hi.

most of my shooting concerns small creatures; birds, lizards, etc and I've recently realised that in most cases, I require f16 or smaller to get enough DoF for my subjects.

that said, is there any advantage to buying the very pricy 400/4.0DO vs the 400/5.6L?

regards,
Gregory

The only thing I can think of would be that the viewfinder would be slightly brighter at f4 than f5.6 and that you're AF should have an easier time of it with the extra light.

I'd buy the cheaper one.

two big advantages for the DO- image stabilization and the ability to autofocus with a 1.4X

i'd bet at f16 you're diffraction limited and i'd bet you won't see a difference in image quality

"two big advantages for the DO- image stabilization and the ability to autofocus with a 1.4X"

whoops. missed the IS difference. and being able to auto-focus with the 1.4x extender is definitely a plus. bummer! now there's no choice but to buy the expensive DO lens.

thanks for the heads-up.

If your leaning towards the 400/f4 DO, you might also want to consider the 500/f4 as they seem to be around the same price (although a chunk heavier).

Marlyn

Yes, I have both but almost always use the 400 DO because it is easily handheld (even with the 1.4X). The 500 mm will wear you out VERY quickly if it is not on a tripod.