No answers yet? C'mon guys! This is a great post and a great subject for discussion.

I've got two digital SLRs which I use differently, a Canon EOS 10D and an EOS 1D. I bought the 1D first, for shooting mountain bike racing. It replaced an EOS 3 film camera. The 10D was purchased about a year later, as a backup for the 1D. I use the 1D mostly for racing or anything where timing, speed, and AF accuracy are my top requirements. The 10D goes on shoots where I have to ride, and gets used whenever image quality and resolution are the top priority.

I have a bunch of lenses - 300 f/4L, 70-200 f/2.8L, 20mm f/2.8, 15mm f/2.8 Fisheye, 50mm f/1.4, 50mm f/2.5 Compact Macro, 28-135mm 3.5-5.6 IS, and the Canon 1.4x teleconverter, as well as the Canon Lifesize Converter.

Lately I've been using the 28-135mm IS and 15mm Fisheye the most. I can carry both, with the 10D and a flash, in my hydation pack, on long mountain bike rides. If I need good bike photos, and I need a bike to get there, this is what I take. After I started shooting digital, I abandoned the 28-125 for about a year. But then I tried it with the 10D and found I love it. The optics are great, with the 1.6x digital conversion the reach is incredible, and it's relatively small ad light. Along with the Fisheye, I've got a pretty complete camera kit that's fairly light and compact.

When I'm at a race or other even, I've most likely got the 70-200 f/2.8L mounted on the 1D. For pure speed and precision, it just doesn't get any better. The AF combo of the 70-200 and 1D is so ridiculously fast and accurate, it makes my head spin. It also messes me up when I shoot with the 10D because the 10D is sad in comparison. The 70-200 f/2.8L (or the Nikon 70-200 AF-S) is probably one of the most versatile lenses ever made. It's a landscape lens, a wildlife lens, a sports lens, and a portrait lens. Anyone who's serious about their photography should have one. Or the f/4 version. The 70-200 f/4 L is the only lens my dad owns.

I shoot a lot with the 70-200 f/2.8L and the 1.4x converter, too. On digital SLR with a smaller than full-frame sensor, you have the reach of a 300mm lens, on a zoom, with a fairly fast aperture of f/4.0. It's great when I want more range or need to set up for a longer shot.

The 300mm f/4L doesn't get used as much is it used to. I bought it for motorcycle roadracing, which I don't shoot anymore. A 300mm lens is pretty much the minimum for roadracing. You can't get very close so long lenses are an absolute necessity. The optics on the 300mm f/4L are awesome. But the AF is a little pokey.

I haven't been shooting as much with the wide lenses, lately. I like the 20mm prime a lot, though. If I could only have one lens for the 1D, it would be the 20mm. Optics are good, it's always fun, and the angle-of-view makes a good normal lens on the 1D - for me. The 2.8 aperture makes it a good lens in low-light, too. I'd like something even faster. But after this, the prices go way, way up.

Of the 50mm lenses, I use the f/2.5 Macro the most. That's because I do a lot of product photos for camera reviews and it's a great lens for close-up work. Sometimes I wonder if should sell the 50mm f/1.4. But it's really in a class by itself. I don't use it that much, but I can't part with it either. It makes a wonderful, wonderful portrait lens on the 10D.

That's what I've got. Hoep that is enlightenting in some way. I'll go through your post again in a bit and see if there's anything specific in your list to respond to. But I thought it would be nice to just list what I've got and how I use it. I'll also see if I can get some of the folks hanging out on ViewFinder to join in on this discussion.