I have purchased a cover sold for covering outdoor chairs from BigW for about 6$. I was wondering what others are using. Its not perfect as you can not tighten the elastic. But I can probably use a velcro strap to fix that. I was concerned weather such a cover could Zap (static) my scope electronics. It looks like a tarp like material.
I also grabbed a Camping mat for a DIY shield 13, its 10mm thick and I think I could make one with enough left over for another or for smaller finder and guide scopes. I found velcro is quiet expensive, so I have grabbed some waterproof cloth tape from Bunnings for 4$. I wanted to keep to at 3/4 the price of a commercial solution. The best I found was Orion Shield from Bintel for 50$.
What are others using out there. Any precautions or tips?
I have made them out of manilla folders (they last a lot longer than you would think if you lay them flat and dry them after observing), thin camping mats (don't know how you are supposed to sleep on them but they are light and make good shields) and a thin laminate like plastic I found in a hardware once (not sure what it is called, doh...).
I keep a cardboard one in my kit all the time so its there whenever I want it. Attach them with velcro and you are away.
Rob, I had a relisation today that my camping mat shield using tap is not hold a circular shape very well. What I thought was a collimation issue yesterday was infact vigneting from an out of shape shield. Firs thing tomorrow I am going to reduce the size a bit. Its 600mm total but only about 450 hangs out from the corrector. This is more than I need as it should in theory only be about 300-400 for my scope. I will cut of a bit and see if it helps. But the main issue is the tape has a crease where the two ends meet and this cause it to bend inward. The collimation ring pattern looks like it sqaushed a little on one side, but the centre rings are fine and the black spot is dead center. How do people brace there shields? And avoid inward bends?
Your the second person to suggest a Manila folder version to me. thats a very neat solution, how well does it hold its circular shape. Maybe I can brace mine with some flat black thick cardboard inside.
Fahim,
I made a dew shield for my 12"LB out H.I.P.S. High Impact Polystyrene Sheet.
The sheet is 1.73m x 76cm x 0.75mm. Cost is about $20.
It is very strong, flexible and light.
I attached mine with velcro and it does not come off, unless I want it to.
Check out the images.
If you want to waterproof cardboard..you can buy a can of Warpoo waterproofer from shoe repairers shops...just give the cardboard a good soaking spray and allow to dry overnight..it works well on some star charts and maps (check to make sure the ink doesn't run first!) for those dewy nights too!
Cheers!
I went to Clark Rubber and bought a square of foam that was about 5-7 mm in thickness. You just have to cut it to size and hot glued it with a 75mm wide strip that runs on the outside of the join for its whole length to provide sufficient strength - works a charm!
Fahim you only need a dew shield to be about 1.5x your mirror diameter in front of your focuser to work well (in my case that is 300mm so it only sticks out 200mm in front of the tube). With it set up to wrap around the tube end it has a greater diameter than the actual tube it does not vignette the image at all (the tube diameter is 232mm and the inside of the shield is 240mm).
Don't go overboard with the length of the tube and you should be OK.
