"John Sheehy" wrote in message ...
nick c wrote in news:463c0b8b$0$4667
:

I would like to add:

Canons 70-200 f2.8 L IS lens coupled to Canons 2x telextender attached
to a 30D (or 20D) gives excellent results at F5.6 at an equivalent
640mm; keeping the use of Modes 1 and 2 IS. This setup is what I use
for wildlife photos; still retaining the basic 70-200 for conventional
use.

I have never seen a sample from the 70-200 f/2.8 IS with a 2x TC that
looked anywhere as sharp as a good 100-400 @ 400.

TCs are good for getting a little more subject detail out of a given lens;
it is not a substitute for lenses that do the same thing without TCs.

--


John P Sheehy


Oh, but in many ways they are a substitute - that's why they exist.

For those of us that lack the budget to buy a set of lenses with the reach we want for any situation, or to hire a porter to carry
them for us, a TC is a good substitute. Sure they're a compromise but, hey, that's life. If I have to choose between getting a shot
with insufficient detail due to a lack of magnification at, say 500mm, or a shot that's got the extra detail at 700mm but is
slightly softer than I'd get with a lens I don't have that costs 6-8 times as much, or more, and weighs 3-4 times as much, or more,
I know which I'd choose.

Cheers
--
cmyk