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Old Apr 8, 2006, 11:33 AM   #1
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i have a Sigma EX 80-400 lens for my 30D, and have noticed a couple of things that i'm not sure whether to worry about or not.

first of all, there's a bit of rotational play between the lens and body when it's mounted, perhaps half a millimeter or so. is this a problem?i suspect this is an issue more with the body than the lens, because my Tamron 24-135 does the same thing. i'm used to the very tight, zero-play lockup of the lenses on my old Pentax ME Super, and though i know a small amount of rotary play is okay,how much is too much?

second, and perhaps of more concern, i've noticed that sometimes, during focusing, the image will "twitch", and i can feelsomething move inside the lens, almost like it got out of alignment a bit, and is moving back into place with a clunk. it only happens occasionally,but it seems to occur regardless of focal distance, whether the camera is on a tripod or handheld, etc.the lens functions beautifully in all other respects. is this something loose? a manufacturing defect? i've had the camera a bit over a week, and it's done this pretty much since day one.

thisis thefirst AFSLR i've owned, so i'm not sure what's "normal" for these things...
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Old Apr 8, 2006, 12:32 PM   #2
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Hi Squirl033,

Not sure if I can help you or not.

1. I find and found my Canon 28-135mm (and other lenses) to be tight enough on my Canon 350D / XT camera. Just tried to move it a bit (using "very moderate" force). It only moves a fraction... but that's only if I really try it. In other words it won't ever move "by itself", so I think it's nothing to worry about. I guess / hope it's the same with your set up.

2. I'm not certain, but maybe that "image twitch" syndrome is to do with the image stabilizer (optical stabilizer) on yourlens? (does it happen with your NON OS / NON IS lens too?) Just my $0.02.

Paul
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Old Apr 8, 2006, 1:18 PM   #3
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hi Paul,

no, it only happens on the OS lens... i kinda thought it might be something to do with the stabilizer, but i don't know. i never had that happen with my FZ20. like i said, thelens takes wonderful pics.... http://www.stevesforums.com/forums/v...mp;forum_id=11
i just don't know if that little clunk in there is normal for the Sigma OS lenses or not. i know there's a lot of glass in there - the thing weighs over 4 pounds - and it's possible the stabilizer is moving enough weight to make it do that. i just worry that if it is a defect, and i don't know it, it might haunt me later... the thing has a 4-year warranty, so that's not a concern, but for $1000, i'd like to know it's working properly!
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Old Apr 9, 2006, 5:50 PM   #4
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Well hope nothing is defect with it. But do let us know either way (that will let other people on the forum have the info too).

It can sure make great photos: again well done!

Paul
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Old Apr 9, 2006, 8:52 PM   #5
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Concerning the clunk, do you have the camera set to AI Servo? In this mode auto focusing can be quite jittery and can make noises at the same time.
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Old Apr 9, 2006, 10:32 PM   #6
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spy wrote:
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Concerning the clunk, do you have the camera set to AI Servo? In this mode auto focusing can be quite jittery and can make noises at the same time.
i've noticed it mostly in AI focus mode. i haven't used servo much yet...
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Old Apr 10, 2006, 10:28 AM   #7
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If your viewfinder also 'jerk' to re-adjust, the clunking noise could be the Optical Stabiliser at work...
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Old Apr 10, 2006, 11:05 AM   #8
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NHL wrote:
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If your viewfinder also 'jerk' to re-adjust, the clunking noise could be the Optical Stabiliser at work...
yes, the image in the viewfinder does twitch at the same time... it's really a very faint noise, and the twitch isn't a large movement, so i kinda figured it might be the OS mechanism, but i wasn't sure.either way it doesn't seem to affect the photos any!
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Old Apr 10, 2006, 11:23 AM   #9
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Yeap - my two IS lenses do the same the 28-135 IS is louder though since it's a non-L...
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Old Apr 10, 2006, 9:40 PM   #10
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could it have anything to do with the fact the lens doesn't lock up completely tight? as i mentioned above, there's a half-mm or so of rotational play in the lens... is there a way, short of returning the lens and getting a new one (which might not make any difference) to make the lens fit absolutely tight on the body?

i guess i'm just spoiled by the IS in my FZ20, which is absolutely silent...
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