Friday, April 18, 2014

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!!