Canon's 800mm IS on a tripod - IS moves a lot!
Greetings All,
I just posted this same question on the Canon Digital Photography forum and most of the responses related to general IS and switching it off while lenses were on a tripod (not applicable to the newer IS generations, correct?). I figured some birders here might own an 800mm...
I gather the IS on the 800mm states - "IS system is tripod-sensing - it shifts into a secondary stabilization mode when mounted on a tripod - it specifically helps correct mirror slap"
I just had my Canon 800mm (purchased in 2010) serviced by Canon and I was double checking the autofocus with the LensAlign MrkII. I noticed while in live view at 10x magnification just how much movement was happening with the IS on - please see this video - http://youtu.be/_T8REC007iE - the video starts with IS off and then on and off a few times.
For the video - 800mm was on a gitzo carbon fiber tripod with a Mongoose 3.6 gimbal tripod head and inside the house, so no wind (and I wasn't dancing...)
I then did a few comparisons of images at low shutter speeds (1/30) and found the images with IS on were fuzzier than those with IS off. I had the lens sitting on the floor with two solid contact points touching the floor - tripod plate and camera battery-grip. Also, I used a remote shutter release.
I guess my real question is for those of you with experience with the 800mm - is this much movement normal? and should there be a loss of sharpness with IS on at shutter speeds of 1/30? I recall reading in A. Morris's Bulletins about using his 800mm at 1/30 and how pleased he was with the results (I assumed the IS was on?). I'd say it was my poor technique that produced the lower quality images with IS on, but I took 5 comparisons and all yielded the images with IS off images to be the sharpest.
Thanks all for your time and in advance for any feedback.
-Ronan