In article <4dbf11$rqa@newsbf02.news.aol.com>, brucemount@aol.com says...

>>>From: d_ruether@hotmail.com (Bob Neuman) (about a test of Canon IS lens)
>>>Sorry, that is irrelevant, since the exposure was made with flash,
>>>and that was (presumably) the primary light source. <..it was..>
>
>I think your point is partly true, but not completely accurate. If the
>flash canceled the shutter speed, then why was the resolution without >IS <..Image Stabilization..> on twice as bad? (Excepted below...)
>
>> f/8 300 mm. focal length
>> Handheld, no IS 39.2 lpm
>> Handheld, IS 70.0 lpm

I have also pointed out the reason to the original poster (and it was mentioned in my original response to the original post) There are two questions here:

1) Does the IS aid in hand-holding the lens at slow shutter speeds?
2) Does the IS aid in accurate focusing (since doing the test with flash made the hand-holding question irrelevant)?

Since the "shutter speed" of the flash was at least 1/500th second,
the test did not answer the first question. The results from the lens
at 300mm on the tripod, off the tripod with IS, and off the tripod with no IS (except during focusing), would all be about the same at the
1/500th+ flash "shutter speed". The one that would be different would
be the one shot with flash, but with no IS during focusing (and, probably, one shot without IS without flash, and at a slow shutter speed). It is difficult to focus a moving image, especially a flat test target which, if not EXACTLY focused, would give a lower resolution reading. The IS, by steadying the VF image, would aid in achieving more accurate focus on the target. I am not saying IS doesn't work (the test did show IS is useful for better hand-held focus accuracy) - a continuous light test will probably show that slow speed hand-held sharpness is also improved, but THIS test did not show that.
Hope This Helps