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08-14-2009, 01:41 PM   #1
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Sigma 24-60mm - lots of spots on the front element

This is my lens, I'm sorry to say. See below for pictures.

It's my favorite modern lens, and I keep it on my camera most of the time. If my wife had her way, it would be on there ALL the time -- when she picks up the camera with a Takumar on it, she puts it right back down again. Her loss. Anyway...

None of my other lenses have this problem: very many, probably hundreds of little pin-head-sized dots on the front surface of the front element. For a while I thought they might be water spots from fog or mist, but they don't clean off at all, with brush, cloth, or Lenspen. Looking closely, it almost looks like the lens coating is missing from those spots, as they are brighter-looking than the surrounding glass.

I don't know whether they are affecting image quality -- maybe a bit. This lens is pretty susceptible to flare and glare anyway, and this may be making it worse. Pics are still plenty sharp and contrasty under normal conditions.

I have kept this lens in the best possible condition. I ALWAYS use the hood and keep the lens cap on when not in use -- the cap is on even most of the time while I'm carrying the camera around. So it's really inconceivable that any physical damage did this.

Has anyone else seen this before? On a Sigma or any other lens? I'm going to send it in for service, and I'm hoping it will be warranty service. But I'm afraid they're going to claim that I did something to it, which would be disappointing.

Here are the pics. The only way I could get the spots to show up was to have the sun reflecting right off the front of the lens, so sorry for the flare. Because the glass is otherwise perfectly clear and these appear to be just tiny spots of altered reflectance, they can't really be seen in a normally-lit photo.

And so, ugh, on to the pictures:







P.S. This is NOT an old lens. I bought it during the Great Sigma 24-60mm Discontinuation Blowout in 2008.

08-14-2009, 01:53 PM   #2
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It could be dust inside the lens behind the front element. Should be no big deal and not affect your pictures.

Phil.
08-14-2009, 02:10 PM   #3
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It's not dust -- there is a little dust I can see in addition to these spots (I'm used to dust, no big deal), but the spots are definitely on the front surface.
08-14-2009, 05:12 PM   #4
Damn Brit
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Have you contacted Sigma, you have a four year warranty on it.

08-14-2009, 05:25 PM   #5
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If you have a macro lens handy, take a picture of the spots. IF they look like microbubbles I would diagnose that the glue holding two elements is separating. I would go to Sigma if you have the warranty.
08-14-2009, 09:15 PM   #6
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I have had a very similar problem on my Sigma 70-200 EX DG II. I had speckles like yours on the inner front 2 elements, not on the front glass itself. I have some pictures but don't know where I put them. It was really weird - not dust, perhaps it was oil specks?

Either way I returned the lens to CR Kennedy who ended up sending it back to Sigma Japan for repair. They ended up replacing the damaged elements with new ones and now it's all good.

When I mentioned this in the forums in the past, someone suggested it could be the lens elements separating. Some lenses have glass elements constructed of two separate pieces of glass which are simply glued together. I doubt that is the case with yours, because yours is the outside front element that is affected.
08-15-2009, 07:33 AM   #7
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It appears to me as contamination. You may be able to use a lens cleaner (make your own). Take one cup of distilled water and add a very small drop of diswasher liquid, mix well. Damp a small soft cloth, hold the lens down and wipe gently. Do not saturate with the solution, damp only. Leave the lens facing down until dry, should only take a few minutes. When cleaned, do it again using only distilled water and clean cloth. If it does not work, take it to a camera store and have it done by a pro or send to Sigma. Years ago someone sprayed airfreshner while I was using my camera. The spray deposited on the lens due to temperature and static differences. It would not come off until I used the solution above.

Hope it helps.
08-31-2009, 02:06 PM   #8
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Mea Culpa

Heh.

I'm posting this update for posterity even if it results in some (deserved) ribbing.

Anyway, as Denis thought, it turned out to be simply contamination. Tough stuff to be sure -- neither a dry lens cloth nor a Lenspen did a darn thing. I thought the Lenspen was supposed to rub those kinds of spots away!

But a gentle wet cleaning with a very mild distilled water and detergent solution cleaned it right up. It's now flawless. This weekend I tried to remove an already-removed lens cap and smudged the front element with my sweaty, greasy, sunscreen-covered thumb -- who among us hasn't done this? So It needed a good cleaning and it got one. Lo and behold, all my spots disappeared.

Thanks, everyone, for the input.

08-31-2009, 02:16 PM   #9
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Got the same problem with a 70-200mm f2.8
look like tinny air bubble under the front lens element.
Would like sigma Quality comtrol to be better.
marc.
08-31-2009, 03:58 PM   #10
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QuoteOriginally posted by Quicksand Quote
Heh.

I'm posting this update for posterity even if it results in some (deserved) ribbing.

Anyway, as Denis thought, it turned out to be simply contamination. Tough stuff to be sure -- neither a dry lens cloth nor a Lenspen did a darn thing. I thought the Lenspen was supposed to rub those kinds of spots away!

But a gentle wet cleaning with a very mild distilled water and detergent solution cleaned it right up. It's now flawless. This weekend I tried to remove an already-removed lens cap and smudged the front element with my sweaty, greasy, sunscreen-covered thumb -- who among us hasn't done this? So It needed a good cleaning and it got one. Lo and behold, all my spots disappeared.

Thanks, everyone, for the input.
Glad it all worked out for you.
08-31-2009, 04:35 PM   #11
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QuoteOriginally posted by Quicksand Quote
Heh.

I'm posting this update for posterity even if it results in some (deserved) ribbing.

Anyway, as Denis thought, it turned out to be simply contamination. Tough stuff to be sure -- neither a dry lens cloth nor a Lenspen did a darn thing. I thought the Lenspen was supposed to rub those kinds of spots away!

But a gentle wet cleaning with a very mild distilled water and detergent solution cleaned it right up. It's now flawless. This weekend I tried to remove an already-removed lens cap and smudged the front element with my sweaty, greasy, sunscreen-covered thumb -- who among us hasn't done this? So It needed a good cleaning and it got one. Lo and behold, all my spots disappeared.

Thanks, everyone, for the input.
you might want to consider a filter, it is worth the heartache of thinking your lens is ruined, and it may help a little with flair because the lens hood for this lens is designed to be used on a full frame camera and is undersized for the ASP-C format
08-31-2009, 04:38 PM   #12
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You didn't sneeze on the lens did you?
08-31-2009, 04:41 PM   #13
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QuoteOriginally posted by Damn Brit Quote
You didn't sneeze on the lens did you?
would that constitute a biological waste hazard?
08-31-2009, 04:51 PM   #14
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QuoteOriginally posted by Damn Brit Quote
You didn't sneeze on the lens did you?
Dunno 'bout you, but I usually point the lens in the OTHER direction.
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