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…
One of the most useful amateur astronomer’s tools, is the planisphere. In addition with star maps of objects that you might be interested in, you are able to identify a large part of the night sky. There are many ready made printable planispheres and star charts to get and print. The most known and used is in National Research Counsil of Canada, and one custom made by Toshimi Taki that can be found here. Another one that can be used to know how planispheres might be constructed can be found here. Another interesting way to view a planisphere customized for your country is via GoogleEarth.
So why should you make one by yourself and even sweat about it? Well the magic word (at least for me) is customization. Being able to make custom planispheres or star charts may help you easily focus in the subject you study/observe, change the colors to optimize visibility, change lines,borders or even constellation art. Another reason is the self confidence you might feel, when you construct something that everybody has convinced you, you must BUY to be able to use. The custom planisphere that can be found in the Downloads page is an example. Its still an early version but i ll modify it as best i can. Its written in pp3 (a software that is used to create custom charts) and after a small comparison with a commercial (at least schematically) seems to be working (have to exhaustingly test that one). It lacks labels, days, months and divergence but they will be added in time. In the files section you can find the tex code that is provided by the pp3 script, which is also included.
Now to construct one. The guidelines of Mr. Toshimi Taki are simply brilliant but instead of wood i’d use plastic flexible sheets like the commercial ones. I want it to be waterproof and flexible without the danger of carelessly tearing it apart. Also i want it to be ultra portable. That means that i want to be able to roll it in a cylinder, put it in my pocket/camelback/backpack and be able to use it wherever i am, even in my running sessions. To be able to print it on a plastic sheet i would possibly go to a print shop and choose everything, from material to thickness but i guess its more practical and cheaper to use plastic sheets in your inkjet or laser printer. If you have the printer, the cost of plastic sheets in Amazon is 3.99 USD or you can visit you local bookstore. That way you can have many charts and planispheres or even a clone of the relatively expensive Uranometria with only four dollars.
I ll also try to upload some custom star charts. More updates to come…
Yesterday i found an old pair of binoculars in the closet. The manufacturer is Soligor, based in Germany. After a small inspection the specs are 10×50 and wide angle field of 7°. Pretty sweet for a pair of binoculars that came from nowhere!
The bad news were that it was badly collimated and that resulted in double images. First steps were buying a photography tripod. I just got the taller and cheaper heavy duty stand i could find. It costs about 40 euro from Media Markt, end height is at 1,85 meters and its really sturdy. Next stop was outside a paint shop where i asked for a shelf holder and a 5mm screw (Full cost 30 cents). Simple as possible and the only prequisite was having enough durability to hold the bino’s weight, so it’ll keep the bumps unnoticeable. The holder can stand about 60 pounds (30 kgs) of cargo. It had the same price with the others and its just a bit more bulky. Next stop home. I connected one edge in the photo tripod (it has an embedded screw for cameras) and the other with the screw in the adapter hole of the binos. Simple enough eh? Just for the sake of cost efficiency i visited an online astronomy supplies store to check that the binocular holder is about at 20 USD…!!
Next step is collimation. Collimation in binoculars is an easy process but requires many trial and error steps. Firstly try to keep the binoculars stable and at a comfortable height so that you can see through them easily. One of the best advices i have ever heard about binoculars is that when looking through them, you must be calm. No tension in the neck, shoulders or face. It will just ruin your focusing. Close your right eye and adjust focus using the main switch. After that close your left eye and open the right correcting the focus via the right ocular switch. Yes, double images or in general foggy images will still be there. Under the plastic cover as shown in the picture below are 2 screws, one for each ocular. As you suspect these are used for lenses collimation. You can try adjusting them by looking through the binos at the same time, but you might end up with a pretty scratched surface. The best way is to adjust and check, adjust, check etc. You can try collimating your binoculars by looking at a faraway mark but i would suggest doing so by looking at something bright.. Its summer.. Jupiter is a nice target. Some patience and voila! This pair of old binoculars still has life! I ever consider taking them with me on holidays.
Finally a small tip.. When you want to clean the lens never breath/spit/hrrrr/hhuuhhuuu on them. Never. It will ruin the coatings and decrease image quality… A piece of cloth used for cleaning glasses is the safest way..