It appears when I use it with the Canon 350D the photos are not sharp while they are fine with the 30D. They are not totally out of focus but they are far from being sharp and it is noticeable without looking at a 100% crop of the photo.
I wonder if it is because of the not so good autofocus on the 350D :confused:
With the 70-200f4 (or any other lenses) the 350D works very well and photos can be extremely sharp like at http://www.photoboard.eu/photography/showphoto.php?photo=2247

Did you try with the camera on a tripod and the same settings?manual and auto focus?
Maybe when you took the photos,the conditions(light,humidity)were not the same,and this is why you see the difference :confused:

No, I haven't tried on a tripod but I never had blurry pictures like that, especially on a not so fast subject (soldiers walking near Buckingham palace).
On the same day I had the 30D with the 70-200 f4 (all pictures fine) and the 350D with the 300 f4 (all pictures blurry).
I am going to try some tests with the 350D and the 300 f4 right now. I just came home after doing some tests of the D200 and the 30D with pictures taken in the same conditions.

On the same day I had the 30D with the 70-200 f4 (all pictures fine) and the 350D with the 300 f4 (all pictures blurry).
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Many times i have taken blurred photos using the Canon D60 and fine photos with the Canon 20D using the same lenses,but both cameras on the tripod take nice photos.

Blurred photos will likely result from handhold shots at the 300mm,that is why i suggest you try with the camera on a tripod.
Did you check the EXIF of the blurred photos?make sure that the shutter speed number is bigger than the focal length.

The weather was too bad (rain) to test again the 300mm.
Tomorrow afternoon it is supposed to be sunny.
I did check the shutter speed and they were from 1/800 to 1/1600 and the image stabiliser was on most of the time so I do not think it was me shaking but I did notice one sharp photo and it was a photo of a decoration on top of a street light.
How do you explain the difference in photos between the D60 and the 20?

The weather was too bad (rain) to test again the 300mm.
Tomorrow afternoon it is supposed to be sunny.


I do not think it was me shaking but I did notice one sharp photo

Why don't you test the camera inside?If you take a sharp photo with the camera on a tripod,you will make sure that it would be not a technical problem (backfocus or something else)

How do you explain the difference in photos between the D60 and the 20?
I suppose that the Canon 20D is much better that the D60 in low light....maybe due to the sensor?i'm not sure why.
Both cameras when on a tripod take sharp and not blurred photos.

I did not try indoor earlier because my studio is small and it looked funny to try a 300mm lens with a minimum focus distance of 1.5 metre in that small space. You have to come back to London to see the average studio size here ;)
Well, I managed to find some space and at close distance there is no problem. At long distance it is often blurry even on tripod. I believe it is the autofocus not able to focus well under some conditions. On the 350D the autofocus points are tiny. The central point is extremely small compared to the central point on the 30D and you can miss a photo just because the point was 1 cm next to the target.
On short distance like 2 metre it is easy to put the AF point on something like someone's nose and the photo will be sharp. At 15 metre when you do not see the nose well and simply focus the center of the head, the photo will be blurry. I had about 230 blurry photos of "Trooping the colour (http://www.royal.gov.uk/output/page4934.asp)" preparations, all taken during a very sunny day. What a pity. Fortunately the photos taken with the 30D were good. Next time I will use the 350D with the 70-200 which works very well on that body and the 30D with the 300 (excellent too).

It's very good that it's not a problem of the camera that needs to be repaired!:)

Yes, lucky in some way but still annoying as that camera can't use that lens. I found another problem between lens and camera I will post on the D200 thread.