Best diagonal

[LewisM]

Who manufactures the most reliably consistent maximum transmission/least light loss/scatter 2" or 1.25" diagonal?

Are Tak diagonals worth it? TV (I had a 1.25 TV, and it was nice)? AP?


Need the best I can obtain to suit my new Takahashi visual arrival, and I think the Meade I currently have (generic rebranded Chinese) won't give me the best view possible - good, but no cigar :)

Yes, it's pedantic, but...

[Larryp]

I have always used Televue 2" dielectric mirror diagonals-cannot fault them.

[blink138]

i have a 2" takahashi diagonal too lewis if you want to lend it?
pat

[RB]

On my TOA 130 (and all my other scopes) I use a TeleVue 2" Everbrite Diagonal.
Beautiful quality, never needed any other.

:)

[SkyWatch]

If you want the best, then the TV or Tak are probably the way to go. However, I use a GSO dielectric quartz one: the specs (if you can believe such things) give better figures than either TV or Tak (GSO claim 1/15 wave!), and it is very well made: at 1/4 of the cost of the Tak...

- Dean

[brian nordstrom]

:D Lewis there is no shame in owning and using the GSO's , I have one in my SKY90 a GSO 2 inch Quartz type and when I was in Darwin 4 of us did a blind comparisim using 3 telecopes , My sky90 , a np127 TV APO and my 127mm iStar achromat , we set up on a good dry season night and one person shifted the 3 diagonals , My GSO , a TV Everbrite and an AP Maxbrite , all 2 inch between all 3 scopes at random , he kept notes as to which diagonal was in which scope and our comments and to be very honest here ,,,, none of us could see the slightest bit of difference in all three . It sure was fun reading these over a beer later on :D colourful reading .

Objects were , moon , Jupiter , Mars , Alpha Crux triple star system and the eta Carina nebular , all eyepieces were TelVue Naglers , a 22mm ,14mm and 6mm .

There is mystique in owning a top shelf diagonal for sure , but we found that the difference in the field is neglegable at best and highly suggestive with not one diagonal any better or worse than the other 2 , but hey its your money and if you want an AP , TV or Tak ;) diagonal go for it .

I like my GSO Quartz , its very , very good .

Brian.

[PlanetMan]

I would have to concur with Brian regarding the quality of the mirrors in the diagonals. Indeed, from my experience images seemed slightly better in my quartz GSO than an everbrite. However, this was a memory comparison over different nights and I wouldn't bet my house on this.

Now - the real question is what actually makes the TV Everbrite better and why everyone buys them. They are IMO as follows:

1) One piece design - when you have that 1k$ 21mm Ethos or 31T5 terminagler in your diagonal and your EQ mount turns onto a horizontal angle you have complete peace of mind the nose won't twist and down goes the EP. You can try threadlock or glue on GSO diagonals but for 100% peace of mind you can't beat a one piece design.

2) Durability - this is both on the construction of the actual diagonal and coatings on the mirror. Basically, you buy the everbrite and that's it for life.

3) Resale value - TV products tend to hold their value better than virtually any other gear

Having said all of this does not down play the excellent piece of equipment the GSO quartz diagonals represent but merely highlighting the main benefits of the Everbrites.

[LewisM]

Thanks everyone. I'd like to TRY Tak, just to "stay with the team" and see how they are. I know what the TV's are like, having had a 1.25" one.

Will keep looking for a second hand one, or shell out the deniro to Claude.

[LewisM]

Thanks Pat - I might take you up on that gracious offer.

[Don Pensack]

The Vernonscope quartz dielectric ranks right up there.
Also the Astrophysics Max Bright.
These for mirror diagonals.
For prisms, Baader and Zeiss.

[Renato1]

Darned if I can see much by way of difference between my Celestron, Meade, Televue, William Optics, GSO and some no name brand diagonals. Certainly not on DSOs though sometimes, if I try hard, I think I can imagine a slight difference on planets.
Regards,
Renato

[N1]

I agree with all of the above. I have replaced my 1.25" WO diagonal with an Everbrite for different (initial) reasons. The WO is actually pretty good overall, but I had 2 issues with it: vignetting eyepieces (especially the 24 Pan) and a snagging compression ring. Both things I was not prepared to tolerate forever (I did for 2 years) and the Everbrite solved both.

Despite having a greater internal diameter, the Everbrite is smaller than the WO. The recessed area where it connects to the visual back of the refractor is cylindrical not conical, meaning that is is held in place more precisely and securely.

My only complaint about the Everbrite is the thumb screw. It stands out further than on other units and collides with my nose at some observing angles.

In terms of brightness, I can't say I've seen a difference though.

[acropolite]

+1 for the GSO quartz, keep the extra money for your next fad...:P

[AG Hybrid]

Which ever you choose, don't forget to open them up and flock or paint the insides (minus the mirror of course). Pretty much all of them have reflective surfaces on the inside and are reminiscent to glitter balls. Some simple flocking material or black board paint will provide a small improvement to contrast.

[brian nordstrom]

Good advise Planet man , but my GSO Quartz actually has 3 tiny grub screws hidden inside , coming upwards to lock the eyepiece holder so it cant undo , also my sweet TMB 2 inch Dielectric has 3 inside as well but coming in from the sides , hidden under the side plates these are tiny only a about 1.5mm allen key.
I only found these by accident one day , being the consument tinkerer;) .

Brian.

[Octane]

Hey Lewis,

I have a 2" Takahashi diagonal you're welcome to borrow.

I don't know if if will fit your Baby "Q", though. It was designed specifically for the 106N. :)

H

[Kunama]

Personal preference only but after trying the Tak 1.25", GSO 2", Baader 2" and a few others, I decided on the Baader 34mm Zeiss Prism, it is just beautiful and seems to really suit the Fluorite Taks.

[UniPol]

I think I've owned most brands (mirror & prism) over the years and can honestly say that I've really not noticed any appreciable difference in their performance. I currently own TeleVue and Takahashi diagonals mainly because of their build quality, compatability with the same branded eyepieces, telescopes and the expectation that they will perform well and have a good resale value. My Unitron 50 year old plus prism diagonals certainly perform very well to this day.

I have mentioned on this forum in the past that there is really only one way to test if a diagonal is up to the mark at least on an amateur level and that is to just put your eyepiece in the drawtube and just look straight through so to speak, ah la Galileo Galilei style.

[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]

Thanks all.

I have committed to buy Tony's 1.25" Tak prism diagonal, so will give that a crack for a while.

H, I may come down and tak ..errr. TAKE you up on that kind offer (saves any postage issues with Pat's). The FSQ85 has both the 2" and 1.25" visual backs, so shouldn't be an issue.

I tried the Meade through the FSQ with the Tak 2" back, and I can say that's a VERY well designed and EXTREMELLY solid clamping ring! No movement whatsoever. I have had diagonals come loose in GSO, SW and Vixen compression rings, but no way on this one. The 1.25" "click-lock esque" of Tak's is just plain solid as a rock too.

I hated the Vixen compression ring so much I put a Baader Clicklock with Vixen adapter on it. Like their adverts show, I could pick the OTA via the diagonal if i were so stupid to try it :)

[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.

[LewisM]

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

Not Zeiss, but not Zeiss price either :)

[SkyWatch]

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.

[SkyWatch]

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]

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.