oscillation in 28-138 IS lens?

[henry_minsky1]

I tried out a 28-135 IS lens at a photo shop, on my Digital Rebel,

and I experienced some sort of oscillation under some circumstances,

the lens seemed to vibrate all by itself in some sort of positive

feedback loop. I don't think the autofocus was involved, but it

might have been some feedback between the IS and autofocus perhaps.

 

The lens was pretty beat up, it was the one they had on hand for

people to try out, and had a definite shaky feel to it, so I am

wondering if this was just a loose mechanical problem or if other

people have experienced this kind of oscillation with this lens.

[digitmstr]

I used that lens for about 2 yrs. IMO, it does have a cheap feel to it but, I have never experienced the oscillation you speak of...

[PuppyDigs]

It's impossible to say for sure if it is abnormal without trying the thing out myself--words fall short. However, all IS mechanisms oscillate interior elements by design. That's how IS counteracts your shaky hands. Although slight, I can feel IS oscillation in my hands from both my IS lenses, including the EF 28-135 IS USM. It continues for a few seconds after you release the shutter button.

[henry_minsky1]

I could see through the viewfinder it looked like the image was vibrating, which definitely seemed wrong. I was thinking it might be some interaction between the autofocus and the image stabilizer, i.e., when the autofocus moved, maybe there was some slop in the mechanism which kicked in the IS which then knocked the autofocus

out, which then started a loop or something.

[ribook]

Who can say for sure? And it really doesn't matter because if you experienced what you think you experienced it's because you had a bad example--one that has had the snot beat out of it as a demo. If you buy a new or slightly used version of this lens, it will work as it should and you will not be disappointed.

[PuppyDigs]

<BLOCKQUOTE><I>"I could see through the viewfinder it looked like the image was vibrating, which definitely seemed wrong."</I></BLOCKQUOTE> <P>This quote is from page E-8 of the EF 28-135 IS USM Instruction Manual:</P> <BLOCKQUOTE>"...it will take about one second for the image stabilizer operation to stabilize. Look through the viewfinder to check that the image has stabilized before shooting. The image in the viewfinder may shake after the shot is taken in certain cameras. This [shaking] does not effect the quality of the photograph."</BLOCKQUOTE> <P>Like I said above, IS works by shaking an optical element to countact your hand shake, so an observant soul will notice the shake. With my A2 in low light I almost get seasick as it both shakes and "drifts." With my Elan 7E or 10D I barely notice the shake most of the time. Anywho, IS is a proven and mature technology and works great with only a little technique and common sense.</P

[eosdoc]

I think that viewfinder shake is a different phenomenon.

<P>

The "shake" that is visible in the viewfinder is a single event, and is not

an "oscillation". When I put my EF 28-135 IS USM lens on my EOS 1000FN,

shooting with the popup flash causes a "tilt" rather than a "vibration". See:

<BR>

<a href=

http://eosdoc.com/manuals.asp?q=IScompat

>http://eosdoc.com/manuals.asp?q=IScompat</a>

[jean_berthe]

My wife has a 28-135 IS since 1999. We only used it under this fashion: focus, recompose, shoot. Sometimes, the IS would not like this and after two years of �gentle� usage, it started to shake violently and to make loud grinding noise (only with the ElanII). I send it to Canon, with my ElanII, not knowing if it were the camera or the lens. They fixed the lens by replacing the servos for $250(Can). Been OK since then.

 

It�s a good lens but I would not buy the one your played with.

 

Good luck