Diagonal dilemma

[+Stu]

Hi folks. Reading a few observing reports and there's a lot of pictures of different diagonals, prisms etc...

I think at some point I'll be going down a Mak/SCT route for a visual scope (and maybe imaging, depends on the scope). Assuming I pick up a scope with a stock diagonal, is there a particular type I could be looking to upgrade to with those types of OTAs? 

* I have a 2" TS Optics dielectric one but the scopes I've been eyeing up seem to have 1.25" fittings. 

[Nightspore]

 

I tend to use these Baader prisms with my Mak's & SCT. Possibly as prisms don't produce much (if any) CA with long focal lengths. The one below is a Baader 'Zeiss' Amici, although I'm guessing it has never seen the inside of a Zeiss factory. I have a Baader BBHS prism, but I principally use it on my ED80 Evostar. The bog-standard Baader prism with the helical is very good value IMO.

 

[+Stu]

Cool, I'll check them out 👍

Is prism just Baader terminology or a different design to a mirror?

[tuckstar]

The Baader zeiss amici prism is made by baader to the zeiss specifications. So, no it won't ever have seen a zeiss factory. Works lovely with my zeiss scope though.

 

A prism is just that, a glass prism instead of a mirror. My amici prism in my refractor gives me a correct image where as a mirror diagonal would give a flipped view. 

I like the view when looking at the moon as it matches my luna atlas, but, you can get a slight line on brighter objects with the prism due to it being essentially two prisms stuck together but hardly noticeable with the baader zeiss amici I have.

 

And of course the prism will be more expensive than a mirror!

 

Its horses for courses again I'm afraid.

 

 

[Nightspore]

43 minutes ago, Stu said:

Cool, I'll check them out 👍

Is prism just Baader terminology or a different design to a mirror?

 

As Tuckstar said, a prism is glass instead of a mirror. Conventional prisms act just like mirrors in most respects (mirror reversed image). There is some debate about whether mirrors or prisms are better. Bill Paolini did the most intense and famous review: PDF

 

 

This is my (slightly borked) WO Amici 'roof' prism. Personally, I've fallen in love with my Baader BBHS mirror diagonal.

 

[Nightspore]

35 minutes ago, tuckstar said:

The Baader zeiss amici prism is made by baader to the zeiss specifications. So, no it won't ever have seen a zeiss factory. Works lovely with my zeiss scope though.

 

A prism is just that, a glass prism instead of a mirror. My amici prism in my refractor gives me a correct image where as a mirror diagonal would give a flipped view. 

I like the view when looking at the moon as it matches my luna atlas, but, you can get a slight line on brighter objects with the prism due to it being essentially two prisms stuck together but hardly noticeable with the baader zeiss amici I have.

 

And of course the prism will be more expensive than a mirror!

 

Its horses for courses again I'm afraid.

 

 

 

Plus, prisms are usually heavier, especially 2" diagonals.

 

 

This Baader Maxbright 2" mirror works well on most of my mounts. 2" prisms are a different thing altogether. The 60EDF is rear heavy, 2" prisms have serious balance issues. I read somewhere that Baader Amici prisms are BBHS coated but Baader doesn't advertise this fact, Baader have a variety of stories about this, as usual.

Edited November 24, 2023 by Nightspore

[+Stu]

Plenty to think about. I'll definitely take the weight into consideration. Should've held on to my 1.25" dielectric but I sold it with my Bresser refractor.