Quote:
Originally Posted by multiweb
Hi Rob, you lost me at : "and that the tube extends 1.5x the mirror diameter in front of the focuser (use a light baffle here) "  |
Quote:
Originally Posted by rmcpb
>snip
We "extend" the OTA 1.5x the mirror diameter in front of the focuser. By extending the tube we stop off axis light from directly entering the focuser and reducing contrast. If you get light in there it bounces around in your eyepiece and you end up with a really washed out image. Why 1.5x the mirror diameter? Its generally accepted that this length will stop the problem, any less could allow some ambient light into the focuser. But more is not necessarially better as it adds weight to the front end of the scope and can get into the light path and reduce the light gathering capabilities of your scope.
Cheers
|
Mixed messages? One is talking SCT and one is talking Newtonian. Eyepiece in mirror cell at bottom of OTA vs. eyepiece at side near top of tube.
Cheers
Dennis