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2" star diagonal


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Sorry, just realized that came across as a rather facetious answer - wasn't intended that way.

The point is that a diagonal is just a mirror, so by itself it doesn't give wider views. However, the larger mirror can fully illuminate 2" eyepieces which can give wider fields of view than are possible in the 1.25" format.

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The point is that a diagonal is just a mirror, so by itself it doesn't give wider views. However, the larger mirror can fully illuminate 2" eyepieces which can give wider fields of view than are possible in the 1.25" format.

Indeed. But the downside of a larger diagonal (as well as expense) is that the optical path is longer, i.e. you have to adjust the focus further in to get focus. Do check that you have sufficient inward travel before spending lots of money. SCTs and Maks will be OK, so will premium refractors, but cheap refractors may not achieve focus with a 2" diagonal.

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I have the WO 2" Dielectric on my SCT, and it does give wonderful wide angle views with my Paragon and Nagler EPs, but I did not go for the SCT-version. Rather, I got a 2" visual back for my C8 (from Baader) and stuck a normal diagonal in it. This has the advantage that I can quickly interchange it with my Vixen flip mirror, and I can use it in any scope with a 2" barrel.

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Stardust in the TAL user group has had problems getting a TAL100RS to come to focus with some EPs using a Williams diagonal. I havent seen that problem with my Revelation 2" when it has various 2" EPs in it BUT focus is pretty close in with it when using a 38mm Panaview. I could well believe that a diagonal that was slightly longer may run into problems with some eyepieces.

I think you;d need to know the ansswer from someone who has dont it and got the T Shirt - FLO as ever will be your best port of call on this I suspect.

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its intended for my evostar, which im guessing isnt classed as a cheap end scope? Anyone any experience of this type of scope and 2" diagonal?

I've used a 2" diagonal on Evostar 120 and 150 refractors and, while they do swallow up some in focus, I was still able to get all my eyepieces to focus. The ones that needed the most inward focusser movement (and therefore the ones that came closest to NOT coming to focus) were classic "volcano top" orthoscopics.

Speers-Waler eyepieces also need a lot of inward focus I believe.

I don't think the WO 2" diagonal needs any more inward focus than any other 2" diagonal.

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