fast telephoto lens

Hi,

Telescopes as Swarovski-Habicht and Kowa do have a telescope adapter but it
is at F8 or F11 : an 800mm adapter at f8 and a 1100mm adapter at f11.

Cheers,

Luc


".::SuperBLUE::." <SuperBLUE.RemoveThis@dontusaefakevip.hr> schreef in bericht
news:cutof8$i8c$1@ls219.htnet.hr...
 > Is it possible to make a system similar to the 400mm f/2.8 for dslr
 > cameras
 > out of a telescope
 > and a adapter? Which telescope? 150mm/ 6inch one? Which adapter?
 >
 ><!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: fast telephoto lens 

..::SuperBLUE::. wrote:
 > Is it possible to make a system similar to the 400mm f/2.8 for dslr cameras
 > out of a telescope
 > and a adapter? Which telescope? 150mm/ 6inch one? Which adapter?
 >
 >
You will have a hard time getting f/2.8 from a telescope.
Telescopes with that fast of an aperture are special designs
that often have curved film planes, like Schmidt telescopes,
or would be quite expensive.

But you could get f/4.5 to f/6 effectively. I've tested
a 6-inch aperture f/6 homemade Newtonian, and it
delivers very sharp images, in fact sharper than
top end telephotos. That equates to a 914mm f/6 telephoto,
that cost only a few hundred $ to build.
The problem is focusing. If you intend to do astrophotos,
there are focusing aids (do a google search for DSLR focus),
but if you want to do wildlife photography,
where focus is constantly changing, it would not be
a good solution. Focus is very difficult with
DSLRs unless you can change the focusing screen and
can install a better microprism.

I settled for a 500 mm f/4 L IS telephoto.

Roger
Photos at: <a style='text-decoration: underline;' href="http://www.clarkvision.com" target="_blank">http://www.clarkvision.com</a><!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: fast telephoto lens