How to make a simple finder

The purpose of keeping a finder on top of any telescope is to quickly target the object you want to see through the telescope. Finding the required object only through the main telescope is extremely difficult as it is seeing around ½ to 1 degree view (Sun and Moon are1/2 degree wide). It is like searching a pin in a hay stack hence the need to put a finder gun-sight or finder scope.

The ideal finder scope should be of around 6 to 8 magnification having around 5-7 degree field giving true erect image and with a cross, so as to quickly find the target object to be seen through the main telescope. This type of finder scope involves putting an achromate lens, erector asseembly and eyepiece, so it costs around Rs.350/-. You can fix this Finder scope with its cradle as shown in the Main Page or

 

Tripod Page. A simple finder gun sight made up of two eye bolts (with hole as shown in picture) used in bicycles to tighten the chains is also good enough for searching the objects. Fix one bolt by two washers and nuts near the centre of the telescope tube. Fix another bolt in straight line and at the same height at the other end of the tube near focuser. Make slightly long around 3/4" long cut on the

telescope tube so that this bolt can not only be inserted but also adjusted (right/left) and also up and down in order to place the viewing object in exact centre of both holes. Also see the picture of the assembled telescope in 'Tripod Page', where to fix these.

First you have to see any land object through the telescope and then adjust this 2nd bolt right/left or up and down in the slit, so that, that very object is also exactly in centre of these two bolts. After setting thus, tighten the 2nd bolt at that very spot. Now, whatever astronomical or land object you want to see, you center that desired object in these two bolts and that object will come instantly in the view of telescope i.e. these bolts now will work as Finder Gun Sight.

Next page (Assembling), contents