This might be a daft question... M48 Thread

[daz]

So, the flattener on the Sky-watcher ED72 has a male M48 thread. My Atik One OAG has a female T2 (M42?) thread. So far so good...  What I am after is an adapter that will thread on the INSIDE of the flattener (i.e. a male thread) and then a male thread on the T2 side.

Why, I hear you ask...

It's the old 55mm problem. The flattener has a back focus of 55mm. My Atik One CCD sits ~28mm from the front of the case, and the OAG is 24mm deep - giving 52mm. If I use the M48-T2 adapter from FLO, it adds 10mm to the train i.e. 62mm. Which I'm pretty sure will be too much.

So, me and my tiny brain think I need some sort of adapter that threads on the inside of the M48 thread of the flattener - but I don't know what size that is! 

Does any know what this may be - or have another suggestion??

[vlaiv]

I'm not quite following why do you need male thread on adapter side - if it already has male M48?

In any case, see if this one fits you - it has only 3.5mm optical path.

https://www.teleskop-express.de/shop/product_info.php/info/p3504_TS-Optics-Adaptor-from-M48x0-75-to-T2---low-profile.html

Alternative is of course to get different OAG - maybe this one:

https://www.teleskop-express.de/shop/product_info.php/info/p8319_TS-Optics-Off-Axis-Guider-TSOAG16---stable---length-16-mm.html

It is only 16mm of optical path and you can add this:

https://www.teleskop-express.de/shop/product_info.php/info/p1649_T2-Ring-for-TS-Off-Axis-Guider-TSOAG9-and-TSOAG16.html

to complete the setup as you need it.