CC Collimation help needed

[WbRaDy]

Hello All

I have  a couple of questions i cant seem to find an answer too while collimating my scope and i am looking for advice on which/what route to take, please bear with me while i try to explain 😐

I have the StellaLyra F12 CC which comes with 50mm + 25mm + 25mm extension rings, when im collimatiing i use a cheshire and bare scope and focuser i.e no extension rings and i seem to get this looking spot on but when the 4 extensions are added as i need with the planetary camera the collimation is out with the cheshire, while the eyepiece mark was bang centre of the secondary centre ring beforehand it is now half way out of that ring, im pretty sure its the focuser not seating right after the rings are added, so first question is would a tilt adapter which i do now have fitted be the solution to this "shift"? maybe after doing the first collimation then add the rings would i be able to bring that eyepiece mark back again using the tilt adapter?, i have never used a tilt adapter before so not sure of the actual process.

Also there is a lot of movement in the eyepiece holder when the thumbscrews are tightened up on the cameras 2 inch adapter, unfortunately the standard focuser does not have T2 threads or any for that matter for the camera to be directly attached so can anyone recommend a solution to this without forking out on a new focuser? im sure that would have to be an option sooner or later and told the baader is probably the way to go..

Thanks for reading and if i have not explained myself please shout out..

 

Edited February 17, 2023 by WbRaDy

[Carbon Brush]

I would be good to separate focus droop on loading from a focusser that doesn't point down the tube centre.

Set up the collimation and then change scope orientation. Two separate tests.
Horizon to zenith. Tube horizontal but rotate in the rings.

In either case you are looking for movement.
Horizon to zenith change tends to indicate something sagging under the weight.
Rotation in the rings tends to indicate some side to side play in the focusser.

I have yet to try collimating a CC. But on a standard newt, or a Mak newt I find a simple laser useful.
Just look at where the reflected spot lands and either move the scope as described, or apply gently finger pressure to parts.

HTH, David.

[pipnina]

58 minutes ago, Carbon Brush said:

I would be good to separate focus droop on loading from a focusser that doesn't point down the tube centre.

Set up the collimation and then change scope orientation. Two separate tests.
Horizon to zenith. Tube horizontal but rotate in the rings.

In either case you are looking for movement.
Horizon to zenith change tends to indicate something sagging under the weight.
Rotation in the rings tends to indicate some side to side play in the focusser.

I have yet to try collimating a CC. But on a standard newt, or a Mak newt I find a simple laser useful.
Just look at where the reflected spot lands and either move the scope as described, or apply gently finger pressure to parts.

HTH, David.

I think lasers can't collimate cassegrain telescopes fully, as your beam goes from focuser to secondary, then when the secondary is properly collimated the beam comes back to your laser source. I.e. you get no reflection onto the primary.

I think there are multi-beam tools that let you collimate cassegrain telescopes with a focuser-mounted tool, like this one: https://www.teleskop-express.de/shop/product_info.php/info/p11188_TS-Optics-2--LED-Collimator-for-RC-Telescopes-and-all-other-Types-of-Telescopes.html

But like you I have little experience collimating a cassegrain scope, so I can only offer up the little knowledge I have...

This might be some help, even though a CC and an RC are a bit different:

 

[dweller25]

Step 1 in the below web site may help determine if the focuser is orthogonal, if not you can use the tilt plate to correct it……

https://www.hnsky.org/RC_collimation.htm

Edited February 17, 2023 by dweller25

[WbRaDy]

Thanks for the information guys, i dont have a problem collimating the scope without laser devices, i did try one previously but had no luck with this scope, my question is could the re-alignment of the focuser be done with the tilt adapter after all the extension rings are fitted? once the focuser is fitted it will not be rotated so is in a fixed point.

So basicly after collimating the scope and focuser with no extension rings attached i end up with this..

 

After fitting all four of the extension rings and focuser i end up with this...

So could this be brought back to image one using the tilt adapter?

 

Thanks for your patience guys..

 

[WbRaDy]

Sorry Dweller25 i just noticed your last comment, tilt adapter it is...👍