In article . 144,
"Peter.D.Evans" orbscure.AT.hotmail.DOT.com wrote:

Are any of you photographers out there using either the Sigma 50-500
or Tamron AF 200-500 lenses? My plan is to purchase either for use
on a Nikon N80. If you are, I'd appreciate your thoughts with regards
their use for airshow display photography - and some examples of your
work using either posted here would be great too please!

How fast is each?