2" Diagonals

[furyz (Kristian)]

Had a question about diagonals, I am looking to move towards 2" diagonals and eyepieces and wanted to see what diagonals people would recommend.

I read the diagonal comparison guide on Cloudynights. I know the prism diagonals are especially good at planetary and ultimately I would love a Baader 2" Zeiss Prism diagonal, maybe one day when I win the lottery.

Until I win the lottery, I need to be a bit more realistic. I currently have my Celestron Star Diagonal that came with my C8. Its a solid workhorse, and its a great small prism diagonal. My only gripe with it, is that the position of its thumbscrews can get in the way of some of my chunkier Baader eyepieces. So I wouldn't mind a diagonal that has twist locks. Either a Baader clicklock or something similar.

Some of the more cost effective options seem to be dielectric coated mirror diagonals. The Celestron 2" mirror diagonal with twist locks or the Orion 2" mirror diagonal which has been rebranded by many other manufacturers including Bintel. From the shape and design of the diagonal case, I think the Celestron, Orion, Bintel, etc are all made by the same manufacturer probably in China and simply rebranded with some minor changes to the case or colour of the twist lock rings.

https://www.baader-planetarium.com/e...al-mirror.html
https://www.celestron.com/products/d...ith-twist-lock
https://www.telescope.com/Orion-2-Tw...l/p/116405.uts
https://www.bintel.com.au/product/bi...ar-diagonal-2/

So my question is, has anyone used any of these 2" mirror diagonals and what is their opinion on them as an upgrade from a Celestron 1.25" Star Diagonal?

My other option is scrap the idea of 2" and get a more cost effective Baader 1.25" Zeiss Prism Diagonal. I get rid of the thumb screws, and I get a really good performing prism diagonal, especially for planetary viewing.

Interestingly, there once existed a Celestron 2" Prism Diagonal, which appears to have been a Baader rebrand. https://www.cloudynights.com/topic/5...zeiss-2-prism/

[Hoges (John)]

I recently got the Bintel twistlock 2". Visually it seems fine but I am not convinced about the twist lock mechanism. Some eyepieces seem to fit fine and snug up easily, but others need a fair bit of effort to lock in. I don't think I would buy one again. I should have snaffled the Baader twist lock that came up in the buy and sell recently!

[The_bluester (Paul)]

I had a Bintel 2" mirror diagonal on my old C925 and it was a perfectly good piece of kit. But whatever you do fit, make sure that it makes rotating the diagonal on the back of the scope easy. Initially I bought the "SCT thread" version of the diagonal I was using, which screwed straight on to the rear cell of the OTA, but rotating it was a royal pain. A 2" extension tube with the right SCT thread and a compression fitting at the other end and a 2" nosepiece on the scope side of the diagonal was much better.

[furyz (Kristian)]

Interesting, thanks for the replies. So the twistlock on the Bintel is hit or miss and the SCT rear cell thread version can be a pain to rotate.

So already a Baader clicklock mechanism is sounding like a more reliable choice if I can justify the premium on some form of Baader diagonal.

Yeah I saw that Baader 2" mirror diagonal that popped up recently in the classifieds and I regret not looking at it more closely. At the time I was more locked into the idea of getting a prism diagonal as any visual viewing I would do is most likely to be planetary, anything DSO is more likely to be EAA based without a diagonal in the optical train.