Stars with tails - tilt issue? *help* Generic equipment discussions · Buyman3375 · ... · 50 · 855 · 19

Buyman3375:
Well...

This is where I fear I am going to lose you. Because of my incompentence. The first mirror was only glued to the stalk with a silicone from the inside of the of the stalk, not underneath where it touches the mirror, nor on the outside.

When I wanted to fix it in place, I played with a glue gun on an example first and realized that the dew heater would soften the glue and I feared that it might loosen during the heating outside and fall into the tube. Out of fear, I had the "great" idea to glue it with 3 different silicones. I used one for the direct contact to the mirror, one for the inside of the stalk to the mirror and one on the outside of the stalk. It doesn't look terrible and I did a good job at keeping it at a minimum. But I am slowly having this creeping feeling, that this might have caused my dilemma... Please tell me it can't be...

andrea tasselli:

Buyman3375:
I will try that tonight.

I'm located in PA and my temperature ranges nowadays from  25F - 50F degrees. During the day, we recently had it all the way up to 72F. And when I'm not storing it in the open shed, due to rain, wind or snow, I have it outside at the sme spot - under Telegizmo's!

CT scopes have 3 fans behind the primary mirror cell, Have you tried using them at all? Have you tried see what happens when they are running?

Pretty cold in PA, btw...

Sean Mc:
Do you have any spacers in your imaging train?

andrea tasselli:
Laser is only good for a secondary centering on the primary (and coarse primary collimation). Beyond  that is either autocollimator or star test.

andrea tasselli:
I don't know, still cheaper than the competition...

Farpoint 2 Inch Autocollimator – FarpointAstro

Buyman3375:

andrea tasselli:
The autocollimator works on different principles and the aim is reached by aligning the multiple reflections of the center marker (off the mirror in the autocollimator) of the primary onto themselves, so its accuracy is unsurpassed for a fast system such as yours. And mine, since that is what I use.

That makes sense. I didn't think of the multiple reflections. Sometimes, I should use my brain first before opening my mouth.

Once more: Thanks a bunch!

andrea tasselli:
Sadly, no.  You can try your luck with the more expensive (but very good!) ones:
CATSEYE Collimation Main Page Frameset File

andrea tasselli:
The length depends on the distance between the flange of the focuser and the sensor, in your case 55mm. You can get the cheaper one and add spacers to achieve the same effect.

The triangle marker (which I also have) is only helpful if you can illuminate it and it is invaluable if you were to collimate in the dark with a strong illumination source. In bright daylight isn't that an advantage but you can score brownie points if you have one!

andrea tasselli:
As far as I know, there is no thread.

andrea tasselli:
There exist what are known as focus extenders (actually they should be supplied with the focuser). The fit into a 2" clamp flange and  allows to reach focus further from the maximum focuser travel position. You would normally mark or leave the focuser at its position when in focus and add those 55 of extension. Any 2" tube section can in fact be used for the same purpose as long as the ends are parallel to each other.

As examples (the last one is probably the better one so anything close to that, with 2" extension and adding a couple of parafocal rings should do the trick):

2inch Telescope Eyepiece Focusing Device Extension Tube for Astronomical | eBay

Astro Essentials 2" 35mm Focus Extension Tube | First Light Optics