Make your own TelRad Reticle

Wanna make a scope? Or better still, grind a mirror yourself. Or, you have some good tips in making a really useful accessory? This is the place to show what your hands can do...
Post Reply
User avatar
weixing
Super Moderator
Posts: 4708
Joined: Wed Oct 01, 2003 12:22 am
Favourite scope: Vixen R200SS & Celestron 6" F5 Achro Refractor
Location: (Tampines) Earth of Solar System in Orion Arm of Milky Way Galaxy in Local Group Galaxies Cluster

Make your own TelRad Reticle

Post by weixing »

Hi,
I'm not good at estimation, so always got problems to accurately point at object even when using Telrad or Rigel Quick Finder. Since I got a Telrad, I decided to replace the bullseye reticle to a grid reticle and to my surprise, it's very easy to do it.

The Telrad bullseye reticle can be remove very easily... may be too easy for my copy.
Image

After the bullseye reticle had been remove, you'll see there is a translucent screen behind it. The screen is use to diffuse the red light source behind it and act as a constant circular red light source. Due to the size of this circular red light source, the maximum possible angular projection is limit to around 4 degree. Below are the original bullseye reticle measurements:
Size of reticle: 17mm x 17mm
Outer Circular Reticle (4 degree): 9mm

Base on the measurement, the scale use by the Telrad reticle is 2.25mm (9mm/4 degree) per degree. Using that scale, I made a grid base reticle using my computer and print on transparency.
Image
One issue is the "black" background my printer print is not totally opaque, so I paste 2 of them together using double sided tape to make the black more opaque. It's improve, but still can see some of the light on the background of the projected reticle when at maximum brightness.
Image

I think this shouldn't be an issue (hope so) as I usually won't turn the brightness to maximum, so need to do some field test. Here is an image of the reticle at normal brightness and the photo of the reticle in the Telrad.
Image
Image

Anyway, I paste the reticle on the screen using normal glue and it seem to stick on the screen quite well... If it drop off, I'll use more "powerful" glue. :P

By the way, I also made a star hop grid reticle template for Pocket Sky Atlas.
Image

Hope this new reticle can help me point at object easily without using my optical finder.

Have a nice day.
Yang Weixing
:mrgreen: "The universe is composed mainly of hydrogen and ignorance." :mrgreen:
User avatar
Tachyon
Posts: 2038
Joined: Wed Jun 01, 2005 11:40 am
Location: Bedok

Post by Tachyon »

Nice! I may try it on yours before I decide to modify mine... :)
[80% Steve, 20% Alfred] ------- Probability of Clear Skies = (Age of newest equipment in days) / [(Number of observers) * (Total Aperture of all telescopes present in mm)]
User avatar
Canopus Lim
Posts: 1144
Joined: Fri Jun 03, 2005 12:46 pm
Location: Macpherson

Post by Canopus Lim »

Nice idea. The reticle should be as 'thin' (as few transparency) as possible. If one stack too many (the thickness increases), then the projected reticle will be less sharp. Or maybe you could try using an opaque very black construction paper and use a very sharp knife to cut the lines of the grid?
AstroDuck
Post Reply