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11-02-2008, 10:52 PM - 1 Like   #1
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Sigma 70-200mm loose on mount and not reporting name

So, I just got a Sigma 70-200mm lens. Fantastic, love it (see some pictures: https://www.pentaxforums.com/forums/post-your-photos/40897-my-2nd-studio-shoot.html)! But, I just noticed that it seems to be loose on my mount.

Specifically, the lens will rotate roughly 1 degree or so while on the mount. It doesn't come unlocked, it's just not tight like all my other lenses. What should I do? I bought it new off of eBay, I suppose I could try working it out with the eBay dealer, or should I send it to Sigma to get it repaired?

Also, I noticed that Lightroom doesn't show the lens name, just the focal length and aperture. My Tamron 18-250mm properly reports the lens name. Is something else wrong here too?


Last edited by krypticide; 11-03-2008 at 12:13 PM.
11-03-2008, 01:23 AM   #2
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Try tightening the screws that hold the mount in place. If that doesn't solve the problem, the issue lies somewhere else.
11-03-2008, 04:56 AM   #3
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all cameras & lenses have a little play on the mount. it is the engagement of the locking pin into the lens slot.

I wouldn't worry about it too much unlesss it seems to be excessive.

check the dimensions of the slot in the lens base and look at your camera locking pin also.
11-03-2008, 06:14 AM   #4
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I've had a problems with my Sigma 100-300 for some time. Been thinking of sending it in to get it check but I hate to have it gone.
My mount just doesn't fit snug like the rest of my lenses. When I power up the camera with the SR on it will sometimes ask me to set it manually. Not getting a good connection with the contacts. But it does seem to have the info of the lens when I bring that up. The movement is ever so slight but it is enough to cause concern. I'll try tightening the screws and see if that does anything.

Krypticide, I wish I had an answer for you. I think I would try the couple things suggested here and if that doesn't help send it back for a replacement.


Last edited by OrenMc; 11-03-2008 at 06:30 AM.
11-03-2008, 07:26 AM   #5
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everyone please be careful

I see a lot of comments about tightning screws.

I think everyone needs to take a step back and think about the "looseness" it is NOT the screws holding the mount to the lens, it is the machining tolorances on the mount itself.

On the lens is an oval hole or slot, that accepts the lens locking pin. some lenses have this wider than others.

There is also play in the pin on the camera body, which needs to be considered.

then there are the clearances ans springs that hold the faces of the mounts together.

These all have tolorances, they have to other wise you would never separate lenses from bodies.

By attempting to tighten the screws, you run the risk of snapping them off, as they are probably held in with a thread locking adhesive. Unless the mount is loose to the touch from the lens, LEAVE IT ALONE
11-03-2008, 07:51 AM   #6
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My 70-200 came dangerously loose IMO at a recent concert I was shooting. I could move the mount wayy to far for comfort. It's always had a ltitle give, but not like this. I quickly found a screwdriver and fixed it right away. Haven't had an issue since.

Sometimes still, my lens will loose contact and will report --- in the aperture value. Quick wiggle and its fixed, but its quite annoying.

Last edited by Tyler; 11-03-2008 at 07:59 AM.
11-03-2008, 08:10 AM   #7
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QuoteOriginally posted by Tyler Quote
Quick wiggle and its fixed, but its quite annoying.
Exactly. Is this an issue with incorrect tolerances? Or should we just leave it as expressed earlier?
11-03-2008, 09:13 AM   #8
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QuoteOriginally posted by OrenMc Quote
I've had a problems with my Sigma 100-300 for some time. Been thinking of sending it in to get it check but I hate to have it gone.
My mount just doesn't fit snug like the rest of my lenses. When I power up the camera with the SR on it will sometimes ask me to set it manually.
Hmm, my Sigma 135-400mm is doing exactly the same thing.

11-03-2008, 10:07 AM - 1 Like   #9
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So here's a question: the aperture seems to read correctly as well as the focal length, but when I look at images in Lightroom, there doesn't seem to be any lens information. It just shows focal length and aperture.

With my Tamron 18-250mm, the lens name reads correctly. Does this have anything to do with the fact that the lens is new and somehow the name can't be read by my K10D? Or is it related to the loose mount?
11-03-2008, 10:12 AM   #10
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QuoteOriginally posted by krypticide Quote
So here's a question: the aperture seems to read correctly as well as the focal length, but when I look at images in Lightroom, there doesn't seem to be any lens information. It just shows focal length and aperture.

With my Tamron 18-250mm, the lens name reads correctly. Does this have anything to do with the fact that the lens is new and somehow the name can't be read by my K10D? Or is it related to the loose mount?
All lens info and focal length, focusing distance etc comes through the communications pin, I'll call it pin 7, the furthest away from the lens locking pin. If this pin does not connect, the lens probably does not autofocus either.

you can clean these pins with a soft pencil eracer, but make sure NOT to use the type which are hard and aprasive.

for people who have screws coming loose (I mean in the lens of course) you might consider a bit of removeable loctite, assuming the lens is no longer under warranty. If it is under warranty take it in and have sigma look at it.
11-03-2008, 12:08 PM - 1 Like   #11
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I contacted the seller about the loose mount. He tested the other 70-200mm he had in stock on a K200D, and said the mount was also a bit loose too. So I think I will just ignore it for now since it's not terrible.

HSM autofocus works just fine, there's just no information about the lens name coming into the file. If "pin 7" is not connected, what information is not communicated? Does anyone else have this problem?

Last edited by krypticide; 11-03-2008 at 12:16 PM.
11-03-2008, 12:22 PM   #12
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note not all sigma lenses correctly provide names.

my 10-20 shows up as "Tamron 35-90mm F4 or various Sigma models" It may be that they don't have this programmed to provide a name.
11-03-2008, 03:15 PM   #13
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Just called Sigma tech support. The techician was clearly Japanese, which is a good thing in my mind, but his English wasn't the greatest, so I repeated myself to make sure he understood me correctly.

He said that slight rotation of the lens while mounted is normal, given the clearance with the locking pin. He also stated that the 70-200mm (and maybe other Sigma lenses, not very clear on that) does not report the lens name to the camera, hence why I don't see it. It's too bad, but I can live with that.
11-03-2008, 03:45 PM   #14
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My 70-200 reports as Sigma 70-200 f2.8 EX DG (something like that ; ))
11-03-2008, 04:36 PM   #15
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QuoteOriginally posted by Tyler Quote
My 70-200 reports as Sigma 70-200 f2.8 EX DG (something like that ; ))
Argh, talk about a monkey wrench... Do you have the HSM version?
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