« on: August 17, 2011, 03:30:44 PM »
Edwin, I think you've got the wrong end of the stick. My comment on a 200-400 range being a short zoom range remains. Yes, the 200-400 extender would mitigate that by the built in extender, so overall we're about a 3x zoom then.
I never said the zoom ratio was a significant indicator for image quality. It may be a compact camera marketing spec dream, but even in DSLR-land it has some use. As a generalisation, for a given general quality level, if you want faster, you get less zoom range. Primes get the biggest apertures but no zoom. f/2.8 zooms have a short range. f/4 zooms get a bit longer. At f/5.6 you can get pretty much as much as you want. That was my point in looking at the zoom ratio. For a f/4, the 200-400 is a relatively short range. Maybe they wanted to make it extra special? Or it was required to make the extender work better.
On the 100-400L vs the 400mm fast primes, that's not exactly comparing like with like is it? Does a zoom really have much of a chance keeping up with something of fixed focal length and big aperture with price tag to match? If you want much better you have to pay for it. The 100-400L is still very competitive for the focal length range and cost.
My interest in these longer lenses is for wildlife. Sure, many times I wish I had something longer than a 400, but the 100-400L does the job well. The two sticking points for me with the more exotic teles is not the price, but a combination of them being prime and the weight. The weight can't be helped, but the prime doesn't sell it for me. I had a 300/2.8 for a while, but didn't find myself using it as it lacked flexibility. Even the short zoom of the 200-400 extender would help a lot there I think, even if it wont help on the weight side, and I'm not looking forward to finding out how much Canon want for it!
On the "dust pump" I've never had a dust problem with the lens or sensor and I do use the 100-400L a lot. Probably over 80% of my lifetime photos are taken with it. You can tell the front isn't sealed, as the pressure when pumping it does change with a filter fitted compared to without. I found that air vent handy actually as it helps dries out the lens elements faster when I get condensation inside. Stick a cap on the back end and pump away!
Hypothetically, if they remade a future 100-400L in the style of the 70-300L I would be disappointed. The 70-300L just isn't as good to zoom with, although it has its charms like not needing me to dry out its insides like I do on the 100-400L...