In article <4ivo6g$ilt@nntpb.cb.att.com>, rma@clockwise.mh.att.com says...

>In article <8BD244F.0008000DC0.uuout@fotobank.nl>,
>W.J.MARKERINK wrote:
>>FWIW: there is also a Russky 300/2.8 manual around....for half the >>price of the Tamron! At f5.6, it is claimed to be very close to the >>Nikon....;-)

>Of course if you are going to have to stop down to f5.6, then you might
>as well buy the 300/4 and save yourself a bunch of weight and money!
>A 300/2.8 is only worth the expense it it performs well wide open
>and with both 1.4x and 2x TCs. With AF lenses this means you must get
>quick and accurate AF with the TCs also. It is in these areas that
>the 3rd party TCs often look bad when compared to the camera makers
>lenses. On their own and stopped down a bit, most of the 300/2.8 lenses
>are probably pretty decent. Shot wide open with a 2x you may see
>considerable differences!

I second that! And a recent Shutterbug article on Russian lenses
was accompanied by a couple of reproductions of photos taken with
the Russian 300mm f2.8 - the 300mm by itself did not appear very
sharp in the small reproduction, and the lens on a 2X appeared
quite poor, even in the very small reproduction (but, then,
WJM above did accompany his comment with a ";-)"....;-).
Hope This Helps