W.O. Durabright Diagonal ??????

[PlanetMan]

I think everyone agrees that Quartz diagonals are very good but what I am very keen to know about is what is the idea or concept behind WO producing a 15mm thick non-quartz dielectric mirror diagonal. If there isn't any advantage or specific angle to it why would they bother making such a diagonal? Consequently, there has to be some sort of specific reason for the creation of the DURABRIGHT and I would be very interested to find out if anyone might know - It is not actually a cheap diagonal either - originally the durabright was the same price as the WO Quartz

[robz (Robert)]

Originally Posted by UniPol

Geez guys, only one disembowelling per day from now on if you don't mind . I might as well dismember the Meade Series 5000 and Bintel Quartz but definitely not the Tak diagonals over the following days just to satisfy those curious IISpacers.

Firstly, I took both side plates off the Dura-Bright and I would say that WO have used a retaining compound to lock the 2" slip in barrel or tightened it up so hard it can't be removed to attach the SCT fitting unlike the Quartz version.

Secondly, I have attached an image of the TV Everbrite, the mirror is around 10mm thick (a mm or so thicker than the WO quartz). It is set into the base plate as shown and has a fibre shim to hold it just in place.

* I'm going to ignore the comment about " float glass ", indeed!

Cheers everybody

We appreciate your efforts Steve...............I was only playing around with the float glass comment

Rob.

[UniPol]

Originally Posted by PlanetMan

I think everyone agrees that Quartz diagonals are very good but what I am very keen to know about is what is the idea or concept behind WO producing a 15mm thick non-quartz dielectric mirror diagonal. If there isn't any advantage or specific angle to it why would they bother making such a diagonal? Consequently, there has to be some sort of specific reason for the creation of the DURABRIGHT and I would be very interested to find out if anyone might know - It is not actually a cheap diagonal either - originally the durabright was the same price as the WO Quartz

Well, I tend to think it may be a marketing exercise. WO will slowly sell off their Quartz stocks and the Dura-Bright will reign supreme.

I have attached a couple of pics again, the first is Bintel's and the second, Meade's Series 5000. The Meade is very well made, in fact you may notice that the mirror is housed in a metal pressing which is attached to the body with four screws (a pair either side). Both mirrors are 99 percent reflective and around 10mm thick.

Something which hasn't been mentioned before is the fact that the light path passing through the diagonal must be reflected at 90 degrees. Sounds obvious but some high end manufacturers such as Takahashi, TeleVue, Astro-Physics etc. go to great pains to obtain this and maintain this accuracy over time.

The next instalment in the series will be a 2" SkyWatcher and 2" Celestron diagonal.


* Come to think of it Rob, float glass has been used to make some pretty decent newtonian mirrors in the past, so why not mirror diagonals .

[robz (Robert)]

Thanks again for your effort Steve.

The Bintel is interesting isn't it?..............they have left the glass square with only the edges cut off at 45 degrees..........clever, cost effective.

As you mentioned that the G.S.O (BINTEL) diagonals are up there with the best of them, I'd say after my experience in using the dielectric quartz version, I would whole heartedly agree..........excellent value for money.