Used Nexstar 6se - couple of questions

[Wanderers]

I've bought a very cheap 6se (cheap because the collector plate needs a good clean and one leg is missing its wing nut.)

On close inspection today I noticed the secondary appeared to be a little loose. I carefully tightened it in its thread.  I noticed an external thread around the outside of the internal thread I tightened the secondary into. Now I'm wondering if I'm missing a ring to secure the secondary in place?

I'm also wondering if the collimation will be out as the secondary has been moved?

 

[Wanderers]

I meant corrector!

[Stu]

8 hours ago, Wanderers said:

I meant corrector!

Some pictures may help explain what you are asking.

[Mr Spock]

Front of the 6se should look like this:

As for collimation, a good start is to look down the tube. Place it 2-3 metres away and look down the tube from the corrector end. What you should see are concentric circles. Once you have those concentric circles you are ready to do a star test:

Adjust the screws until it is perfect.

[Wanderers]

4 hours ago, Stu said:

Some pictures may help explain what you are asking.

this confirms what i thought. I'm missing the ring that obviously secures the secondary in place. 

Is it possible to order such parts?

[LandyJon]

12 hours ago, Wanderers said:

I carefully tightened it in its thread

I didnt think the secondary screwed in to a thread ?  Is it held in place then ?

I had a 6SE but don't recall removing the secondary, the Edge 9.25 has the same as pictured above, the secondary slots in with a peg to achieve correct rotation position, then the retaining ring screws down to hold it in place.

A photo of what you've got would help, there may be earlier versions which were different to the above image, certainly fastar compatibility would have changed the way the secondary mounted if yours is pre-fastar.

As for buying spares a quick Google found nothing, but a quick call to FLO or Rother Valley, one or other may help you find the part.

Edit : Oh and collimation will need to be checked either way once you've sorted it, these SCTs hold collimation pretty well, I work on the idea mounting and dismounting and carefully packing away etc is all good but take it for a drive and you should check its still aligned.

Also cleaning the corrector is easy enough, even if it needs removing, just be sure to mark the orientation so it goes back in exactly the way round it came out from.

Edited March 20 by LandyJon

[Cosmic Geoff]

1 hour ago, LandyJon said:

A photo of what you've got would help,

If a part is missing, the likelihood of finding a replacement is probably nil, unless you can acquire another scrap C6. Or have a part made, e,g by 3d printing.

[Wanderers]

I've just bought a 6se on ebay with smashed corrector. Fortunately the secondary is OK as is the retaining ring. It cost £100 but everything else still works so I'm going to try and recoup my losses!

[Wanderers]

Thanks everyone for all your help and advice.

The two 6se's have cost a total of £300 so I've done OK, especially if I can sell some parts.

[LandyJon]

On 20/03/2024 at 15:56, Wanderers said:

I've just bought a 6se on ebay with smashed corrector

Remember the corrector, primary and secondary are all matched at manufacture and oriented for best performance so try to use all 3 from the same scope and maintain their orientation through any dismantle and reassembly.

Hope you get something that works well at the end, I liked mine, they're a good little scope.