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Re: Illuminated Crosshairs

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Posted by Glen Warchol/">Glen Warchol on September 22, 1998 22:46:25 UTC

Got it! Yes, I've already installed a "prototype" set of monofilament cross hairs, which are in focus along with the objective's image. Because this is a home-brewed finder with an eyepiece out of a pair of wide-angle binos mounted in a film cannister, I've got room to fiddle with the LED. I might, however, have to run the wiring down the inside of the film cannister to avoid problems with the focusser when it reaches infinity. BTW, the e.p. apparently never had a field stop, per se. It was wide open, but the end of the aluminum mount was about a mm short of the focal point.

: Aperture is how big the field stop hole is. It is usually located : at the focal point of the EP. This is where you are going to put the : crosshairs if you plan on seeing them in focus! This also means that : you will have to make the appropiate fittings so that you will be able : to focus on the crosshairs and then focus all of that on the image from : the objective. If all of that is buried in the focuser because the : field stop is down in there then you are getting into a lot of different : problems. Since the field stop is the largest thing that you will be : able to see in the EP then anything outside of that ring will basically : be invisible (providing that you "black out" any light from the LED. : Clamping is better the word that I used to describe the locating of the : filamants and if you use a lexan or other clear plastic, then you will be : able to route the light to all 4 of the ends of the filaments. Think of : what you need to do and it all becomes obvious to the person that has : done it many times. Most EP's don't get this treatment because they : need to be fixed in the focuser in order to be able to do all of the : things that need to be done - the field stop is down the tube a ways. : Good Luck!

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