super telephotos 8x ++ at DVinfo.net

John Jay · April 8th, 2005, 01:36 PM

For all those in 37mm country heres an interesting review of super telephotos

http://www.cs.mtu.edu/~shene/DigiCam/User-Guide/Odd-Stuff/14x-8x-8x-6x/14x-8x-8x-6x.html

Sean McHenry · April 28th, 2005, 09:54 AM

This is interesting but, there is no way the russian model talked about is a reflector. It is a refractor. There is a huge difference. There is no room in the cylindrical barrel of the model shown for a mirror of sufficient size to keep the light at anything near usable.

If you look at reflecting scopes or telescopes, there is an offset to the barrel where the mirror is housed or, the eyepiece is set into the side of the barrel.

In order to "fold the light path" and make the focal length longer there has to be 2 mirrors or a mirror and a prism. The prism would have to be very good to avoid chromatic (color) aborations (smearing). Hence the price tag would be more.

While the shootout is interesting, I like the 14x myself for sharpness (suprisingly) I still have great doubts there is a reflector among the bunch.

You can see a simple diagram on how various scopes work here:
http://www.omni-optical.com/telescope/ut105.htm

Note the light path on the reflector.

Sean McHenry

April 8th, 2005, 01:36 PM	#1
John Jay Major Player Join Date: Sep 2002 Location: US & THEM Posts: 827	super telephotos 8x ++ For all those in 37mm country heres an interesting review of super telephotos http://www.cs.mtu.edu/~shene/DigiCam/User-Guide/Odd-Stuff/14x-8x-8x-6x/14x-8x-8x-6x.html __________________ John Jay Beware *PLUGGER-BYTES*

April 28th, 2005, 09:54 AM	#2
Sean McHenry Trustee Join Date: Mar 2004 Location: Hilliard, Ohio Posts: 1,193	This is interesting but, there is no way the russian model talked about is a reflector. It is a refractor. There is a huge difference. There is no room in the cylindrical barrel of the model shown for a mirror of sufficient size to keep the light at anything near usable. If you look at reflecting scopes or telescopes, there is an offset to the barrel where the mirror is housed or, the eyepiece is set into the side of the barrel. In order to "fold the light path" and make the focal length longer there has to be 2 mirrors or a mirror and a prism. The prism would have to be very good to avoid chromatic (color) aborations (smearing). Hence the price tag would be more. While the shootout is interesting, I like the 14x myself for sharpness (suprisingly) I still have great doubts there is a reflector among the bunch. You can see a simple diagram on how various scopes work here: http://www.omni-optical.com/telescope/ut105.htm Note the light path on the reflector. Sean McHenry __________________ ‘I don’t know what I’m doing, and I’m shooting on D.V.’ - my hero - David Lynch http://www.DeepBlueEdit.com