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Bill Fischer
super member
Reged: 11/13/08
Posts: 162
Loc: Magnolia, TX and South America
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Has anyone used the the 31mm Hyperion in an OTA with about an f6.3 ratio? I a saw the CN report on the 36mm, if the 31 is as good I would try one. It will be for my 8"SCT using a Celestron FR. My Orion 38mm Q70 seemed OK at f10 but with the FR attached I can notice it's faults. I want to leave the FR attached that is why I am looking for a better EP.
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Nexstar 8 GPS w/Clestron FR/FF
Telrad
TV Pan 35mm
WO UWAN 16mm
TV 11mm, 8mm
Meade 2x Telenegative
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hfjacinto
Almost got me
Reged: 01/12/09
Posts: 2069
Loc: Union,NJ
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I have both the 36 MM and the 31 MM and IMO the 31MM is better on faster scopes. The issue is that a 2" with such wide field of views will show the COMA of the scope. The 36MM on my F5 is great for 75% and the last 25% shows the coma of the scope. The 31MM is better on the 25%. I would believe that the 31MM will work well on your f6., My question is why are using a FR on F10 scope? With the 31MM and 36MM they will show almost the largest FOV that can be seem in your scope (a pentax 40MM, Panoptic 41MM and 55 MM Plossl will show more), with the FR I would expect some vignetting, not that I would know because I don't use an FR on my 9.25. The 31MM is the most used EP on my 9.25.
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C9.25 ASGT 9*50 MM Finder,FT Focuser & 2" Diagonal
Meade LXD 75 6 Inch SNT w 9*50 MM Finder
5,6,9,14.5 MM Zhummel Planetary EPs
13,17,21,24,31,36 MM Baader Hyperion
6.7,8.8 MM Meade UWA & 11 MM Nagler T6
Planetary, OIII and Narrowband Filters
Thousand Oaks Dew Control w Kendrick Heaters
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Bill Fischer
super member
Reged: 11/13/08
Posts: 162
Loc: Magnolia, TX and South America
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I am using the FR because I have read on the Celestron website, read comments by Rod Mollise and others about field flattening and over coming other SCT issues for visual use. The stars do seem a little sharper on the edges of the view with the FR. I calculate that with a 2" EP I am able to use the complete 1.5" diameter of the baffle tube and get about a 1.7 degree TFOV on a 31mm EP with a 72 AFOV. I think a longer EP FL will vignette. I have looked through my Q70 in the day time so that I can plainly see the vignette. The 38mm Q70 calculates to a 2 degree TFOV and I am guessing the reduction to 31mm will eliminate the amount of vignette. In the day time I can faintly see the shadow of the secondary. I am thinking that reducing to 31mm will eliminate the shadow. Thank you for the info on the 31mm.
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Nexstar 8 GPS w/Clestron FR/FF
Telrad
TV Pan 35mm
WO UWAN 16mm
TV 11mm, 8mm
Meade 2x Telenegative
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BradleyB
sage
Reged: 09/01/06
Posts: 265
Loc: Olympia, WA
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I use the 31mm in my 12.5" f/6 dob and find it to be an excellent eyepiece. It's comfortable to use, not too big or heavy, gives good views, and what clinches it for me is that you can use the TV Dioptrx on it. It's not a perfect fit but adequate and makes such a difference if your eye has astigmatism.
Brad
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Tom L. made 12.5" f6, "Endurance"
C80ED fixed up
Edmund 60mm f/6
Jason 60mm f/15
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HandyAndy
professor emeritus
Reged: 01/11/08
Posts: 649
Loc: West Midlands and around
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Hi,
I use the eyepiece in an original visual Paracorr with my F5 Dobo and get good results. Like you I chose it as the field stop matches the output field of the Paracorr.
It also works well in my 127mm Triplet Meade.
Cheers. Andrew.
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Monarch 8x42, Zeiss 10x50 WA
10mm F2, Pentax 60mm F5
City: 7" MN78: MK4#2, 10" F6.3: MK4#1, 16" F5 ParaCorr
Country: 8" VISAC: (GP2)
Car: 6" F5 MPCC: SP, 5" 127mm F7.5 (GP2)
TV 55mm, Paragon 40mm, UO Pretoria 28mm
B&L 32 Pl, Clave's 25, 8, 6, 2x
Hyperions 5, 8, 13, 17, 24, 31
Nagler1 9mm, Meade 14mm 4000 UWA
Antares 1.6x, 0.7x, 0.5x
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Bill Fischer
super member
Reged: 11/13/08
Posts: 162
Loc: Magnolia, TX and South America
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My 38mm Q70 worked pretty well without the FR, it gave me 1.3 degrees TFOV, with no vignette in my 2 inch diagonal. I want to leave the FR in all the time. I calculate the 31mm Hyperion will be just right for the max possible TFOV with the 2 inch diagonal and the FR. 41x and 1.7degrees TFOV. With the info received in this thread I think the views through the Hyperion will be a little better than the Q70 so that is also a plus. Thanks for the help.
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Nexstar 8 GPS w/Clestron FR/FF
Telrad
TV Pan 35mm
WO UWAN 16mm
TV 11mm, 8mm
Meade 2x Telenegative
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