I've follwed this thread with interest - I really love my 70-200 f/4 and got to have a play on a demo IS version recently. It was great.
But the increased cost is puzzling. At Warehouse Express, our leading on-line retailer, the 70-200 f/4 costs £478 - you can do a bit better by shopping around, but reputation counts.
They have a pre-order price on the IS version of £990 - that is more than twice as much.
Sure, I'm in rip-off Britain where everything costs in large amounts. But even so.....
The 70-200 f/2.8 IS costs £1249 - again, shopping around a bit can drop this a little.
I think the pricing on this is wrong - if I had to spend that much on the f/4 version, my feeling would be to save up a bit more and get the top-of t-the -line f/2.8 version, and push weights a bit or something!
As it is, I am very happy with my non-IS version, and consider my needs in this range fulfilled.
There are other L lenses out there that come higher on my list!
) - I had the non IS version but just never used it - although I just might be persuaded in 3 months or more to go for the 50f1.2 if it has performance advatages over and above the fast f-stop
.. what it means..?

