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William Optics 2" DIELECTRIC Diagonal

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#1 Gordo

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Posted 22 March 2005 - 11:26 PM

I’m thinking of upgrading my 1.25 televue everbrite diagonal to a William Optics 2" DIELECTRIC Diagonal. The scope is a 9.25 celestron xlt.
Anyone used this diagonal? Thoughts?
Thanks

#2 PMB

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Posted 23 March 2005 - 07:24 AM

Although the WO is a nice diagonal I dont see where you'd gain much unless you have 2" EP's you're wanting to use, or plan on buying to use. I thought "Everbrite" WAS the dielectric coating model for TV. I've used both.

#3 celestial_search

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Posted 23 March 2005 - 11:08 AM

I use the W.O. 2" diagonal (non-dielectric). Main difference is the dielctric has 2% (supposedly) more reflectivity. Although reflectivity is not the only consideration when getting a diagonal, they are well-built. They come with a compression ring and 1.25" adaptor (also with compression ring). I noticed a difference using it compared to my stock Celestron diagonal. I only use 1.25" EPs as of now (may get a couple of 2" at some point).

#4 Starman1

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Posted 23 March 2005 - 11:52 AM

Move to 2"? Good move. You'll be able to use all eyepieces and you'll finally be able to see the entire field of view the scope can offer (not possible in 1-1/4").
Move to Dielectric? Better move. The coatings don't deteriorate appreciably with time, meaning that 10 years from now you'll still be enjoying the full brightness of the images (though your telescope may need recoating). Off-axis light scatter is less with the dielectric coatings, and they are harder (less likely to scratch when cleaning).
The 2" diagonal is more desirable for one more, arcane, reason. Roland Christen has pointed out that these coatings tend to become more irregular near the very edge of the mirror. 2" is enough oversized (given the size of the opening in the back of your scope) that the edges of the mirror in the star diagonal will likely not be used, producing even better images than a 1-1/4" diagonal.
You have a few choices: William Optics, TeleVue, and AstroPhysics. The WO is the least expensive one of the bunch. Recommended.

#5 RGM

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Posted 23 March 2005 - 12:15 PM

Everything Don said. I use the standard WO 2" on all scopes. Provides a more stable platform for heavy EPs and Binoviewers. I am thinking about getting the dielectric for the advantages that Don mentioned.

#6 Adolfojose

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Posted 23 March 2005 - 02:00 PM

I have recently changed my TV 11/4" Everbrite for a WO 2" Dielectric, and am very happy with the change. Really, best plattform for binoviewer and heavy eyepieces.

#7 Guest_**DONOTDELETE**_*

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Posted 24 March 2005 - 12:29 AM

Gordo

Ask yourself also whether you want the WO SCT or refractor version of the diagonal. The refractor version requires a 2" visual back, but is easier to position for comfortable viewing and is useable in non-SCTs.

-Gavin

#8 Starman1

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Posted 24 March 2005 - 01:33 AM

Gordo

Ask yourself also whether you want the WO SCT or refractor version of the diagonal. The refractor version requires a 2" visual back, but is easier to position for comfortable viewing and is useable in non-SCTs.

-Gavin

And has a larger aperture for less vignetting.

#9 Gordo

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Posted 24 March 2005 - 08:02 AM

Thanks everybody for the input, I will probably pick one up this week. A WO 2" dielectric diagonal and a 2" visual back.

Thanks again

#10 jake47

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Posted 24 March 2005 - 10:50 AM

I don't want to get accused of working for a company I recommend again, but ... :grin:

If you are looking at 2" dielectric diagonals, You might also look at the Stellarvue model. I have a regular WO in my SCT and the Stellarvue dielectric in my refractor. I was really proud of my WO when I got it -- still using it. I was even more impressed with the SV unit.

My WO is SCT specific, but I have been thinking of getting a 2" back so that I can compare the two in my NS11.

Just another two cents worth. Thanks

#11 gazerjim

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Posted 25 March 2005 - 02:34 AM

I've heard that dielectric coatings also serve as NIR filters for ccd imaging. True?

#12 Guest_**DONOTDELETE**_*

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Posted 25 March 2005 - 11:51 PM

If you can, get a visual back with a compression ring instead of set screws.

-Gavin

#13 Gordo

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Posted 26 March 2005 - 02:59 AM

I will, I seem to lose the screws all the time
Thanks

#14 John_Gillies

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Posted 27 March 2005 - 03:19 PM

Here's the William Optics diagonal I hope to have soon. It's a WO diagonal with a Denkmeier dual arm Power X Switch. Can be gotten for single eyepieces or binoviewers. They cost a little more money, but saves on eye pieces.

Attached Thumbnails

  • 387481-S1 jpg.JPG


#15 Starman1

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Posted 27 March 2005 - 06:52 PM

John,
Is that available with a dielectric-coated mirror?

#16 Gordo

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Posted 27 March 2005 - 08:16 PM

I looked at it, but it's no yet available in dielectric coating.

#17 Tim

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Posted 27 March 2005 - 08:26 PM

Here's a response that I got when I asked a similar question
from another post

I have moved parts of previous post here for your information.

On a C9.25, it's important to select a *short* 2" diagonal, though, especially if you might also want at some point to install a focuser on the SCT back - there's not a lot of back focus on the C9.25. If you're sure you'll never want one, of course, there are diagonals with SCT threads.

heres another choice to consider

ASTRO-PHYSICS 2" MAXBRIGHT DIAGONAL

"The elements are oversized and thick enough so that the end result is a highly accurate reflective surface over the clear aperture that is actually used with any kind of telescope.

http://www.company7....ns/apmaxbt.html

it's the diagonal that I'll be buying for my C9.25

:jump:

#18 John_Gillies

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Posted 27 March 2005 - 08:56 PM

I've been talking to Russ and Bill at Denkmeier and they were awaiting the arival of the dielectric diagonals to add the power x switch to. They plan to have them available at NEAF. They come with a choice of SCT visual back adapters. One is called the "Shorty to be used with all SCT's of 9.25" aperture or smaller. As well the diagonals come with a choice of short or regular telescope-side tubes. For the 9.25" you would need the short tube/short visual back model. Exact magnifications depend on whether you order the #S1 for single eyepieces or the #S2 for binoviewers. Last year at Starfest, I was able to try the #S1 prototype in my 8" LX10 (pictured here) and it worked great. Three power levels with one eyepiece. They intend to showcase all the models at NEAF as well as sell them.

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  • 387710-SCT Diagonal Power X Switch 1 2 3.jpg


#19 Tim

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Posted 28 March 2005 - 12:16 AM

the power x switch would be a nice option glad to see they are making a short version maybe I will have to re think my decision.

I wonder what the price will be and when they will be available in Toronto

#20 John_Gillies

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Posted 28 March 2005 - 06:51 AM

Hi Tim,

I can even help with that! I'm not sure if they will be sold by Denkmeier dealers yet, but they are available directly from Denkmeier.

This is from Denkmeier:
$389 + $10 S/H in USA. $35 S/H for foreign orders Code# S1-Short or Code# S1-REG. Includes: telescope-side Power x Switch, 1.25” adapter, SCT Shorty or Regular Visual Back Adapter, (Specify by Code #) (Add $120 for 99.4% reflective dielectric coating)

Thats for the #S1 & #S2, and of course that's US dollars

#21 Tim

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Posted 28 March 2005 - 08:32 PM

Hi John,

What are the different powers available on the switch?

Why cant you use the power switch with your eyepieces and still be able to use it with a binoviewer or can you? :question:

#22 John_Gillies

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Posted 28 March 2005 - 10:47 PM

In the #S1 for SCTs(using single eyepieces) the power levels are: .66X (reduction) - Reducer arm "in", 1X - both arms out, 2X - Multiplier arm "in". On the #S1, the power x switch is on the telescope side of the diagonal. When using binoviewers in the #S1, high power mode exceeds maximum magnification recommendations. Focal reduction mode is non-functional. Only the normal power arms in "out" setting is operational.

In the #S2 for SCTs (using binoviewers) the power levels are: .59X (reduction) - Reducer arm "in". 1.1X - both arms out, 1.7X - Multiplier arm "in". On the #S2, the power X switch is on the eyepiece side of the diagonal. When using single eyepieces in the #S2 the power levels are: .83X - .66X with reducer arm in (moving the eyepiece outward from the diagonal increases reduction factor), 1X - both arms out, 1.5X - 2X with multiplier arm in (moving the eyepiece outward from the diagonal increases magnification factor).

Whew!!! If you understood all that, and I hope I typed it right, The #S1 is optimized for single eyepiece use, and the #S2 is optimized for binoviewer use (this is the puppy I want in dielectric version).

#23 John_Gillies

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Posted 30 March 2005 - 11:12 AM

Look for me at NEAF! Russ and Bill at Denkmeier Optical figured I shoot my mouth off so much about their products, why not invite me to help them out in their booth being that I was attending anyway. I've already got the two-day kitchen pass…so why not? If any of you CNr's are coming, please look me up at the Denkmeier booth. It's always great to meet the folks I've been kibutzin' with in person. I'll be the guy that looks like Calvin!

#24 jrcrilly

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Posted 30 March 2005 - 11:22 AM

Look for me at NEAF! Russ and Bill at Denkmeier Optical figured I shoot my mouth off so much about their products, why not invite me to help them out in their booth being that I was attending anyway.


Cool - I always visit the Denk booth anyway.

If anyone's looking for me there I'll probably be hanging around with the gang from Backyard Observatories. My new Dob will be somewhere around also; I don't think Teeter will have a booth this year so I dunno where it'll be.

#25 John_Gillies

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Posted 30 March 2005 - 11:29 AM

See you there John! You're the wise looking white-haired dude right? I'll keep an eye out for you!


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