Classical Cassegrain Collimation

[bosun21]

I just bought a new classical Cassegrain which was delivered today. The collimation was way out and the primary mirror was not tightened and would shift as you picked the scope up to place onto the mount. I am proficient with collimation on a Newtonian but it’s a different ballgame here. I think I’ll have to contact FLO in the morning to see where we go from here as this is useless at present.

[Knighty2112]

I had the same when I got my CC6. Struggled to collimate it with a laser, cheshire and a collimation cap. Got one of these from TS Optics and got it sorted out within about 15 minutes of using it.

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

 

[bosun21]

I’ve been looking at them myself but I didn’t want to throw good money after bad. I see FLO has these in stock at the minute. I keep chasing my tail with my Hotech, Cheshire and cap. I get what I think is close then a half turn to oblivion. So you recommend one of the TS RCKoli?. My new scope buzz has turned to despair 😩 

[Knighty2112]

7 minutes ago, bosun21 said:

I’ve been looking at them myself but I didn’t want to throw good money after bad. I see FLO has these in stock at the minute. I keep chasing my tail with my Hotech, Cheshire and cap. I get what I think is close then a half turn to oblivion. So you recommend one of the TS RCKoli?. My new scope buzz has turned to despair 😩 

Worked for me and I’m no expert at collimation. 

[Knighty2112]

I would say also that the scope does need to be well cooled down to get the best views from it, so make sure that it is cooled down before you observe with it even when collimated. One reason I prefer ‘fracs really is you can get on with using them pretty much from taking them out.  

[Knighty2112]

Remember when you collimate the scope just have the focuser attached to use the device. Don’t have any extension tubes fitted that you might need to achieve focus with any diagonals/EP’s fitted, and have the focuser wound fully in to perform collimation. 
 

As there is no manual sent out with the scope (at least I never got one), then the below link gives the manual for the Orion CC version, which apart from branding is exactly the same as the Stellalyra version;

https://www.telescope.com/assets/product_files/instructions/IN621_Classical_Cassegrains.pdf

[bosun21]

Yes I have removed the extension and wound the focuser in. No there’s still no manual and still has a black dovetail!. I was expecting it to be red as shown in the FLO website. With the primary being loose on arrival I had no basis to work from. I wish I had bought the 150 Maksutov now.

[dweller25]

You can get a good level of collimation indoors by looking at all the reflections down the front of the tube and then adjusting the loose primary to get concentric circles.

Then fine tune at high power on a star.

Or return it and get a 4” APO 👍

Edited July 21, 2022 by dweller25

[JeremyS]

5 hours ago, bosun21 said:

Yes I have removed the extension and wound the focuser in. No there’s still no manual and still has a black dovetail!. I was expecting it to be red as shown in the FLO website. With the primary being loose on arrival I had no basis to work from. I wish I had bought the 150 Maksutov now.

Not right that the primary was loose. Is it still? Are you sure that in tightening it (if you have) you’ve upset it’s ability to collimate?

[bosun21]

8 minutes ago, JeremyS said:

Not right that the primary was loose. Is it still? Are you sure that in tightening it (if you have) you’ve upset it’s ability to collimate?

No it’s perfectly fine and can still be collimated. The primary has 3 x locking screws and 3 x collimation screws. I have got it pretty close but not close enough for planetary photography, which is the primary reason I bought it.

[bosun21]

25 minutes ago, dweller25 said:

You can get a good level of collimation indoors by looking at all the reflections down the front of the tube and then adjusting the loose primary to get concentric circles.

Then fine tune at high power on a star.

Or return it and get a 4” APO 👍

That’s what I have done, but if the secondary hyperbolic mirror is out then that contributes to non concentric circles also 😱

[bosun21]

I’m just waiting for Steve at @FLO to get back to me as he said that they would collect it and collimate it on the bench for me. This seems like the best way forward for all.

[FLO]

58 minutes ago, bosun21 said:

I’m just waiting for Steve at @FLO to get back to me as he said that they would collect it and collimate it on the bench for me. This seems like the best way forward for all.

I replied four hours ago at 11am 🙂 

We offered to collect and collimate the telescope, or accept it back for refund via our 30-day return policy. You replied saying you prefer the former. We now only need know which weekday is best for us to send DPD? 

HTH, 

Steve 

[FLO]

Ah, I see you recently started another separate conversation at our Helpdesk.

No problem. We'll arrange collection for tomorrow 🙂