IS feature and camera body.

[kfuse]

Is there anything else the Camera body is doing to IS other than supplying power

through the contacts?

[jimstrutz]

Yes, it is turning IS on. That is not a simple matter of supplying the right contacts with power. All communication between body and lens is done via serial data exchange, and that data is what tells the little computer inside the lens to turn on IS. I'm sure it's a rather simple communication protocol, but it is more complicated than just applying power.

[kfuse]

I though about on/off, but the trigger can be shared with auto focus so it might not be proprietary to IS (if so, the IS should be able to turn on/off from camera side). I'm sure distance and lens info is communicated real time via some kind of protocol though. So, if the IS is not working properly, should I suspect faulty camera body as well as the lens it self? OR the camera body has nothing to do with faulty IS?

[awindsor]

Kazuaki,

 

IS can be turned on independent of AF. If you put a 2x TC on my 300/4 IS then you lose AF but retain IS. The was not the case with some of the older bodies (it doesn't work on my EOS 5 for example).

 

On all the bodies IS and MF work fine together.

[kfuse]

Thank you for all the response! I called B&H photo to ask about this and several their reps confirmed that IS feature is contained completely withing a lens, so there is no control from body whatsoever. So, if IS is not working properly you can rule out camera body as a suspect.

[mark u]

Which lens are you having a problem with? Some IS lenses are more prone to problems with their IS unit than others, and the nature of the problem varies. In any event, if IS is defective in your lens you will need to get Canon to fix it. If the lens is out of warranty that could be an expensive repair, so depending on the lens it may make more sense to get a different lens.

[jimstrutz]

Kazuaki, B&H sales reps aren't really the people to ask a technical question. But if you are having a problem with IS, I would certainly guess that the issue is in the lens, as that is where all the active parts are.

[brucecyr]

"I would certainly guess that the issue is in the lens, as that is where all the active parts are"

 

Especially if you can confirm the hypothesis with some additional data, like verifying that AF works perfectly when IS is shut off. Still I wonder if it might be worthwhile talking to Canon service and seeing if they will take both the lens and the body to verify your findings.

[kfuse]

Recently I got 70-200mmF4LIS from B&H and I found some issue on 200mm side, so I had to returned it. You can find more detail in my other posting "fuzzy focus" on Feb 17.

 

I don't know how many bad samples are out there but I was wondering number of reviews posted on BH site. This is rather popular lens, it is kind of odd to see just 2 very positive reviews there.

[brucecyr]

Vendor sites aren't a prime magnet for user reviews. OTOH, you always wonder how much the vendor might censor material, and OTOH there really isn't any interactive component. You see a bit more of this on Amazon.com, which has developed the infrastructure a bit better and seems to be the model that others copy. However, other types of interests do seem to have more extensive reviews, e.g., NewEgg.com.