[Leica] Canon 800mm IS

[rmcclure2 at woh.rr.com (rob mcclure)]

Len,

I believe you are correct about turning off IS when on a tripod.  Even  
my lowly 28-135IS came with instructions to do so for the reasons you  
mentioned.

Rob
On Dec 26, 2008, at 6:01 PM, Leonard Taupier wrote:

> The problem may be because it is an IS lens. I assume the lens, at  
> 10 lbs, most likely is on a tripod. If so there are minute  
> vibrations between the lens and the tripod which cause the IS to try  
> and correct. This correction can also cause the autofocus to  
> continuosly focus, or bounce, causing the photo to be slightly out  
> of focus. It is shutter speed dependent of course. The best way to  
> get a sharp photo with this long of a lens is to have both IS and  
> autofocus off when mounted on a tripod.  The grizzly photo was taken  
> at 1/250 sec which is slow enough to account for this kind of  
> problem. The moose photo was taken at 1/800 sec which should be fast  
> enough to overcome the problem so the photo appears sharp in the  
> back focus area. I have spent a long time on this issue trying to  
> figure out why some of my photos were not as sharp as they should be  
> and not nearly as good as my handheld shots. It is no coincidence  
> that the sharpest photos with long lenses belong to the photographer  
> that shots with manual focus equipment. Also some of the sharpest  
> long autofocus lens shots used sand bags and not a tripod. Of course  
> these are only my opinions based on my own experiences and  
> observations.
>
> Len
>