TheSkySearchers

OK, I finally got round to getting a prism for using in either the 102ED for planetary / lunar or the 80ED for solar observing. Apart from the apparent improved contrast and lack of reflections, my main motivation was that my 2" Televue diagonal only has a single locking nut:
This was causing an issue with the binoviewers that clamping on to the 2" nose of the binoviewers (I have an adapter installed on the BV nose to convert it from 1.25" to 2" was never actually that secure and in fact could be slightly moved unless you really clamped down hard and i feel this was most likely resulting in the binoviewers not being completely straight in the focal plane. However, a more serious issue was that when I want the binoviewers angled down for me to sit at comfortably, the downward force of the binoviewers with the angle of the diagonal now caused the binoviewers to be able to rotate in the diagonal... obviously, this is not good!

Therefore, decision was made to change the diagonal. I mulled between the Tak 1.25" diagonal, Baader 1.25 (not in stock anywhere) or this, the Altair Astro 2". All, pretty much around the same by the time extensions / adapters are added in for the 1.25" diagonals.

The TV diagonal is an old(ish) (I believe from 2005?) is in perfect optical condition and works excellently on DSOs however I definitely see an amount of light scatter with some reflection in this diagonal so it will be interesting to see how much the AA prism improves this.

Hopefully should be able to get my hands on the Altair Astro prism diagonal either Wednesday or Thursday - just in time for Jupiter's opposition.

Very nice Dave, have you tested the 102mm to see if a prism will be beneficial?
If not it may add aberrations to the view instead of enhancing.

Congrats Dave! I been using 2" Altair Astro Prism for over a year. Got it shipped from UK. It is a top quality prism and works nicely in all my scopes including SV102ED which is similar to yours.

Lady Fraktor wrote: ↑Mon Sep 19, 2022 5:17 pm Very nice Dave, have you tested the 102mm to see if a prism will be beneficial?
If not it may add aberrations to the view instead of enhancing.

Thanks! I star tested it quite a while ago and going slightly out of focus the first ring exhibits a red(ish) colour. In focus there is absolutely no CA in this scope.

Bigzmey wrote: ↑Mon Sep 19, 2022 5:56 pm Congrats Dave! I been using 2" Altair Astro Prism for over a year. Got it shipped from UK. It is a top quality prism and works nicely in all my scopes including SV102ED which is similar to yours.

Thanks Andrey! Good to know you deem it a top-quality prism - reassuring I've made the correct decision! Amazing they do it at this price compared to the competition...

davesellars wrote: ↑Mon Sep 19, 2022 6:46 pm

Bigzmey wrote: ↑Mon Sep 19, 2022 5:56 pm Congrats Dave! I been using 2" Altair Astro Prism for over a year. Got it shipped from UK. It is a top quality prism and works nicely in all my scopes including SV102ED which is similar to yours.

Thanks Andrey! Good to know you deem it a top-quality prism - reassuring I've made the correct decision! Amazing they do it at this price compared to the competition...

I know, right? I could not find any reviews on forums at that time and took a chance on it. Was impressed with the build quality, similar to Baader ClickLock. Since then I had multiple chances to use it and was able to push my scopes to the limits with it (both limiting star magnitude and resolving limit), so it has my confidence.

Bigzmey wrote: ↑Mon Sep 19, 2022 7:06 pm I know, right? I could not find any reviews on forums at that time and took a chance on it.

I'm a little surprised there aren't many reviews of this nor even with the 2" APM prism diagonal (it looks to be identical with apart from the branding) which now looks to be discontinued by them.

What's the performance of this like in comparison to your Baader Zeiss prism? Have you seen any real difference?

davesellars wrote: ↑Mon Sep 19, 2022 7:21 pm

Bigzmey wrote: ↑Mon Sep 19, 2022 7:06 pm I know, right? I could not find any reviews on forums at that time and took a chance on it.

I'm a little surprised there aren't many reviews of this nor even with the 2" APM prism diagonal (it looks to be identical with apart from the branding) which now looks to be discontinued by them.

What's the performance of this like in comparison to your Baader Zeiss prism? Have you seen any real difference?

It's a bit tricky to do side by side diagonal comparison. I can tell that with both prisms I can push scopes to their limits, so if there are differences they are minor. Stepping from mid level dielectric to quality prisms was quite obvious (considerable performance improvement on planetary, lunar and doubles). Between the prisms nothing jumps in, so I use them interchangeably.

Wow, this thing is solid as a rock (and weighs equally as much).
... Of course, it has come accompanied by clouds (and now rain to boot!).

The worse the weather the better the equipment!

Congrats on the big chunk of quality glass. It works like counterweight for your scope to.

Last night, I took the opportunity to use the new diagonal with the binoviewers to start and the 102ED... On Jupiter - What a difference!!! My initial reaction was "holy cr*p that's sharp...." ... and the seeing was only mediocre... I used both the 18mm BCOs and the 12.5mm orthos (the seeing was not really good enough for the orthos) however absolutely no flare or light scatter seen from the very bright Planet - only a very clean image.

Once I'd had my fill of Jupiter, I turned to M45 with the 25mm SLV which presented very well and clean and then up to M33 which was just about visible (the transparency wasn't great though).

I finished with a star test using the 10mm BCO and now both intra-focal and extra-focal rings are pretty much the same and the first ring colour (previously obvious pink / red was now white. In extra-focal there is a very slight violet tinge at the very edge.

The "click-clock" style mechanism is so much better for using with BVs - A heap more secure and easy to adjust the angle so I could sit down and soak in the view.

I know right? Once you look through a good quality prism the difference is obvious.