Archive for February 2009
This is a post about making a simple collimator for your newtonian/dobsonian telescope. I will not go through the process of telescope collimation which can be found in an excellent article, here. Its easy and it costs nothing. It might not be as cool as a laser collimator but it needs no battery and after some time and with experience you may be able to collimate your telescope perfectly. It’s a method that it already has been described in some forums and books but it harms none to be repeated.
All you need is a film can (tube length is not an issue) and a small knife or scissors. Open a small hole (3-4mm) to the center of cap’s can. It usually is marked already so you’ll not have to make any geometrical calculations for that. You also need to cut the bottom part of the cap. So why a film can? Because it has the diameter of an eyepiece (1 1/4in-3cm) so it fits nice on your focuser.
(Optional) If you want, theres an option to make your handmade collimator, cross haired. You ll be able to “target” the center of your mirror that way and you ll minimize the effort of collimation. Thats easy too! You just have to calculate the points of the circle where you ll place the threads. I have made a small drawing to show you the way. All you need to do is to draw circles of the same radius, centered in the perimeter of your main circle(film can). See the 4 x’s ? All you need to do, is to find the middle point of the distance between them(in pairs). There’s another way, like drawing more circles around until you have something like a starry cross in your circle(that’s easy too-if you want it just drop me a comment) but i was in a hurry and i made it as in the photo (took me some seconds to draw that). When you have found the magic spots just make 4 small cuts and place in them, 2 small pieces of thread.
Thats all! Just saved yourself 20-50 USD or euro. Soon, i ll upload full plans of a Cheshire collimation tool.
Today in the morning i went shopping down town. Being there i located an astronomy shop that i used to visit its website more of out of habit and to see how astronomy equipment is faring here.. I always thought that they try to keep up with all astronomy shops world wide and that they try to expand the astronomy idea to all ppl. Of course not. Most of its working stuff are very experienced sellers that were forced to study telescope mechanics (some), following the “aggressive selling” philosophy (which i hate), plus its prices are ridiculous. Being there, the salesman told me of a mechanism that kept the tripod sturdy and with no vibrations. Well, i asked for the price, and when i was told, i fled running and laughing. He was trying to sell me plastic tripod leg enhancements for 60 euro..(77 USD). To tell the truth i don’t know if that’s a cheap or expensive component, or if it does reduce THAT much, vibrations, but i would never buy something like that at a price i would normally buy a relatively cheap eyepiece.
What i do to my tripod?(I am a dobsonian lover but i still use my old trustful newtonian). Its plain physics and its lots of fun.
I took a half filled (with water..you can use it to water your plants later 😉 ) plastic bottle and made a small hole in the center of the cap. Then pass a piece of rope from the center of the cap and tie it under your tripod base holder and in between the tripod legs. Water will absorb vibrations through the rope and you will have a much stabler experience even in mild wind conditions. More $$ saved ^_^ .. must find that clave eyepieces now…
After some years with fluxbox (with tons of eye candy) and the last 2 years using a combo of ratpoison and dwm, I finally ended up with stumpwm. Stumpwm is the Lisp(y) brother of ratpoison and its actively maintained by Shawn Betts. Ratpoison still kicks buttocks but stumpwm has more features and since its based on lisp, is more configurable[and since im learning lisp it’s good exercise!!]. Most ppl use laptops in observations and i think its a good idea to use a tiling window manager like ratpoison or stumpwm. All my astronomy programs run smoothly and in fullscreen (which is very good for my eyes), plus i have keybinds for calculations that show results in the stumpwm engine.. which is very practical. Of course any kind of coding becomes better and the reason is the absence of obstructive applets, eye-candy panels and such. You have the space to focus on your work which might be a maximized window or a custom layout that suits your need.
In its default state is very spartan and it might require a day or two to fully bring it to your liking. Also according to this post there’s floating support added in the git version. It works pretty well with no resizing yet, but that’s not a problem.. You can check my .stumpwmrc in the ‘Downloads’ page and a screencast which shows a portion of stumpwm’s features, made by male in here. Below, a screenshot with stumpwm running on slack 12.2
UPDATE: Just changed modeline readbility.. seems sexier now..