigma fast, F1.4 lenses and some of their zooms. Sigma used to say on their website that you must have microadjust on your camera for their F1.4 lenses. I have two Tokina lenses and a Sigma 50F2.8 macro. None of these lenses, all F2.8, have any problems with AF on any of my current or prior Canon bodies.
The dock is an attempt to deal with these problems with AF at different distances and lighting.

 

[mrsfotografie]

OP, do you mean the Sigma 30mm f/1.4 DC HSM A (recent) or the older Sigma 30mm f/1.4 EX DC HSM?

If it's the older one, then I had that for about 4 years before I went full frame. Having read about its reputation for unreliable AF, I actually bought it second hand from someone who insisted that his copy was a "good'un", hoping to bypass the whole return/repair cycle. For the most part the lens was indeed pretty good, and certainly I really enjoyed using it.

My copy was unusably (to me) soft wide open even taking AF out of the equation so I typically shot stopped down to f2 or more. AF-wise, it was pretty reliable at relatively close distances (1-2m), after that it could occasionally throw me an inexplicably and wildly out of focus shot. But I stress the "occasionally" - certain light, contrast etc. Also I found it was not terribly good for tracking shots with AI Servo.

So the bottom line is that although my copy had its issues, it wasn't as consistently unreliable as yours appears to be.

I had a bad copy of the Sigma 30mm f/1.4 EX DC HSM, it was soft wide open, and it consistently missed focus at longer focal length. Manual focus, it was fine though and I love the bokeh this lens produces, there's just something about the images produced with this lens. My 50mm Sigma has a similar feel to it, but not quite so pronounced. On the other hand, my 50mm is a stellar performer so I'm happpy I kept faith in Sigma. I also have a very good 20mm f/1.8 which must really be a rare good copy if you believe the internet reviews. My 35mm again is a stellar lens - so no further complaints from me

 

[Arty]

What do you mean by "longer focal length" on a 30 mm prime?

 

[GammyKnee]

What do you mean by "longer focal length" on a 30 mm prime?

Given the context I'm sure she means that a misfocus became more and more likely as the distance to the subject increased.

 

[mrsfotografie]

What do you mean by "longer focal length" on a 30 mm prime?

Given the context I'm sure he means that a misfocus became more and more likely as the distance to the subject increased.

That's what I meant, yes.