Sigma 50mm f/1.4 AF issues - Fixable?

[JohnGoose]

I know there have been numerous posts on this subject all over the web, but I was wondering if anyone on this forum had first hand experience with Sigma's service dept. on fixing these issues.


I own a Sigma 50 1.4 which is still under warranty. The lens seems to suffer front-focus issues from MFD to approximately 10'. For closer subjects I need to dial in a MicroAdjustment of +20 on my 7D. Beyond 10' the lens needs no adjustments, and the +20 MA will cause the lens to back-focus. So depending on the distance/subject of my photo, I need to adjust the MA accordingly. Since I primarily use the lens indoors or for portraiture I have been able to live with it.


As Brian states in his review of this lens, my keeper ratecan bea little below average. But when it's on, it can produce gorgeous photos. I just loveit's low light capabilities, usability at f/1.4, and delicious bokeh.


I should note that I also have similar problems with my Sigma 150mm Macro, as well.It also front-focuses at closer focal lenghts. But I typically use manual focus for this lens anyway on closer subjects. And autofocus will get me very close, enough to fine tune it.


So my question is if any Sigma owners have had similar issues with their lenses and sent it to a service center for calibration.Did this fix the problem? If they calibrate the lens for closer focal lengths, will that throw off the focus for longer ones? Does Sigma know that their backwards engineering for a Canon mount lens is lacking? Is there a secret fix that they won't admitt to?


BTW.....I don't live too far from Sigma's Ronkonkoma service center. I could easily drive there with my lens and 7D body for precise calibration.


Sincerely,


John

[Sheiky]

Hey John,


I didn't send my Sigma 50mm 1.4 back.....yet...


After I did eliminate some front-focussing +7, my photos are spot on every-time and I'm very happy with the lens.


It does sound that your lens is way off though and yes it would never hurt you to send it back I guess? Also calibrate it to the sweet-spot for the the distance you use the most.


Also my Canon 100mm macro's AF is also spot on at close 1:5 - 1:1 distances, but for portrait-use of 2m(7 feet) and longer it front-focusses as well. That doesn't bother me, because it is mainly a macro lens for me.


Nowadays my girlfriend bought a 450D and she wants to use the Sigma as well, so that leaves me almost no choice to send it back for calibration. Please let me know what happened if you send it back sooner than I do []


Jan

[JohnGoose]

Thanks for the reply, Jan.


I would like to bring the lens in to Sigma some time this summer when I get some free time. Until then, I have e-mailed Sigma support on my issue and am awaiting a reply. I'll keep you informed.


By the way, when I purchased the lens last year, I went thru 3 copies. All seemed to have front-focus issues. Since my 50D had micro adjust capabilities, it didn't concern me too much. It wasn't until later I realized the problem fluctuated with focal length.


I recently upgraded to a 7D, and the Sigma has the same problem on this body, as well.


John

[neuroanatomist]

Seems like the [url="http://www.lensrentals.com/rent/sigma-50mm-f1.4-hsm/for-canon]comments by Roger at lensrentals.com[/url] might be relevant:


[b]<span style="font-weight: normal;"]

Roger&rsquo;s take[/b]Its become apparent through many tests and online forums that the Sigma 50 is a &lsquo;special&rsquo; lens. I was glad to find this out because it was driving me nuts. Its a very nice lens when you use it just right, with superb sharpness and smooth bokeh. But here&rsquo;s the summary:


1) It works very well on crop frame cameras and at middle (5 to 15 feet) distance, so its a wonderful indoor lens.
2) On full frame cameras and to a slight extent on crop frame cameras the lens exhibits what I will term &lsquo;schizophrenic autofocus&rsquo;: Closer than 5 feet it will front focus, further than 20 feet it will backfocus. This is not a calibration issue, its just how it is.

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[JohnGoose]

Thanks for the link. I can see I'm not alone. But unfortunately, that's not encouraging news.


Despite this, the question remains, can Sigma service address this issue?


Is there anyone out there who has had 1st hand experience with this "glitch" and sent their lens in for service??

[Sheiky]

I would like to bring the lens in to Sigma some time this summer when I get some free time. Until then, I have e-mailed Sigma support on my issue and am awaiting a reply. I'll keep you informed.

That would be great!

I went thru 3 copies

I only tried 1 copy and am absolutely happy with it, the quote from John(neuroanatomist) makes me wonder if I should take the chance to let Sigma calibrate it just so my girlfriend can use it on her camera. Perhaps it won't handle so well for me after that [:P]...hmm...

I recently upgraded to a 7D

Are you sure you've got all your settings right? Try putting off the extra sensitive focus crosspoints. Just remain with the main center focus point without any expansion of that point. That will give you the most reliable results, given that f1.4 is really really sensitive with that tiny DOF.



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Seems like thecomments by Roger at lensrentals.commight be relevant:

Do you think I should get my Sigma checked? I mean is it worth the chance? Given that it works perfect on my camera, just the 450D of my girlfriend wont accept it without some front-focussing which can't be calibrated.


Thanks guys,


Jan
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[neuroanatomist]

Do you think I should get my Sigma checked? I mean is it worth the chance? Given that it works perfect on my camera, just the 450D of my girlfriend wont accept it without some front-focussing which can't be calibrated.

Depends on your generosity. "If it ain't broke, don't fix it." But, since the 450D doesn't do AF microadjustment, it probably just means you'd need to re-adjust for your camera once you got it back.

[Sheiky]

Depends on your generosity. "If it ain't broke, don't fix it." But, since the 450D doesn't do AF microadjustment, it probably just means you'd need to re-adjust for your camera once you got it back.

That's exactly my problem...it ain't broken at all. Except no-one else can enjoy my lens. I don't mind to re-adjust my camera again, I'm just worried that the lens will function differently afterwards (instead of reliable inaccuracy). Hmm I'll sleep a few night over it since I don't really want to lose my lens for like 3 weeks or so...

[JohnGoose]

In the long run, I guess it doesn't matter too much at all. I really like the lens and won't be selling it. I will most likely bring my lens in to Sigma and see what they can do.


To be honest, I may be over scrutinizing. I'm not normally a pixel peeper. I never really pulled out my other Canon lenses and tested their AF capabilities and varying focal lengths. I just heard of this problem with the 50 1.4 and decided to probe further. I'm sure a lot of the OOF shots I've taken can just as easily bedesignatedasuser error. But Ido expect my equipment tofunction optimally. After all, we paid enough for it, right?

[Sheiky]

You're right John. I'm also very happy with it and to be honest my Canon 100mm macro also front-focuses quite a bit in portrait distances. But for the macro work where it's designed for it shines! So I'm not complaining [H]