lens opinions

[Warthog]

My thoughts are "what is the focal length that you are likely to use most?" If you are shooting over 200 then perhaps the Nikkor is best. However, my feeling would be go for the Sigma...

Having said that, IIRR, the issue with teleconverters is that you loose autofocus and 1 or 2 f stops. However, I seem to recall that autofocus was not affected if the lense is fast: perhaps f2.8 would cope...

I mean its great having a 400. I have a 200-400 for my Dynax 7D but, realistically, its not a focal length I use that often unless its for wildlife.

Personally, I think that the f2.8 is more attractive. It really opens up what you lense and camera can achieve. My 400 is a 5.6 and it can make certain shots less likely.

You have narrowed down your choice, but out of interest, why did you reject the Sigma 28-200 lens: they have a very good rep....