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Old Sep 30, 2005, 10:27 PM   #1
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I bought my 1st DSLR yesterday, a Canon 350D with the 18-55 kit lens. I've noticed that focusing on an object (AF, full auto,zoom), there is a slight diagonal movement of the image frame visible in the viewfinder. Sort of like a to and fro diagonal jiggling as the lens ring rotates to acquire focus, from a previous setting. When I remove the Canon UV filter I've attached, the magnitude of movement decreases (less inertia due to less weight?) but is still perceptible.

Is this normal? Or is this suggestive of a defective lens?
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Old Oct 1, 2005, 8:25 PM   #2
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It's my 1st time to have a DSLR so I'm not sure if this sort of slight movement is normal or not:? Anybody with a 350D/ Rebel XT whocan help out and let me know if they experience this too or not? Thanks
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Old Oct 2, 2005, 12:47 AM   #3
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I've have the xt with the kit lens for a bit. I don't think I've experienced it.

Either that, or i haven't noticed....

you know how the focusing ring (that tiny ridged ring at the end) is kind of wobbly, right? you can move the ring side to side to see... It might be your kit lens wobbles a little while focusing. Try looking through the viewfinder and wobble the focusing ring a little. If it's the same type of frame movement... then (i think) it's not really a serious issue... it's just the cost effective build of the lens.
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Old Oct 2, 2005, 1:54 AM   #4
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Yes Boy, that might be it. On maximum zoom, the front lens focusing ring extends farther forward andis more prone to move or "wobble" laterally. So maybe when the ring jerks around to lock on focus, the inertia of movement causes it to slightly jiggle, causing some movement in frame? But is is normal or acceptable behavior for brand new lenses? Can there be variations in "wobbleness" between lenses of same specs (EF-S 18-55)? Or could mine be slightly out of whack?

I also wonder why the movement is more noticeable on vertical orientation? It's really there. I can appreciate it more by focusing on a painting frame where I can visualize the vertical edges and corners very slightly shift in position upon end of focusing.

Can the other 350D owners comment also if you've noticed this? Or am I just being too anal and paranoid about it? Thanks again
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Old Oct 2, 2005, 7:14 AM   #5
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dockiks wrote:
Quote:
Can the other 350D owners comment also if you've noticed this? Or am I just being too anal and paranoid about it? Thanks again
It's not the camera! :idea:

My EF 28-135 IS USM came with that 'feature' as well since the front elements are now so loose over time - Most folks don't notice this frame movement because the lens focusing ring is around the barrel behind the zoom ring instead on this lens which is firmly attached to the body, but when I use a polarizer I saw it all the time since one can 'wiggle' the front element quite easily

It's quite confusing at time since this lens IS can also moves the frame in the viewfinder! :O


This is one of the reason as to why the more 'experienced' folks look for internal zooming / internal focusing in their zooms design... The entire lens is whole with no bellowing effect especially with plastic material with tend to get loose over time. The EF 28-135 IS USM is internal focus, but its zooming mechanism is not and suffer from this 'play' when it extends in and out - On the more expensive lens like the 100-400L there's a rotating mechanism to 'tighten' the sliding barrel from occuring so at least some thought is given to it by the lens designers
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Old Oct 2, 2005, 3:01 PM   #6
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NHL: your comment is similar to what BoYFrMSpC mentioned, regarding the "wobbliness" of the focus ring, but at the same time, is quite different since your lens has internal focus so the front end doesn't oscillate during AF. I wonder if there are other XT/350D users who can comment whether they share my observations or not?

Cheers
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Old Oct 19, 2005, 11:51 AM   #7
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Just wanted to give an update about my XT's problem. 2 days after my
post, I brought it to Canon and compared it with their demo unit.
Their's also had a very slight movement, but markedly less compared
to mine. They took it back, and arranged for replacement through the
retailer. When I went to get it, the 2 units in the store also had
minimal movement so I refused to get either one. On my 2nd visit
today (2 weeks since I returned original unit!), both units still
had image movement, so I just finally decided to get the one with
less movement. So, from my observation of 5 brand new units, all
displayed the same image shift on AF on vertical orientation,
although the magnitude of movement varied among them, from very
noticeable to minimal. So I guess that this behavior is "par for the
course" for the 18-55 kit lens. People probably just don't notice
it, unless they really look for it. But as I've said before, as long
as it works and doesn't affect image quality, I can live with it.

KIKO
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Old Oct 20, 2005, 11:53 AM   #8
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I wouldn't worry about it... I borrowed an older 28-70 f2.8 L that had a slight amount of wobble at times.
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