For Loupey - 300mm f/4-w/tubes on 40D

[Canon_Bob]

Hey Loupey,

Finally got a chance to test out the 40D/300 f/4 IS combo with tubes for you. I tried all kinds of variables (IS on, IS off, Mode 1, Mode 2, handheld, tripod, etc.). Bottom line, I had NO focusing issues of any kind. The only thing I did notice is that it was hyper-sensitive to movement, and the focus would re-sync if it detected any.

Here are a few from the test:

[Loupey]

Wow, C_B, thanks for taking the time to do this!

Sorry for the confusion, but I wasn't having an issue with the AF (I don't use that ). The problem is that the IS causes the image to "jump" just as the shutter is tripped and I can see the jumped image sliding back into position just as the mirror flips back down. This "swipe" of the image during the exposure is what is causing the smeared image.

Nonetheless, it is obvious that you are not encountering this problem so your test is still informative.

Looks like I will have to: 1) not use IS when I use this combo (not likely), or 2) use the 5D instead of the 40D (most likely).

I'm thinking that the IS in my 300mm is worn and is at a threshold that the vibration of the 40D causes it to temporarily malfunction. The different vibration characteristics of the 5D, 30D, and 10D perhaps does not cross this threshold. I'm estimating that my 300mm has shot more than 60,000 images now and a LOT of time has been logged by the IS - more so than by the average non-N&W shooter.

[Canon_Bob]

It could be that the IS needs adjustment. Might be worth sending in for a check. IS creep is fairly normal, but not in the manner you describe. I definitely do not have any of that behavior on mine. I don't, however, use the 300 that much on my 40D. My 40D usually has either the 70-200 f/2.8. or the 100-400 f/4.5-5.6 on it.

[paulnj]

very nice bob!