Hi--

>>It is a wonderful lens for hand-holding
^^^^^^^^^^^^^^ Really? It is rather difficult to
hand-hold at 200mm at dim light.

>Each time I try to mount the big lens on my F90 on tripod, I will be afriad
>if the lens mount can support the weight of the lens. Besides, with this
>setup mount on my heavy Manfoto 190 tripod, there still is a level of "shake"
>on the result slide.

I can do pretty well with this lens at 1/60th at f2.8 at 200mm hand-held, something I can't do with lighter/slower lenses.
The mount is OK, if no major force or disturbance occurs (I would not carry
the tripod with the lens-camera on it). The Manfrotto/Bogen tripods are very
sturdy, but not very steady - they can support a lot of weight, but they are
not well damped. Try holding the lens near the end while contacting the tripod
with the side of your arm at 1/8 through 1/60 - you may find that your damping
gets you sharper images on a tripod at these speeds.

>The price of the collar from Kirk is too high for me, and I have considered
>to install a mount which is made from other manufacturers about their lens at
>similar focal length. For instant, the Canon EF80-200 2.8L, Sigma 70-210 2.8
>etc.
>Is it possible? Any other alternatives?

I think you are giving up too easily - the 80-200 works! The Canon lens is not adaptable, though the Sigma comes in Nikon mounts, but if you know what the
Nikkor does, you may be disappointed.... If you have access to an Arca B1 and
a Really Right Stuff plate for the N90, that works well, though it is not so rigid as the Kirk (but it is more convenient.
David Ruether

>Best regards,
>Chan Chai-hoi
>³¯ÀÙ³ĺ
>e-mail: mandiu@ecs.school.net.hk