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Ed Kessler
professor emeritus
Reged: 05/17/06
Posts: 749
Loc: Millersburg, PA
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Dan Mounsey mentions in his review of 4" apos over in the Refractor Forum that his favorite diagonals are the Vernonscope and Baader prisms.
That has me wondering if anyone has ever done a diagonal review, or shootout?
I know this is the eyepiece forum but you guys generally tend to do these kinds of comparisons so I thought I'd ask the question here. Of course, diagonal performance directly relates to how well we see things through our eyepieces.
Clear Skies,
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Ed Kessler
sic itur ad astra (Just to look profound!)
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Skywatchr
Carpal Tunnel
Reged: 06/03/06
Posts: 1585
Loc: North-Central Pa.
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That's a good question. The effect of a diagonal on the performance is very important. Like the secondary mirror on a reflector, it directly translates to the eyepiece and overall performance. But who owns 30+ different diagonals to "shoot-out"? 
Jeff
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18" F/5 Home-Built Dob. with Mike Dudley Mirror
Highly Modified Meade DS-16 in Roll Off Roof
6" F/15 Brass w/ D&G Lens on DS-16 Mount
DS-10 10" F/4.5 Newtonian
LXD650, LX200 Classic
Orange Tube C11
DayStar 0.45 with multiple ERFs
Vixen ED80sf
10" LX200 GPS SMT
11x80 Meade, 20x80 Celestron binocs (Japan Made).
Lots of Naglers and 8mm and 13mm Ethos.
Gadgets and parts everywhere.
And a Wife that loves it as much as me!
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Ed Kessler
professor emeritus
Reged: 05/17/06
Posts: 749
Loc: Millersburg, PA
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Quote:
That's a good question. The effect of a diagonal on the performance is very important. Like the secondary mirror on a reflector, it directly translates to the eyepiece and overall performance. But who owns 30+ different diagonals to "shoot-out"? Jeff
Hi Jeff,
Well some of these folks own or have tested just about every barlow and/or eyepiece that has ever been available. Surely, someone has done some diagonal comparisons.
I have three TV dielectrics and one Astro-Tech dielectric. When the skies finally clear around here  I'm going to compare the two.
I really like Vernonscope products and I'd like to try out one of their prism diagonals, but the cost makes that an expensive experiment.
Clear Skies,
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Ed Kessler
sic itur ad astra (Just to look profound!)
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Dylan Gladstone
scholastic sledgehammer
Reged: 08/05/07
Posts: 955
Loc: Connecticut, USA
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I could compare the stock Orion diagonal that came with my scope to an Astro-Tech dielectric if anyone's interested...
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Orion SkyView Pro 127mm Maksutov
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Stephen65
scholastic sledgehammer
Reged: 04/14/07
Posts: 934
Loc: Melbourne, Australia
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I own and have compared the WO, TV and AP 2" dielectrics. Optically they are indistinguishable, but for build quality and design I like the AP best.
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Megrez 90
FLT 132
Mewlon 250
Lots of XWs, an Ethos, Supermonos and some other EPs
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GeorgeDuke
Pooh-Bah
Reged: 04/24/03
Posts: 1175
Loc: PARADISE! (So.Florida)
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I did a comparison yesterday between a WO dielectric 2" diagonal and a new Orion 2" prism diagonal in a Stellarvue SV102ED2.
I was using the Hyperion eyepieces and wanted to test the CA difference between mirror and prism.
There was no apparent difference in the sharpness but the image was brighter with the mirror.
I was viewing transformers and insulators on a power pole about half a mile away and using the Hyperion 8mm eyepiece.
With the mirror I saw a slight red fringe and with the Prism the red fringe was replaced by a slight blue fringe.
In both cases the color was so slight that I used the fine tuning rings to bring the eyepiece down to 4.3mm or 41X/inch of aperture. That made the CA easier to detect.
The Hyperion fine tuning rings use the same thread size as 2" filters so I inserted the WO MV1 filter between the FTR and the barlow element. This brought the eyepiece down to about 3.5mm and about 50x/inch. The blue fringe was gone and to my eye there was virtually no CA visible.
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George
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LX200GPS 203mm f10
StellarVue SV102ED2 Feathertouch Ser#0018
Celestron 130mm f15.4 Mak
LXD75 GOTO with Orion 16" pier extension
Desert Sky DSV1 dual head ALT-AZ mount
Baader Hyperion 8mm ,13mm, 21mm and 8-24mm Zoom + FTRs
2" GSO ED barlow, Orion 2" Prism Diag. 2" WO Dielectric
Chinese Scopes, Chinese Eyepieces, Chinese Wife, Love them all!
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Snaproll
Post Laureate
Reged: 02/20/04
Posts: 3492
Loc: Wisconsin
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One thing I would toss into the mix is the Denkmeier switch diagonal. Actually it's a WO diagonal modified with a power and filter switch. I love the thing. I can't really compare it to other high quality diagonals since all my previous ones were the stock bottom feeder variety, but... having the power and filter switch options on the dielectric WO makes life so much more fun. Switching between three magnifications and only having to refocus, or swapping in or out two filters (usually a UHC and LP filter) or no filter with a flick of the finger makes life so nice. No fumbling with eyepieces in the dark, no having to pull the diagonal or eyepieces trying to screw filters. I often observe the whole night without changing any hardware. The things are pretty pricy, but rather than buying a battery of good eyepieces I have five and because of the power switch they act like 12. Two D21's, two D14's (for a Denk II) and an Ethos 13 for mono viewing. Pretty much satisfies any kind of viewing I want to do thanks to the switch diagonal.
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-Jim-
Happiness is a clear sky and a Denk II
old AP images and some new C14 Hyperstar images
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