Skip to main content

Improving the Celestron 70az

Recently i was looking to buy a second smaller telescope, ideal for traveling. I concluded on Celestrron Travel scope 70 that has the best value for money. During my research about the quality and the characteristics of the scope, i  came up to a page that was commenting how to improve the quality of the scope.

Here are some thoughts about my scope:

- The quality of the tube is slightly better, but still it has some issues.
- You also have some bolts inside the tube, but not  many as the travelscope.
- Collimation is an issue also here. You should use a collimator to fix this. However, in my case i wanted to avoid buying anything new.
- Lenses are not blackened (neither in eyepieces)

Collimation without tools:

Collimation is usually not an important issue in refractor telescopes compared with the reflector, but it can improve the views and the experience of star gazing. You have to disassemble the telescope without caution. Take care the lenses!

The easiest way to fix the collimation issue was to focus on a bright point (star or something small) with 10mm eyepiece or less and adjust the lenses. In my case the problem was on the ring that keeps the two lenses together (the objective lens). The ring was too tight screwed, i relaxed it a bit and the viewing quality was improved.

Lenses blackening 

The second step of improvement was the blackening of the edges of lenses. Astromaster telescopes are not expensive telescopes, thus you should not expect good premium lenses. The  first step was to disassemble the tube and remove the lenses:

Lenses of the Astromaster 70 before blackening.
Lenses of the Astromaster 70 before blackening.


The second step is to paint black the edges. Note that you have to paint even the small space between different edges, or else you will still have some light scattering around. Note the next picture:

Painting black the edges of the lenses. You have to completely black the lenses because some light will scatter around.
Painting black the edges of the lenses. You have to completely black the lenses because some light will scatter around.


After finishing the painting we have to put them back in the tube. Note that is extremely important that you keep the parts in the right order and also facing the right way, or you are risking damage to the glass.

After blackening the lenses of my telescopes.
After blackening the lenses of my telescopes.

After finishing with the tube's lenses you can move on on the eyepieces. Unfortunately, you can't disassemble most of the eyepieces, but you can disassemble the 20mm bundled with the telescope. Again, here you must be careful with the dissemble to avoid  damaging the lenses:


Parts of the 20mm eyepiece coming with the Astromaster telescope. You can blacken the two lenses.
Parts of the 20mm eyepiece coming with the Astromaster telescope. You can blacken the two lenses.


Then, you should pack everything and you should test everything during the day before actual live testing on the night. It is not easy to 'debug' the lenses in the night without light. I suggest to test lenses with a different part each time. For example, you can use your favorite unmodified eyepiece with modified telescope tube to test the result:


Celestron Astromaster with 2X magnifier and 30mm eyepiece.
Celestron Astromaster with 2X magnifier and 30mm eyepiece.

Happy star gazing!!



Popular posts from this blog

Processing Milky Way in RawTherapee

This text is an analysis of a video I did some months ago how to process photos of our Milky Way in RawTherapee. You can find the picture here . The photo was taken by wiegemalt. This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. Editing: Step 1: Fixing lighting The first thing someone notices when opening the picture is the extreme noise due to high ISO used (1600 - check the picture on the right). The first thought is to de-noise the picture, however, if you do that you are going to loose the details of the night sky. The main reason for the high noise is the additional exposure Rawtherapee adds when the 'Auto' button is pressed. In particular, the RT adds +2.4 EV to equalize the picture. This is Wrong! What we want is to keep the noise down and at the same time bring the stars up. That's why we are going to play with the Tone Curve of the RT. To adjust the light properly we increase the cont

Static linking with gcc and g++

In this tutorial, we will explain what the static linking is, how this affect the size of final binary, and why statically linking with g++ sometimes is pain. By definition, a statically compiled binary is a group of programmer ‘s routines, external functions, and variables which are packed into the final binary executable. The compiler or the linker produces the final object and embeds all the functions and variables and the linking phase.  There are two reasons of using dynamic linking and shared libraries: 1) Avoid creating a huge binary, if all the programs use a standard set of libraries why not having the operating system providing to them 2) Compatibility on operating system and machine dependant characteristics: sometimes the libraries must be implemented based on the architecture or the operating system and using dynamic linking is an easy way to avoid this catch. On the other hand, static linking is the ideal way of distributing one software product, paying

TrueNAS core TIPS

And for completion here are some tips in general for NAS:   Use backup. NAS is not a backup. It is a part of backup, never forget this. Always have backup on a different media (or different NAS) and off site if possible! Use hard disks and SSDs from different vendors always. You may be unlucky and receive media from a problematic batch and have multiple failures during the recovery. Use RaidZ2 or RAID6 or better to reduce the risk of completely losing the data. Use high quality PSU. A NAS runs all the time, so selecting PSUs with GOLD certification or better can reduce your power consumption. Use UPS or at least an AVR. It is a very bad idea to stop a NAS system without proper shutdown procedure. Don't overuse the NAS server with multiple VMs/docker instances/Jain instances. Keep it simple! Here are some tips and tricks from my TrueNAS home NAS server. In my previous post I analyzed the reasons for using TrueNAS instead of Linux distributions (ZFS, stability etc). After two months