Well now that I've been using mainly digital SLR's, I'm starting to figure out what exactly I need.
I love my old MF lenses that I've gotten - and they take great pics. But of course since they're manual, capturing Aviation photos of planes in flight is a bit difficult. (Was using mainly my Nikon AF 80-300 ED and my bang-up Rebel XT). They do take awesome pics of static Aircraft.
I took my Olympus E-420 out with the 40-150 (80-300 equivalent) and the AF made things much easier.
I only have the kit lenses (18-55 non-IS) with my 20D and Rebel XT (both of which I got used for prices than less the bodies only were going for). I've taken great pics with that lens! But then I was able to borrow the 300L IS - that was awesome! But, it is well out of my price range and I prefer zooms.
I was looking today at the highly-toughted 55-250 IS, but that seems to not have that panning mode IS.
Is IS really that necessary? I heard they don't do any good if the subject is moving.
Can I get away with an older non-IS lens and a higher shutter speed.
If I use higher shutter speeds - then there's that whole "prop freeze" thing...