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William Optics Binoviewer, and SW 80ED ?

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#1 will1384

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Posted 30 March 2013 - 02:02 AM

Long drawn out story

I wanted a telescope for mostly taking pictures, my girlfriend wanted a telescope just for viewing, and my dad has bad eyes and uses a wheel chair or cane when he can, also wanted to take a few pictures, but mostly viewing, so it was between an 8in sct or an 80mm refractor, I got my way, and got an Sky-Watcher Pro 80ED APO, but with the telescope, the mount, and a few accessories, I was out of money, and was saving up to get a Reducer / Corrector for the 80ed, when the girlfriend spotted a good deal on a William Optics Binoviewer, new with two pair of eyepieces, and now I have binoviewer on order.

What I need to know

What do I need to make the binoviewer work with the 80ED?

I looked threw a lot of forum posts, I found a lot of references to a 1.25 prism diagonal, but the problem is that all the 1.25 prism diagonals I find are made from plastic, I don’t want that, I fear the plastic diagonal breaking under the load, but it seems like only the mirror diagonals come in metal, I have seen other options, high dollar options, costing more than the binoviewer, and I am not going down that road, so what other options are open to me, and unfortunately it needs to be cheap, say around $100 at most.

Here are a few ideas that I think might work.

(1) Get a good metal 1.25 mirror diagonal and use a 2x barlow on it.
(2) Get a plastic 1.25 prism diagonal and stuff its guts into the metal 1.25 mirror diagonal.

#2 johnnyha

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Posted 30 March 2013 - 06:31 AM

You will be better off with a decent quality 1.25" mirror diagonal -the prism will cost a lot and will only get you a couple mm extra in-focus.

#3 Messyone

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Posted 30 March 2013 - 06:47 AM

Put the barlow on the front of the diagonal...the bit that goes into the focuser.

#4 junomike

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Posted 30 March 2013 - 07:08 AM

Put the barlow on the front of the diagonal...the bit that goes into the focuser.



Doing this will cause a magnification factor of 4X (or more) which may or may not be useful depending on the target.

If your Binoviewers doesn't include the "Corrector" as seen here! I'd recommend that as It gives a more useable magnification (approx 2X) as well as corrects for aberrations induced by the Binoviewer Prisms.

Mike

#5 REC

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Posted 30 March 2013 - 07:56 AM

The only way for me to get my 80ED to focus is to screw the 1.6x into the front of the diagonal. I don't think it make it 4x then?

bob

#6 junomike

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Posted 30 March 2013 - 08:16 AM

By placing your 1.6X in front of the Diagonal may not yield 4X but It's probably a lot more than the nominal 1.6X.

You can easily test this out in the daytime using shingle (or siding) on distant houses. When you get the same Image (equal amount with Bino's and single eyepiece) you can then calculate the 1.6X OCS true magnification)
My guess would be somewhere in the 2.5X - 3.2X range.

Mike




#7 will1384

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Posted 30 March 2013 - 10:37 AM

Yep, that Astro-Tech diagonal was one I was looking at, also the William Optics 1.25" Carbon Fibre Dielectric Diagonal, its only about $10 more when you factor in shipping, the binoviewer I have on order does have the 1.6x barlow, and I also have a 1.25 Celestron 2x Barlow that has a detachable barlow element, and that barlow element could be placed on the Diagonal.

I am thinking about saving up and getting the Siebert Optics low profile 1.25 diagonal, as it looks to be $169, but that may be some time as my priority is imaging, and with the "4 - 6 week wait" listed on the Siebert Optics main web page, I am going to get something like the Astro-Tech diagonal as soon as I can, to hold me over until I can save up some more money.

Has anyone tried the Siebert Optics low profile 1.25 diagonal on a telescope like the 80ED, did it work without the barlow, and was it worth the $169 over just using a barlow ?






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