70-300MM DO IS Vs. 70-300mm IS

Hi - Does anyone have any knowledge of whether the DO version of this lens really justifies almost twice the cost please?

Thanks

If you value L-quality build, FTM focus and a non-rotating front element in a very compact package then definately yes. Image quality wise I have not compared the two but the new 70-300 IS does look good so probably not much in it in the real world - the new 70-300 is very plastic though.

I owned the DO. still regret selling it and wouldn't hesitate to buy it again if I could justify having it as well as the 100-400.

PS. Just noticed this was your first post Ian so welcome to the forum!

The DO has excellent build, real/ring USM (not fake USM like the 70300IS), FTM, and generally good optics. However, when using both I couldn't find it in me to choose the DO over the new IS lens. It costs 2x as much and doesn't have any optical advantages (many would argue that the new IS has better IQ even, something I would agree with). I don't want to put down the DO so much but would rather say, "Check out the new 70300IS" -- it's that good. See my test here http://www.pbase.com/f​stopjojo/70300s

Guys - many thanks for the info. Nitsch - thanks for the welcome.
I'm still torn, so many lesnes I want, so little money! Not to mention the 580EX I (think) I need!

If there is one thing that really frustrates me it is softness in photos and I guess that this will always be an issue with zoom over prime. I'll see if I can try one at my local camera shop @300mm and check the results.

Thanks again...