DIY Barlowed collimator

I've got a stock laser collimator with my Dob. Its construction is based on some primitive China made keychain laser pointer enclosed in the aluminum tube with a side window. It's really frustrating to work with, so I've been looking for alternatives for a while.

After searching online I've realized that this construction is quite common in cheap accessories from many vendors, the Orion for example.

Telrad

Not so long ago I've got acquainted with the Telrad object finder. This is definitely the king of all zero magnification finders, and I believe of many optical finders as well. Just remember that it is not just a red dot finder, which you are most likely familiar with from experience with some cheap telescopes. You need to learn how to use it properly in order to achieve unbelievable accuracy and pointing time under 10 seconds for any kind of celestial objects.

If you have a large enough aperture telescope (I believe it must be more than 8") you should consider getting and installing the Telrad device, which is around $40 at any popular astronomy store. Telrad may not be practical on small refractors as it's quite large. Despite that, it's relatively lightweight, even though it's using two AA batteries. The size is dictated by the need for a long enough light path for the collimated reticle image building. There are many DIY Telrad mods instructions and accessories for purchase available online. Most notably:

• Dew shield
• Dew Heater
• Riser base
• Blinker (Pulser)

However, it works for me as is so far.

Ball handle

The first modification I've made to my stock Zhumell dob construction was the ball shaped handle underneath the OTA for more comfortable scope pointing and star tracking. The pink high density closed foam bounce ball, which I found in my son's old toys bin, fitted that role just perfectly. Its size feels good in the palm of a hand, and the soft foam material provides especially good feeling in cold temperatures compared to the ice-cold metal of the OTA or other solid handles I used in the past.

After experimenting with different postures behind the eyepiece, I used a convenient location for a brass bolt (3/16") with the wide head and some steel washers for the spacer to install the ball in the convenient place suitable for work behind the eyepiece, as well as on the knees behind the Telrad. There is only one hex nut on the inside of the OTA, so the ball has some freedom of motion around its position as it is being pushed or pulled around. It is also rotating around that axis with some friction. At first, I thought about fixing that with another nut on the outside, but after the thorough field testing decided to keep it rocking free as it is now.

Counterweight

With the vast variety of accessories, starting from a different weight eyepieces, the OTA center of gravity might shift considerably towards the open end. Which is often perceived as the altitude bearing failure and usually addressed by a sort of adjustable braking system over the altitude semi-axes hubs, plus a habit of applying and undoing it. In my opinion  that just consumes observing time and neglects the dobsonian construction principle: "simplicity - first".

Luckily enough the Zhumell Dob OTA material is a plain steel which is naturally ferrous. The solution came in a snap. An old steel (also ferrous) counterweight scavenged from my old cheap refractor mount (4.2 lbs), a couple of strong neodymium magnets harvested from a broken hard drive, and a stripe of blue masking tape for scratches prevention - all were sticking to each other almost by themselves.

Carrying handles

This telescope is quite heavy and bulky to move around. So I've decided to add some handles to make life easier. The most typical approach is to bolt down some furniture handles to the OTA. But I don't like such an idea because the steel of the tube is quite flexible and will require a lot of back support (from inside) to safely accept carrying handles. Also, it's quite an additional weight.

My perfect solution was to add two rings of 1/2 inch thick climbing rope, loosely wrapping the OTA above and below the altitude trunnions. The tiny bungee cord between is just keeping the lower ring from sliding and allows quick disconnect. It's not for carrying!

I can grab both ropes with one or two hands on any side of the OTA and reliably hold and carry it in any position from horizontal to vertical conveniently and securely.

Star charts

I'm not a big fun of using paper star charts of any kind. They are bulky, prone to damage in the field, require light source, and there are too many of them necessary to cover all my interests for a single night. Instead of paper I'm using the Astromist hanheld planetarium software. At the moment - on my Windows Mobile 6.5 phone, and on my old but still functional Palm OS PDA - in the past (by the way, there are iPhone and iPad versions of Astromist are available from the same developer, but nothing comparable for Android or Windows Phone 7 yet - very sad). Astromist is the best pocket star atlas and observations planning software available for amateur astronomers of the planet Earth, period. Highly recommended!

EDIT: So, by now (2016) I've made one for Android myself with a friend. See DSO Planner - the best handheld digital star chart ever built!