Thu 07-Mar-13 12:01 AM | edited Thu 07-Mar-13 12:03 AM by nrothschild
OK, assuming he is doing a little bit of everything, that is the choice I would make too, knowing what little I know about the Canon lenses except they are pretty much like Nikon lenses.... primes usually beat zooms.
What I understand about the Canon choices is that the 400 prime is sharper than the 100-400 (as you would expect). It is a matter of degree and that is not clear to me.
The problem I have, and the problem of all small bird photographers, is that these migrants are rarely out in the open where you can even expect to reliably get a 1/500s exposure.
I would estimate that 80% of my birding images are shot at 1/250s, ISO 400, and between f/5.6 and f/10 or so. Since I use flash whenever possible on my tripod mounted lens, that actually works in my favor because I can set my camera (manual exposure) to iTTL, 1/250s, ISO 400 and f/8 and in an amazing number of situations it just works.
I'm usually shooting my 500/4 and either a TC14 or TC17, so any time I can go down one stop in focal ratio from wide open I do. If most of my shooting was without flash, and I didn't have to worry about flash sync speed ceilings, then rather than dropping to f/10 I would jump the shutter, but I would still be lucky to get 1/500s at f/5.6-f/8, which is the upper end of VR usability.
The only time I exceed the above by more than a fraction of a stop, I must be in fairly direct sunlight, and my exposure can be well over 1/1000s. And in that case I don't need VR and VR won't help anyway. Edit: that is less than 10% of my shooting ops.
If I were out at a refuge impound shooting waders then I would generally only be shooting in direct sunlight, probably around an hour from sunrise or set. Plus, I would be on a tripod, or at least a monopod. That is why I asked those questions.
Because most of my small birding shots are well inside VR shutter speeds, and because it is so difficult to shoot small birds with a hand held lens, I put a lot of value on VR for that use. More than I do for my tripod shooting, where I also do not have VR. In my case I make due with my 300/4 + either TC, but I lose a lot of shots.
In principle I should use a monopod. The problem is that if I carry a monopod it has to be attached to the lens at all times. And then it has to be slung over my shoulder. I find that in that mode it is difficult to walk and look up all the time, and that is what is required for good birding where you are searching out secretive birds.
I hope this explains that in many cases the choice in Canon land between the prime and zoom is a tough one. Up until now we have had this strange choice of VR with a not too sharp at 400mm screw driven lens or a great lens (300/4) without VR. But I know from experience that hand holding that non-VR lens in typical hand held birding situations is not a great solution either.