Basic t-ring issue

[rnobleeddy]

Until the 130PDS is back in stock I'm trying to take a few shots of the moon with my old reflector telescope.

I've successfully hooked up a 2x Barlow(https://www.firstlightoptics.com/barlows/astro-essentials-125-2x-barlow-with-t-thread.html) with a Nikon t-ring (https://www.ebay.co.uk/itm/T-Ring-for-Nikon/293525566844?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649) to allow me to take photos of the moon with my Nikon D3000.

Realizing that particular camera will be awful to use for more serious imaging, I got a second had astro-modded Canon 450D in preparation. I then decided I ought to make sure it works, so bought a https://www.amazon.co.uk/Celestron-93419-Adapter-Digital-Cameras/dp/B000237C9M t-ring adapter thinking I could just swap the camera over. 

The issue is that the Barlow won't screw in to the Celestron t-ring adapter (specifically, the same part of the barlow that screws in to the Nikon adapter fine). It starts to tighten, but is a tight fit and after maybe 1/4 of a turn it won't turn anymore. 

I realize that it's hard to diagnose this kind of issue via me writing text alone, but just wanted a sense check I don't have anything obviously wrong? 

I realize this is low quality kit, but the telescope I have uses 1.25" kit and the scope I intend to buy uses 2", so there wasn't much point in getting high quality kit. Even at this price I imagine things should screw together?!

Edited May 28, 2020 by rnobleeddy

[Cornelius Varley]

All of the t-threads should be the same (M42x0.75mm). It might be possible to visually compare the Nikon and EOS t-rings to see if there is an obvious difference between the two or maybe to look for anything stopping the barlow screwing on to the EOS t-ring.

[rnobleeddy]

Thanks, 

There's no obvious problem, it feels like the threads are just incompatible. Given the Barlow and the Nikon t-ring were obtained separately and work fine, I presume it's the canon t-ring and so I've ordered a different brand.

Realize this question may have seemed obvious, but it's good to get reassurance that I'm not missing anything obvious.

I expect I'll be posting more here in due course, but hopefully not about screwing threads together!