[Phoenix (Steve)]

Hi Folks
This may be a no-brainer to most of you, but despite some web search efforts, I have never been that happy with advice on how to attach my Bahtinov mask to my refractor until I read a couple of sites that suggest using sewing rings/hoops. Basically the idea is to attach your focusing mask to a sewing hoop then slide the hoop easily and securely over the end of your scope. The hoops are easily found in craft stores, or stores like Lincraft or Spotlight. So for the uneducated, like me….

Taking note of the outer diameter of my WO Megrez 90 and my 72 mm guide scope, I purchased several hoops that, with some shimmying, would fit snugly over the ends of these scopes. Each hoop has an outer and inner ring – the outer ring was discarded to reduce weight. I then ordered several wonderfully made acrylic Bahtinov masks from Mike (aka ozstockman) http://www.iceinspace.com.au/forum/s...ad.php?t=47090, with outer diameters the same as the outer diameter of the inner hoop rings. I then simply used double sided tape to attach each mask to the wooden rings (you could use PVC glue instead). Finally, I found that some 6 mm self-adhesive Raven weather strip stuck to the inside of one of the rings allowed the Bahtinov mask to fit snug and centered to my 72mm guide scope.

For the 90 mm scope, a larger ring was used, but the ring only just fit over the end of the scope so a little sanding was required to the inner ring. This also allowed me to glue some 10 mm black velvet ribbon to the inside of the ring so the mask would slip on and off of the scope smoothly and easily – not to mention, protect the end of the scope from any scratches. The end result was a perfect fit of the Bahtinov mask to my Megrez 90 scope.

There are many different sewing hoop sizes so I’m sure you could find one to suit most scopes. I found the method above provided an accurate lightweight solution to attaching the masks effortlessly to the scopes.


Like I said.... this may be a common approach, but for those of you like me who were unaware of using sewing hoops for attaching focusing masks, then I hope this helps.


Cheers
Steve