asaint
Carpal Tunnel
Reged: 04/25/03
Posts: 2021
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Hyperion 24mm Wide Field
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lynntx
sage
Reged: 03/25/04
Posts: 283
Loc: North Texas, USA
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Nice review,
I may have to go for one of these. I have the 8mm and 17mm and I am pretty pleased with these budget widefields. I kind of like the light weight and small barrel versatility for use with some smaller scopes.
A bonus application is that my ST80 makes a decent "spotting" scope with a 45* diagonal and these e/p's.
Lynn
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Texas, USA
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Orion ST80
127mm F8 Burgess Refractor
8" F6 Dob
8X21, 8X30, 8X42, 7X50, 15X70 Binoculars
(Psalm 19:1)
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WadeVC
Carpal Tunnel
Reged: 12/02/05
Posts: 2799
Loc: Lodi, California,
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Very nice review. Quite comprehensive, objective and written in a manner in which observers of all levels can understand.
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Orion XTi10 f/4.7
Orion XTi8 f/5.9
Meade NGC 70mm f/10
Orion UltraView 10x50 Wide-Angle Binoculars
My Sketch Gallery
My Astronomy Blog
A wise man can see more from the bottom of a well than a fool can from a mountain top.
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kfred
Carpal Tunnel
Reged: 11/11/03
Posts: 2005
Loc: Dayton, Ohio
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Great review. I'm planning on getting one for x-mas.
Fred
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River Cam - Cambridge England
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longfocus
sage
Reged: 02/03/07
Posts: 378
Loc: Sunshine Capital of Canada
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I've used most of the Hyperions and they don't compare to the Panoptics for example in terms of correction, glass, and coatings.
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<.5A PST
4" APO refractor
Premium TeleVue eyepieces
Waiting for my 17.5" reflector!
All achromats sold
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Starman1
Vendor - Scope City
Reged: 06/24/03
Posts: 10960
Loc: Los Angeles
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As knowledgeable readers will know, one cannot simultaneously correct for rectilinear distortion (pincushion or barrel) and angular magnification distortion.
The review says (incorrectly, I believe) that there is no rectilinear distorion present in the eyepiece. What he should have said is that there is no "objectionable" distortion. For if the eyepiece literally had no rectilinear distortion, it would have had lots of angular magnification distortion, which would have made itself noticeable at the edge as a "stretching" and "defocusing" of the image. This wasn't noted, so the effect must be small.
I suspect the eyepiece has pincushion distortion, which would not have been visible in a starfield, but would have been visible on daylight targets. This seems to be an inevitable solution to current widefield designs. However, with this wide a field, it could be held to tolerable levels by admitting a slight amount of AMD at the edge (which might have been one of the edge problems commented on).
In essence, the eyepiece represents a reasonable compromise for someone looking for a less expensive widefield (I've heard of it being for sale as low as $100 when it was introduced) and, at long focal ratios, may not be a compromise at all.
Commendable detail in the review.
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Don Pensack
12.5" Truss Dob, 5" Maksutov
Sustaining Lifetime IDA member, TeleVue junkie
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BillP
Carpal Tunnel
Reged: 11/26/06
Posts: 2244
Loc: Vienna, VA
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Hello Starman 
Actually I did test it on daylight target...perhaps that line got edited out. Anyway, I moved it to a windowframe and put the edge of the frame at edge of the field and there was no observable curvature to the staight wood frame in my 10" Dob. So no observable rectilinear distortion. Is that "zero" well maybe some was there but from an observation standpoint it was zero on the window frame, and certainly nothing detectable in my scope on star fields or Luna. Of course, as I understand it, the designers can trade off other distortions, which may be why astigmatism and field curvature are present.
-Bill
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250mm f/4.7 Orion XT10i Dobsonian
102mm f/8.0 Tak TSA Super-APO
66mm f/5.9 WO ZenithStar SD APO
40mm f/10 Coronado P.S.T.
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sixela
Postmaster
Reged: 12/23/04
Posts: 9499
Loc: Boechout, Belgium
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Quote:
For if the eyepiece literally had no rectilinear distortion, it would have had lots of angular magnification distortion,
Not "lots". It's only a 68° AFOV eyepiece. atan(34/57.3) is only 10% off 34/57.3; it's not that bad.
And yes, there is very little rectilinear distortion in Hyperions - some even have barrel distortion (which means they have even more angular magnification distortion).
Quote:
which would have made itself noticeable at the edge as a "stretching" and "defocusing" of the image.
Angular magnification distortion doesn't defocus the image (all it does as far as you can see is fail to preserve local angles at the edge). Field curvature does, though, and there certainly is some as well.
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400mm f/4.46 David Lukehurst truss Dobsonian on Tom Osypowski equatorial platform
Orion Starblast (114mm f/4 reflector, Alt/Az)
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Starman1
Vendor - Scope City
Reged: 06/24/03
Posts: 10960
Loc: Los Angeles
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Yes, "defocusing" wasn't the right word. "lack of preservation of angular arrangement of the image", which would only be important with extended images.
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Don Pensack
12.5" Truss Dob, 5" Maksutov
Sustaining Lifetime IDA member, TeleVue junkie
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longfocus
sage
Reged: 02/03/07
Posts: 378
Loc: Sunshine Capital of Canada
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Quote:
Hello Starman
Actually I did test it on daylight target...perhaps that line got edited out. Anyway, I moved it to a windowframe and put the edge of the frame at edge of the field and there was no observable curvature to the staight wood frame in my 10" Dob. So no observable rectilinear distortion. Is that "zero" well maybe some was there but from an observation standpoint it was zero on the window frame, and certainly nothing detectable in my scope on star fields or Luna. Of course, as I understand it, the designers can trade off other distortions, which may be why astigmatism and field curvature are present.
-Bill
Perhaps we might use the word eyepiece 'abberations' rather than eyepiece 'distortions'.
Although it is not a 24mm Panoptic, it is certainly not the worst eyepiece I have used, but certainly not anywhere near the best in its class I have sampled either. I believe that an eyepiece is as an important investment as a telescope and should be approached in that manner.
When I could not afford superb widefield eyepieces, I used some well made "Ultrascopics" until money was not going to be an issue. Better to have a well-corrected modest field than a mediocre widefield in my honest, humble opinion.
Of course, there is never going to be a perfect eyepiece, no matter what. Some get pretty close, and for those oculars, there are no substitutes.
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<.5A PST
4" APO refractor
Premium TeleVue eyepieces
Waiting for my 17.5" reflector!
All achromats sold
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ckwastro
professor emeritus
Reged: 11/23/05
Posts: 733
Loc: AZ
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Bill, thanks for the great review! I've been thinking of trying a pair of these for my binoviewer rather than dropping a ton of cash on the 24 Pans. Sounds like they will be a very respectable alternative.
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Kerry
- 92mm AP Stowaway (f/7 version, uh...actually f/6.57
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- Takahashi Mewlon 210
- Giro 3 Twin View
- 10x42 Audubon Equinox
- Bogen 3221 tripod / 3047 3-Way Head
- Denk Std BV
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Alan K
sage
Reged: 09/21/05
Posts: 239
Loc: Atlanta, USA
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Great write up Bill. Is there a difference in the top lens size between the 24mm and the other hyperions? The picture makes it appear smaller, maybe just an "optical" illusion?
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Meade LX90 (8" f/10 SCT), Orion StarBlast (4.5" f/4 Reflector)
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imeridian
scholastic sledgehammer
Reged: 08/22/07
Posts: 893
Loc: South Central PA
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Here is a photo that shows the difference in eye lens size fairly well.
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Alan K
sage
Reged: 09/21/05
Posts: 239
Loc: Atlanta, USA
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I see, great picture. Thanks imeridian. There is quite a difference in design. Interesting.
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Meade LX90 (8" f/10 SCT), Orion StarBlast (4.5" f/4 Reflector)
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