Hello all, Well after a bit of research and some advice from the Club i decided to buy myself the 70-200mm F/4 L Non-IS (due to mother-in-law taking our Christmas presents back and giving us the cash (plus £100 from me ). The reason i didnt go for the f/2.8 is price and weight. And the reason Non-IS over the IS version is because now i can afford a 1.4x converter and plethera of filters. Anyway the Club suggested that the IS is cancelled out by the ISO handling of the 40D and i thought i would put this to test. I sat on my sofa in dim light (closed all curtains bar 1 behind the subject, and put a lamp on next to it) and took a photo from about 5 metres away. All handheld Here are my results. CLICK PICS FOR LARGER PICTURES OR CLICK HERE FOR A SIDE BY SIDE GRID COMPARISON The little pic is a 100% crop ISO - 100 Exposure - 1/10 Aperture - F/4 Length - 200mm ISO - 200 Shutter - 1/20 Aperture - F/4 Length - 200mm ISO - 400 Shutter - 1/40 Aperture - F/4 Length - 200mm ISO - 800 Shutter - 1/80 Aperture - F/4 Length - 200mm ISO - 1600 Shutter - 1/160 Aperture - F/4 Length - 200mm ISO - 3200 Shutter - 1/320 Aperture - F/4 Length - 200mm I hope it helps someone make a decision on which 70-200mm to buy.