The Astronomy Connection
Astronomy Equipment => Equipment Discussions => Topic started by: John Pierce on January 20, 2017, 08:08:18 PM
so thinking of the upcoming eclipse, I'm planning on making a safe solar filter for the club's 100mm binocular, which has 25x and 40x eyepieces....
It will need a sun finder, I'm thinking a brass tube, maybe 1/2" diameter and 4-6" long, with a translucent disc 1-2" in diameter superglued to the back... center the shadow of the tube on the disc as seen from behind, perfect. this disc/screen probably should have a nice sharp black dot right in the middle
Whatcha guys think?
I can use this mount I made for a laser pointer...
the binos look like this, they are 45 degree, and take standard 1.25" eyepieces as long as they aren't too fat. The 40X eyepieces are 14mm ES 82 deg. wide, similar to a Nagler, so the actual field of view is 2 degrees.
I'm thinking of finding some suitable cardboard, and taking a strip thats 6" x the outside circumference of the binoculars body, and using that as a template to cut a end piece, with 2 4" holes and thousand oaks solar film, assembled with gaffers tape :) this should slip on and off the binos, if its too loose, I could always use wide blue painters tape to secure it.
ah, my idea of a tube on a tranlucent disk has been done.
You actually don't need one at all, since you can use the shadow of the telescope itself. Just minimize the area
it covers. That's almost always good enough to get the Sun into a low-power view, and you can adjust from
Coronado also makes (for a somewhat outrageous $100) a solar finder for solar scopes. It is essentially
what you have designed, a tube with a translucent screen at one end.
A small and compact design for wide field scopes (or 100mm binos) is a couple of parallel plates 2" apart with a hole in the one towards the sun and a back plate with foggy plastic.
Your holder with the screws is nice to center things so seems ok as you mention. Easy to test before eclipse anyway you do it.
the tube is fine as well if you have all the stuff to make it I guess.
Here is the TeleVue design that is the two parallel plates