Designs for PST rear etalon adaptors?

[Merlin66]

I'm getting quotes for a rear etalon adaptor for the Stage 2 PST mod.

Many guys just use the SCT>2" female and use teflon tape to fix the thread differences....

I'd like to see a proper M50 x 1 adaptor....

The question is:

What would be the prefered end connection?

I've used T threads/ SCT male/ 2" female in the past and would think the SCT male or the T thread would be popular????

To get a focuser into the available space ( 200mm less the BF10, say 200-80= 120mm) can be a problem. I've used the Baader Helical focuser which fits onto the T thread...

So, which adaptor would you like to see if you replaced the one you have or would like a new one.

Let me know and I'll get some manufactured.

Ken

[Andrew*]

Hi Ken,

This would be great, because of where the M50 thread is placed - the ideal adaptor needs to clear the etalon, but not be too long as to restrict spacing.

IMHO there are two obvious ways of focusing:

- Low profile SCT focuser. I'm about to try this way, but I'm not 100% confident of the spacing. Eyepieces and cameras have very different focus positions, and an SCT focuser uses a lot of space, even the low profile ones.

- T-thread helical focuser. The problems here can be finding an adaptor which clears the etalon.

I think the options of male T or SCT would cover most needs nicely.

Andrew

[Merlin66]

I think the M50 > SCT is probably the most versatile option; you could use the SCT focuser, or add an SCT >T thread adaptor and then T spacers and a helical focuser.

(BTW I used a SCT focuser successfully on a mod a couple of years ago)

[Merlin66]

Found the images of the EC90 set-up.

Based on a Surplus Shed 90mm objective, wooden (MDF) square tube and the PST etalon/ SCT focuser etc.

[Andrew*]

Nice work - the adaptor looks the business.

Yes, of course you can adapt SCT-T easily - the SCT version makes most sense.

Andrew

[NickH]

Similar to mine, I have the AE rear SCT adapter and the ambermile front piece, with a spacer at the back to get the 200mm behind the AE unit...to the BF10, and anyone who's has a looksie, will know it works rather well.

Ken...you'll clean up with those adapters

[spaceboy]

Did anything ever come of this Ken ? or is there now an alternative already out there 7 years on ?

[Merlin66]

No, not commercially. Not enough demand.......

I have made a few of the M50 to T thread adaptors over the years and still use one on my Stage 2 mod with a Borg helical focuser.

The local machine shop seems to be the answer.