Attaching A 1.25" Nose Piece To A 2" eyepiece Question
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Attaching A 1.25" Nose Piece To A 2" eyepiece Question
What percentage of the field of view is lost when attaching a 1.25" inch nose piece to a 2" eyepiece.
- notFritzArgelander
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Re: Attaching A 1.25" Nose Piece To A 2" eyepiece Question
It depends on the size of the field stop of the 2" eyepiece. I estimate that the Baader Hyperion 36mm aspheric has a 43.1mm field stop. Assuming that the nosepiece reduces that to (1.25x25.4) 31.75mm I'd estimate 31.75/43.1 = ~74% is the field remaining for a ~26% loss.
The estimate of the field stop comes from = focal length *AFOV (degrees) / 57.3 (degrees per radian).
The estimate of the field stop comes from = focal length *
Scopes: Refs: Orion ST80, SV 80EDA f7, TS 102ED f11 Newts: AWB 130mm, f5, Z12 f5; Cats: VMC110L, Intes MK66,VMC200L f9.75 EPs: KK Fujiyama Orthoscopics, 2x Vixen NPLs (40-6mm) and BCOs, Baader Mark IV zooms, TV Panoptics, Delos, Plossl 32-8mm. Mixed brand Masuyama/Astroplans Binoculars: Nikon Aculon 10x50, Celestron 15x70, Baader Maxbright. Mounts: Star Seeker IV, Vixen Porta II, Celestron CG5
- Lady Fraktor
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Re: Attaching A 1.25" Nose Piece To A 2" eyepiece Question
It is a bit of a reversal as most adapter eyepieces are 1.25" with a extra 2" barrel, more a convenience than anything.
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Eyepieces: Antares to Zeiss (1011110)
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See Far Sticks: Elita 103/1575, AOM FLT 105/1000, Bresser 127/1200 BV, Nočný stopár 152/1200, Vyrobené doma 70/700, Stellarvue NHNG DX 80/552, TAL RS 100/1000, Vixen SD115s/885
EQ: TAL MT-1, Vixen SXP, SXP2, AXJ, AXD
Az/Alt: AYO Digi II, Stellarvue M2C, Argo Navis encoders on both
Tripods: Berlebach Planet (2), Uni 28 Astro, Report 372, TAL factory maple, Vixen ASG-CB90, Vixen AXD-TR102
Diagonals: Astro-Physics, Baader Amici, Baader Herschel, iStar Blue, Stellarvue DX, Tak prism, TAL, Vixen
Eyepieces: Antares to Zeiss (1011110)
The only culture I have is from yogurt
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Re: Attaching A 1.25" Nose Piece To A 2" eyepiece Question
My calculations are somewhat different. According to Baader 36mm AsphericnotFritzArgelander wrote: ↑Sat Dec 05, 2020 4:04 am It depends on the size of the field stop of the 2" eyepiece. I estimate that the Baader Hyperion 36mm aspheric has a 43.1mm field stop. Assuming that the nosepiece reduces that to (1.25x25.4) 31.75mm I'd estimate 31.75/43.1 = ~74% is the field remaining for a ~26% loss.
The estimate of the field stop comes from = focal length * AFOV(degrees) / 57.3 (degrees per radian).
In a way the 1.25" adapter turns it into a 36mm Plossl right in between 32mm Plossl (49 deg
Last edited by Bigzmey on Mon Dec 07, 2020 6:15 pm, edited 2 times in total.
Scopes: Stellarvue: SV102ED; Celestron: 9.25" EdgeHD, 8" SCT, 150ST, Onyx 80ED; iOptron: Hankmeister 6" Mak; SW: 7" Mak; Meade: 80ST.
Mounts: SW: SkyTee2, AzGTi; iOptron: AZMP; ES: Twilight I; Bresser: EXOS2; UA: MicroStar.
Binos: APM: 100-90 APO; Canon: IS 15x50; Orion: Binoviewer, LG II 15x70, WV 10x50, Nikon: AE 16x50, 10x50, 8x40.
EPs: Pentax: XWs & XFs; TeleVue: Delites, Panoptic & Plossls; ES: 68, 62; Vixen: SLVs; Baader: BCOs, Aspherics, Mark IV.
Diagonals: Baader: BBHS mirror, Zeiss Spec T2 prism, Clicklock dielectric; TeleVue: Evebrite dielectric; AltairAstro: 2" prism.
Filters: Lumicon: DeepSky, UHC, OIII, H-beta; Baader: Moon & SkyGlow, Contrast Booster, UHC-S, 6-color set; Astronomik: UHC.
Solar: HA: Lunt 50mm single stack, W/L: Meade Herschel wedge.
Observing: DSOs: 3106 (Completed: Messier, Herschel 1, 2, 3. In progress: H2,500: 2180, S110: 77). Doubles: 2437, Comets: 34, Asteroids: 257
Mounts: SW: SkyTee2, AzGTi; iOptron: AZMP; ES: Twilight I; Bresser: EXOS2; UA: MicroStar.
Binos: APM: 100-90 APO; Canon: IS 15x50; Orion: Binoviewer, LG II 15x70, WV 10x50, Nikon: AE 16x50, 10x50, 8x40.
EPs: Pentax: XWs & XFs; TeleVue: Delites, Panoptic & Plossls; ES: 68, 62; Vixen: SLVs; Baader: BCOs, Aspherics, Mark IV.
Diagonals: Baader: BBHS mirror, Zeiss Spec T2 prism, Clicklock dielectric; TeleVue: Evebrite dielectric; AltairAstro: 2" prism.
Filters: Lumicon: DeepSky, UHC, OIII, H-beta; Baader: Moon & SkyGlow, Contrast Booster, UHC-S, 6-color set; Astronomik: UHC.
Solar: HA: Lunt 50mm single stack, W/L: Meade Herschel wedge.
Observing: DSOs: 3106 (Completed: Messier, Herschel 1, 2, 3. In progress: H2,500: 2180, S110: 77). Doubles: 2437, Comets: 34, Asteroids: 257
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Re: Attaching A 1.25" Nose Piece To A 2" eyepiece Question
Yours is a better estimate.Bigzmey wrote: ↑Mon Dec 07, 2020 6:09 pmMy calculations are somewhat different. According to Baader 36mm AsphericnotFritzArgelander wrote: ↑Sat Dec 05, 2020 4:04 am It depends on the size of the field stop of the 2" eyepiece. I estimate that the Baader Hyperion 36mm aspheric has a 43.1mm field stop. Assuming that the nosepiece reduces that to (1.25x25.4) 31.75mm I'd estimate 31.75/43.1 = ~74% is the field remaining for a ~26% loss.
The estimate of the field stop comes from = focal length * AFOV(degrees) / 57.3 (degrees per radian).EP field stop is 45mm. Max stop field for 1.25" format is 27mm. This reducesFOV from 72 deg to 43.2 deg (40% loss) with 64% loss in viewed area.
In a way the 1.25" adapter turns it into a 36mm Plossl right in between 32mm Plossl (49 degFOV ) and 40mm Plossl (39 degFOV ).
1) You used an actual field stop spec rather than my use of a formula.
2) My taking the 31.75mm as the field stop is optimistic.
Scopes: Refs: Orion ST80, SV 80EDA f7, TS 102ED f11 Newts: AWB 130mm, f5, Z12 f5; Cats: VMC110L, Intes MK66,VMC200L f9.75 EPs: KK Fujiyama Orthoscopics, 2x Vixen NPLs (40-6mm) and BCOs, Baader Mark IV zooms, TV Panoptics, Delos, Plossl 32-8mm. Mixed brand Masuyama/Astroplans Binoculars: Nikon Aculon 10x50, Celestron 15x70, Baader Maxbright. Mounts: Star Seeker IV, Vixen Porta II, Celestron CG5
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