why are my stars so crazy?

[Nova2000]

hi all

last night i was basically trying to know stuff better by setting up the Astro clubs gear. GSO 10 f4 newt astrograph on a neq6.

i did the collimation properly and i knew that the balance was not good and so the images trailed a bit . just because i setup everything as practice so i don't waste time when i take the gear to dark sites i clicked 20x30sec shots of m45 .

i reliazed that something was off about the stars . i was using a coma corrector and i doubt the collimator 

As when i turned the collimator during the collimation process so i can see the lazer dot the beam inside the scope shifted .

I think the collimator needs to be aligned? is so how do i do it?

 

[alacant]

22 minutes ago, Nova2000 said:

a coma corrector

Hi

The camera is tilted and is too close to the coma corrector. Probably best to collimate again but using a Cheshire sight tube instead. If you have a centre mark of the primary mirror, a Cheshire with cross hairs would be even better.

If you post camera and cc information, we may be able to help further.

If you can't get a Cheshire, have a go at the laser.

Cheers and clear skies.

Edited February 18, 2020 by alacant

[Nova2000]

Hi my camera is a Canon 700d . I use the GSO coma corrector .I use the 2inch barrel with the tring and insert it in the coma corrector.

 

[alacant]

Hi

OK, so you need:

camera - t ring - 15mm (at least) spacer - coma corrector - focuser

Your starting target is 75mm from camera sensor to shoulder of the cc; without the m48 to t2 adaptor.

What do you have? Maybe a photo would be better.

Edited February 18, 2020 by alacant

[Nova2000]

This are is the GSO coma corrector we have and the the 1.25 inch adapter. I don't use any other spacer other than these 2 products. 

[alacant]

20 hours ago, Nova2000 said:

don't use any other spacer

This is why your stars are poor; you do not have the magic 75mm backfocus.

You need a 15mm t2 extension. Get a set maybe? You need this t-ring.

So you should now have: Camera - t ring - 15mm extension tube - m48 to t2 adaptor - cc - telescope focuser.

Note, you must unscrew the eyepiece holder form the cc. You do not need the 1.25 adaptor.

Here it is setup ready to mount on our 700d. Otherwise please post a photo of your setup.

Edited February 19, 2020 by alacant

[Nova2000]

Very sorry for the late reply , didn't go to the Astro club . Now I have the images of the tring and coma corrector. It's a 2inch barrel screwed onto the tring . I feel the porblem was with coma corrector but now I'm interested in the 75mm backfocus which I feel is also wrong in our setup.

One picture is with the tring and adapter inserted into the coma corrector. 

[alacant]

24 minutes ago, Nova2000 said:

tring and adapter inserted into the coma corrector. 

Ok. Remove the t ring and unscrew the part in which you had it inserted. This part is only for visual use if you are going to look through the telescope. It is for inserting an eyepiece. Remove it.

next, look back at this post:

Attach your camera and insert the assembly into the focuser of your telescope.

That's it.

HTH

[ollypenrice]

Back on collimating of lasers for a second, there is an even easier way to make vee blocks though they won't look very professional!  Just get a flat piece of wood and four 6 inch nails. Bang in one pair of nails to make an X shape. That's your first vee. Now make a second vee an appropriate distance away. Sit the laser in these and turn it. This will give a perfectly accurate result.

Don't expect it to be easy to get this scope into perfect collimation and orthogonality. It is notoriously difficult because fast optics and budget mechanical construction are not natural bedfellows. However, getting the right distances will be a big help.

Olly

 

[Nova2000]

12 minutes ago, ollypenrice said:

Back on collimating of lasers for a second, there is an even easier way to make vee blocks though they won't look very professional!  Just get a flat piece of wood and four 6 inch nails. Bang in one pair of nails to make an X shape. That's your first vee. Now make a second vee an appropriate distance away. Sit the laser in these and turn it. This will give a perfectly accurate result.

Don't expect it to be easy to get this scope into perfect collimation and orthogonality. It is notoriously difficult because fast optics and budget mechanical construction are not natural bedfellows. However, getting the right distances will be a big help.

Olly

 

Thank you olly . I was searching for information on how to collimate the laser will try this .

18 hours ago, alacant said:

 

Attach your camera and insert the assembly into the focuser of your telescope.

That's it.

HTH

Thanks for the help and opening my eyes to what we were were doing wrong with the coma corrector . 

Now I really understand why many prefer Refractors

clear skies