<p>If you can afford the relatively small max aperture, don't discount the 500mm f8 mirror. It is much more handleable lens.<br>
I have a Canon SSC breechlock version . If you found a FDn mount version you could get it converted to EF mount here <a href="http://www.thelensdoctor.co.uk/index.html">http://www.thelensdoctor.co.uk/index.html</a>.</p>
<p>I also have a Sigma 600mm f8 mirror which isn't a bad lens either. </p>
<p>Before it raises a storm of comment, I am well aware that mirror lenses are what we call in the UK "marmite lenses". (For those of you in the colonies who haven't come across Marmite, it is a yeast based spread for toast or sandwiches. There are no two ways about this stuff, you either love or loathe it!)</p>