Are these two lenses exactly the same, aside from the IS? I own the 70-300 right now and am less than stoked with the sharpness of the lens...especially close focusing. I really believe that maybe I got a bad copy, but that's beside the point. I noticed recently that I can get the 70-200f4 for the same price as the 70-300IS. I would thnk that this would be a good upgrade in glass, but I'm wondering how much i'll miss the IS. I usually shoot in pretty good light, but I do like the IS as it allows me to keep my ISO low in lower light. I looked at the IS version of this lens, but jeez, its double the price. The IS really costs $500, or am I missing something here?

physically they look identical except for a couple more buttons on the IS. i think the IS has a bit more plastic and is 50-60 gms heavier.ohh, the IS is sharper too...especially wide open.but the non-IS is excellent too.ed rader

A top recent copy of the non-IS is indesinguishable wide open at all focal lengths** shot RAW and pixel peeped on a 5D to the edges as an equally good IS example - both are totally razor sharp ..I used numberous older copies of the non-IS and they were excellent but the 80-200L always beat them all at F4 but a very new, non-IS copy I had beat the drainpipe and matched THREE brand new IS models including the IS I currently own...SO if its between a new IS or non IS the Stabilizer is the only difference - and that Stabilizer is worth every penny IMOTested at 50 feet away and infinity -- The IS seems to be a bit better for 200mm closest focussing distance but both are at their worst here, these are NOT macro lenses ..

The IS lens is a newer design. Ithinkthe optics have been redesigned partly to take account of the extra IS element and also due to Canon taking the opportunity to tweak things a bit.However, the IS lens has the integral dust seals within the body of the lens - for me that was an important thing as I like taking pics at the beach etc and at that price I want the lens to be pretty much sealed.Rich

However, the IS lens has the integral dust seals within the body of the lens -Yep - I shoot mine in the rain on the 1D2 - i'd not dream of doing that with a non-IS

surfingringowrote:I looked at the IS version of this lens, but jeez, its double the price. The IS really costs $500, or am I missing something here?Just posted my test on this lens. See for yourself to decide.http://www.flickr.com/photos/hojong/sets/72157601987981541/C & C welcome.Hojong Lin

First off, you will not be happy with either lens at close focus. While razer sharp beyond 10 feet, they are a bit soft at closest focus. If you can afford to stop down 1 or two stops, sharpness increases.The IS version has a newer version of Canon's IS that is said to provide an amazing 4 stops of hand holdability. It also has better dust sealing. It is twice the price of the non IS.I keep hearing people say the IS version is sharper than the non IS version. This is true for earlier versions of the non IS lens. The current version is equal in sharpness.Canon seems to have been doing silent tweaks to some lenses over the last two or three years. The smaller APS sensors packed with pixels require much from a lens and some L lenses were not meeting the mark. Early versions of the 100-400 often had complaints about the sharpness at 400mm. Now the lens is remarkable at 400mm.

.....as its IQ is not good at close to minimum focussing distance at 200mm focal length (my copy and some others report the same).surfingringowrote:Are these two lenses exactly the same, aside from the IS? I own the 70-300 right now and am less than stoked with the sharpness of the lens...especially close focusing.

The 70-200 f4 IS has four additional elements in the light path so they are definitely not the same lens.If your question is if IS is worth the extra money then (IMHO) the answer is yes, but the non-IS is a great lens and much less expensive. I went from the f/4 to the f/2.8 IS and I think my f/4 non-IS was slightly sharper, but the extra stop and IS is getting me shots that I couldn't have gotten otherwise (but its heavy).