Advice on creating an adapter

[Hans Tucker]

As a Winter project I have decided to see if I can make an unholy alliance of a Askar ACL200 f4 lens with a STF-8300C to create a widefield light imaging setup. Apparently the ACL200 has a Back-Focus of 55mm and the Sensor on the STF sits back 17.5mm so I am assuming that I need an adapter of around 37.5mm.

How critical is the length of the adapter?

Is it advised to go longer or shorter or exact?

Sorry in advance for the noob question.

I gather there are no off the shelf options so I will need to get Precise Parts to manufacture this adapter.

[AdamJL]

Hi Hans

That's a fairly common back focus distance. Just get a 21mm and 16.5mm adapter. I'm guessing the camera has an M42 thread? (I looked but couldn't see info on it)

edit:
e.g.

21mm (screws into the camera and the below)
https://www.bintel.com.au/product/zwo-t2-t2-extension-21mm/?v=322b26af01d5

16.5mm (M48 side screws into the scope and M42 screws into the above)
https://www.bintel.com.au/product/zwo-m42-m48-16-5mm/?v=322b26af01d5

[Stefan Buda]

Better a bit shorter, in case "exact" can't quite reach infinity focus.

Should be able to do better than Precise Parts pricewise.

[gregbradley]

Get Joshua Bunn to make you something. Half the price, similar quality and a third the wait.

He's made several adapters for me. Very good. Precise Parts are good but they place the onus on you with their design an adapter web system. No personal contact so any errors its on you. Precise Parts used to have personal contact (via email) that helped with the design in case you were making a mistake. Josh gives personal contact so errors are unlikely. You support a local, he's half the price and 3 times as fast and the result is more certain.

Greg.

[Andy01]

+1 Stefan Buda above - based in Melbourne - does amazing, very precise work & has reasonable pricing. :thumbsup:

[Peter Ward]

Ditto. Josh's work is excellent.

[Hans Tucker]

Thanks all for the advice and recommendations.:thumbsup:

[Joshua Bunn]

Thank you Peter and Greg!


Hans, I'd gladly make you one, you can contact me if you like, on 0428650851 or email me at scastrophotography@outlook.com
Happy to help out.