Ambiguous threads and adaptors

[Leeps]

I'm trying to put together a modest rig with a D5100 that I've modded and my 200p newt scope. When I removed my hot mirror, I bought an external 2" ZWO astro replacement, expecting to be able to mount this in the scope and use the T ring adaptor in as normal. I'm a little frustrated tonight having finally received the thing, and it's not fitting on the T-threads (obviously that's not standard 2"...) 

Is there an adaptor I need? Is there a specific name for the 2" thread? It fits my 2" skywatcher eyepiece (that I also need an extension tube for, but don't know how to describe the thread!)

To complicate things I also have another extension tube that came with my Nikon-T adapter that seems to be larger than 1.25" but doesn't match up with anything else! There's also the 2" holder on the scope which is another thread altogether 🙃

From the below picture:

I would like the filter in between A and B (or C), and the only thing it fits to is D (which I need an extension tube to focus with!)

I'm guessing I need an embiggener from A to filter, and then an ensmallener back to B again 🙃

 

Thanks for any help, I'm lost!

 

 

[Leeps]

For anyone that might find this thread, this post here is enlightening: https://agenaastro.com/articles/guides/miscellaneous/astronomy-threads-explained.html

 

It seems my T-thread is a M42 x  0.75, and the "2 inch" thread is M48 x 0.75.

 

I think I can buy adaptors / extension tubes around this info. 

 

Edited March 5, 2020 by Leeps

[Geoff Lister]

Hello Leeps,

Your A & B look something like these 2" & 1.25" eyepiece adaptors from my 250PX

Your C looks like a combination of the top section of my T to 1.25" adaptor and my x2 Barlow. I have found that I need the T-adaptor + x2 Barlow to get enough inwards focus on my 250PX.

This is how I use my D3200 in place of a 1.25" eyepiece.

Geoff

 

[Leeps]

Thanks for the hints Geoff! In your setup, I don't think it'd be possible to use this 2" filter, the same as mine - that's whats a little confusing to me. Does your 2" adapter unscrew to reveal a thread, between the dovetail end and the barrel? 

[Geoff Lister]

23 hours ago, Leeps said:

Does your 2" adapter unscrew to reveal a thread, between the dovetail end and the barrel? 

I have just taken some photos

Draw tube extended with 1.25" eyepiece adaptor clamp

Eyepiece adaptor clamp - screws engage on dovetail slope

Draw tube end with internal thread

Draw tube end clamp ring

clamping ring front and back

I hope this helps.

Geoff

 

[Leeps]

I ended up solving this with this adaptor: https://www.ebay.co.uk/itm/SVBONY-SV125-Astronomical-Camera-Adapter-Bracket-2-T-Mount-for-SLR-Camera-UK/163919085178?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2649

This allowed me to mount the filter at one end, and adapt to the T mount on the other. Seems to work great!