View Single Post
  #32  
Old 15-01-2007, 06:44 PM
Dennis
Dazzled by the Cosmos.

Dennis is offline
 
Join Date: May 2005
Location: Brisbane
Posts: 11,828
Hey Matt

I just read an article on the C14 Yahoo group about a guy who wanted to minimise mirror flop on his C11. He took it apart and inserted 3 custom made “spacer” bars around the edge of the mirror. These spacers were placed longitudinally and were curved to fit snugly against the inside of the OTA. Screws then “pushed” these delrin spacers against the mirror to reduce flop.

Here is an interesting excerpt on how easy it is to deform the mirror:

“I centered on a star and slightly defocused the image to get a series of star-test rings. Then as I brought the mirror locks into contact with the mirror I could easily see distortions in the diffraction rings and visible degradation of the focused image. The bottom line is that you cannot apply much force at all. How much is too much? Imagine getting in your car and turning on the radio. The amount of torque you give the volume knob (at least in my car) is about how tight you can make the screws without distortion”.

Cheers

Dennis
Reply With Quote