emair
Topic Author
Posts: 95
Joined: Thu Sep 14, 2006 11:12 pm

Sigma Lens Problem

Sun Jun 20, 2010 2:09 am

Hey everyone,

I am having some trouble with my Sigma lens, 170-500mm.

When I put full zoom and I am trying to get a far target I am not able to focus (manual and auto). However, when I put full zoom, so 500mm, and I am trying to get a close target it does focus (manual and auto). It used to work fine, I am having this issue since the start of May. What is the problem? anyone has an idea?

Thx for the help.
Emanuele
  
 
dazbo5
Posts: 2717
Joined: Tue Mar 29, 2005 8:05 am

RE: Sigma Lens Problem

Sun Jun 20, 2010 10:47 am

Hi Emanuele,

I have a similar problem on the 50-500 where it won't focus between 200-300mm at certain times. The lens will focus at close distance, but not far targets. The lens has been back to Sigma 3 times, and they still haven't fixed the problem. They say it's to do with the auto focus motor and have re-calibrated everything on 3 occasions, but the problem soon comes back so I just live with it. Your problem sounds similar. In my case, it seems to only be a problem when the lens is used on cold days, it's fine at the moment with it being the summer so work that one out! If you have a problem, and especially if the camera is under warranty, I would send it back to Sigma to see what they say. They charged me £75 the first time I sent the lens back but all work after was done under warranty as the first time didn't fix the problem.

Good luck, I hope you have more luck that I have!

Darren
Equipment: 2x Canon EOS 50D; Sigma 10-20 EX DC HSM, 50-500 EX APO DG, Canon 24-105 f/4 L, Speedlite 430EX
 
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JohnKrist
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RE: Sigma Lens Problem

Sun Jun 20, 2010 11:21 am

Sigma just announced this week that they have focus problems with some lenses. I only got this via a Swedish trusted source and it reads as follows: (translation by me)

Quote:
Sigma has issued a call back for some of their zoom lenses as a problem with the auto focus have been found. If you think that your lens might be among those affected by the error check the lens ID-number:

Lenses that might have an AF error are::
APO 50-500mm F4.5-6.3 DG OS HSM (ID# 10633051 to 10972000)
120-400mm F4.5-5.6 DG OS HSM (ID# 10574001 to 10972000)
150-500mm F5-6.3 DG OS HSM (ID# 10674301 to 10972000).

Sigma advices anyone owning a Sigma tele zoom to check their ID-number to see if they have one of these lenses.
The company also states that anyone affected should contact Sigma to receive a free of charge repair/service to their lens.

End quote

So Darren, you might be able to get your 75 quid back if your lens fits the description.
Airliners.net Crew-Head Support
5D Mark III, 7D, 17-40 F4 L, 70-200 F2.8 L IS, EF 1.4x II, EF 2x III, SPEEDLITE 600EX-RT
 
dazbo5
Posts: 2717
Joined: Tue Mar 29, 2005 8:05 am

RE: Sigma Lens Problem

Sun Jun 20, 2010 12:08 pm

Quoting JohnKrist (Reply 2):
So Darren, you might be able to get your 75 quid back if your lens fits the description

Thanks, but my example is the previous EX version of the lens. It's interesting they've now finally admitted a problem though after all the trouble I've had. I just wish Canon would produce something similar as the 100-400 doesn't fit my needs. Having said that, the 50-500 is a good lens. Other then the focussing problem, it's served me well.

Darren
Equipment: 2x Canon EOS 50D; Sigma 10-20 EX DC HSM, 50-500 EX APO DG, Canon 24-105 f/4 L, Speedlite 430EX
 
dendrobatid
Posts: 1639
Joined: Sat Nov 06, 2004 3:40 pm

RE: Sigma Lens Problem

Sun Jun 20, 2010 12:32 pm

I used and liked my Bigma 50-500 until it got a knock and I had to send it back.
I notified my insurers but decided not to pursue the claim as the repair was quite reasonable. The problem was that the repair was poor and I had to send it back again and after a considerable delay too (at quite some expense to me). A second repair was also no good at which point Sigma said they would send it to Japan with no idea of a time scale or cost. I had been without the lens for at least three months by that time and I called my insurers who wrote it off and I bought a Canon 100-400 which I now prefer.
I am afraid that I was left totally unimpressed with Sigma after sales service though Bigma, especially now the OS version has come out, has a perfect range for aviation photography

Mick Bajcar
 
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dvincent
Posts: 1486
Joined: Mon Jan 01, 2007 9:53 am

RE: Sigma Lens Problem

Sun Jun 20, 2010 2:39 pm

It sounds like the lens is out of collimation and is not able to focus to infinity in relation to your camera. Likely the focus scale indicates that it's hit the end stop, way past the infinity mark but still cannot achieve infinity.

My 50-500 had this problem, same as Mick (after a knock and repair) and ultimately resulted in me getting rid of it. It too was an issue on cold days. Likely the lens elements in cold weather contract a bit, extending the lens' requirement to focus.

The way these lenses work is that the rear group moves forwards/backwards as a rear focus group. This is different from most lenses like 70-200s or the Canon 100-400L which use an internal focus mechanism which moves several elements in the central area of the lens construction.

This is not a problem unique to these Sigma lenses, by the way - nearly any rear-focusing lens could suffer from it. There's very, very few of those lenses around, though.
From the Mind of Minolta
 
emair
Topic Author
Posts: 95
Joined: Thu Sep 14, 2006 11:12 pm

RE: Sigma Lens Problem

Mon Jun 21, 2010 12:41 am

Thanks everyone for the precious inputs!

...at first I thought that was a problem due to the heat, because I noticed the problem while spotting in Dubai.

Emauele
  
 
dazbo5
Posts: 2717
Joined: Tue Mar 29, 2005 8:05 am

RE: Sigma Lens Problem

Mon Jun 21, 2010 7:38 am

Quoting emair (Reply 6):
at first I thought that was a problem due to the heat, because I noticed the problem while spotting in Dubai.

That sounds like excessive heat distrotion to me not allowing the lens to lock on to it's target. That happens so you may not in fact have an issue with your lens?

Darren
Equipment: 2x Canon EOS 50D; Sigma 10-20 EX DC HSM, 50-500 EX APO DG, Canon 24-105 f/4 L, Speedlite 430EX
 
emair
Topic Author
Posts: 95
Joined: Thu Sep 14, 2006 11:12 pm

RE: Sigma Lens Problem

Mon Jun 21, 2010 8:29 pm

I do have a problem. Because I have been using my lens in cold condition too lately and I still have this problem. I was just wondering when I said might be an issue due to the heat.

Emanuele
  

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