Post by Chicago Astronomer - Astro Joe on May 17, 2005 23:30:47 GMT -6
Building a new Finder Scope
Always a collector, I have a wide collection of odds and ends of telescopes, lenses and other doo dads that I can't part with...because someday, somewhere...it will all come in handy.
The original finder scope that came with my scope was useless, better off without it and Galileo's scope was superior! I made up a finder scope to replace it with old binocular parts and pvc pipe. It worked well, but aligning it was a pain.
Then...in a moment of motivation I wanted something more. I grabbed my parts case, and spread out it's contents...aperture lenses, diagonals, focusers, brackets and a hodgepodge of other bits. I started out with a rack and pinion focuser from a 60mm refractor. It had good action and feel, this is where I'll start to build my new finder scope. I reused my 50mm binocular objective lens and 90 degree diagonal with 10x eyepiece, but the rest of the pvc pipe I decommissioned.
I coupled the 50mm lens to a slide projector lens holder that I cut down. I didn't know how much to cut down, so I tried cutting in small increments, and testing the focal length view by holding all the pieces in my hand and trying to focus. The technique worked, but it was difficult. The slide projector lens holder, now fit perfectly around my focuser. After drilling holes for attachment screws...I was well on my way to a nice finder scope.
So now, I had the objective lens, ring coupler, focuser, diagonal and eyepiece all assembled, but now...how to mount it to the scope with the ability to align it to the main tube?
I tried many variations of attaching it, with brackets, using the old finder scope rings, copper tubing, plastic tubing...the process of elimination was frustrating, and I thought I came to a roadblock. Then, after a long while, I came across this piece that I have come across quite often over the years and dismissed while searching for other whatnots in my other inventive endeavours. It's the piece that sits on top of a microphone stand that the microphone itself slides into. In a moment of sheer clarity....Eureka!!!!, this is it!...
This solitary piece moves in both alt-azimuth directions and would make alignment a breeze...no more setting screws to fumble with! Perfect! I attached the assembled finder to a wooden dowel, which slips into the holder firmly. I then screwed them both together, but now...how to attach it to the main tube.
I had thought to bolt it on, but that meant I would have to drill out a very large hole in my tube, something I did not desire. But, as luck would have it, the very place I want the finder to be was my old location of the crappy original finder...and the factory holes. I then screwed on threaded dowel into the base of the holder, drilled a pilot hole and fed a good sized wood screw from the inside of the tube to the outside and into the base. A firm fit, and with a split washer...locked in place, but just enough give to adjust. I needed to remove the spider vane to get my hand in the tube, but that was a minor inconvenience.
And this is the result of my efforts.....
It feels good, looks sharp sitting on top, performs well, it's balanced and I get a focuser out of it, instead of backing the eyepiece in or out like we all do with finder scopes.
There is a bit of inner tube diffraction of light, but I'll paint it black one day. I also had to move my beloved Rigel Quick Finder, (oh...I love my Rigel
), to it's present location, but the set up all compliments each other. I go from the Rigel, to the finder to the main tube....and dammed if it all is aligned with each other! I just smile... 
I left the old sticker on the 60mm focuser, as a reminder of where it came from. I used it for the first time this evening at the lakefront at our mini star party. Worked well and it was a good effort and addition to my arsenal...and didn't cost me a dime.
;D
