Best diagonal

[gbeal]

I disliked the Tak (1.25") clamping mechanism, felt it never really tightened, unless you put a lot of torque into it. Didn't gel with it at all.
The favourite is my Zeiss 2", it came with my ED80/840, but it comes at a cost, financially and weight wise. It's huge.
Gary

[Peter Ward]

Dealer Hat off for a bit: with a very good friend who I'd describe as being a very experienced planetary viewing nutter, we tested a number of 2" diagonals, Taka, TeleVue, WO quartz di-electric and AP's MaxBright di-electric.

The test was simple enough, we used an AP155 at about 1000x magnification
on a bright star, and compared the images with and without the diagonals.

The AP was the only diagonal that imparted absolutely no distortions to the image.

[Steffen]

Some eyepieces' undercut can interfere with the Tak 1.25" prism's twist clamp. If that happens lifting the eyepiece out a few mm will solve this, and the twist lock will hold the eyepiece firmly without the need to apply much force.

In spite of this I prefer the Tak prism to the very good Intes (or any other) mirror diagonal for double-stars and planets, there is visibly less scatter and more clarity at high magnification in high contrast scenes (like when splitting very uneven doubles). That's in my f/12 Maksutov, of course.

Cheers
Steffen.

[sharpiel]

That's quite an interesting comparison. Speaks very highly for quality prism diagonals over even quality dielectric mirror diagonals. Even more importantly on planetary detail and contrast.

Thanks for the link.

Originally Posted by brunono2

Lewis

BEFORE you buy a diagonal I suggest you read the attached cloudy nights diagonals Review- Baader T2+ 2 inch prism feature highly

Cheers

Bruno

[LewisM]

Yes, the article was enough to persuade me to purchase a Tak prism diagonal.

Not Zeiss, but not Zeiss price either

[SkyWatch (Dean)]

You should be very happy with it: I was thinking you were looking for a 2" when I suggested the GSO, but I also have a Tak 1 1/4 prism and it is very good- plus for a Tak it is very reasonably priced!

All the best,

Dean

[sharpiel]

The thing that stood out most to me was the implication that the diagonal (whatever the variety) is an extra distorting element in the light path between our expensive optics and eyes; and that the best image will be obtained by not using one at all...even high end ones. A bit awkward for discerning visual observers (read planetary) with high end refractors and old sore backs.

Originally Posted by sharpiel

That's quite an interesting comparison. Speaks very highly for quality prism diagonals over even quality dielectric mirror diagonals. Even more importantly on planetary detail and contrast.

Thanks for the link.

[SkyWatch (Dean)]

Originally Posted by sharpiel

The thing that stood out most to me was the implication that the diagonal (whatever the variety) is an extra distorting element in the light path between our expensive optics and eyes; and that the best image will be obtained by not using one at all...even high end ones. A bit awkward for discerning visual observers (read planetary) with high end refractors and old sore backs.

This is probably why it is very popular in Japan to view straight through, no diagonal.
I know the problem with the back!

[LewisM]

The Tak 1.25" prism diagonal arrived yesterday, and I am VERY impressed. Quite a lot better image than the 99% reflectivity (claimed) of the generic manufacture rebranded as Meade 2" diagonal.

[The Mekon (John Briggs)]

Another option not mentioned yet is the University Optics 2" prism. I have no idea who makes them, but can attest having had one for 20 years that they are of excellent quality. At twice the price of their mirror diagonal they should be.

[LewisM]

The first telescope I ever had -a Toya made Tasco 50mm refractor - used a prism. I still have the diagonal here too - in all it's 0.965" goodness

I have used and still own mirror diagonals and dielectric ones, and I am not sure they show the same fidelity - when I looked through the Tak first yesterday, my mind was playing tricks on me and I honestly thought I was looking straight through a tube, not initially realising I was looking at a perpendicular image - they are astonishingly clear and show no internal reflections I can see (whereas the dielectric I have scatters some light on the walls of the diagonal etc.)

May get a Baader-Zeiss one of these days, but for now, in my limited visual role, I will stick with the Tak.