Difraction Rings

Discussion of optical systems and their characteristics.
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Jones
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Difraction Rings

#1

Post by Jones »


Why does my 6"f6 GSO newt show a prominent 1st difraction ring,
while the Edmund 6"f8 reveals just a faint one?

Neither could see the 'f' star in the Trapezium.
Arizona- where the sky's are not cloudy all night.

Triple lensed fracs are so yummy when looking at planets.
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Bigzmey United States of America
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Re: Difraction Rings

#2

Post by Bigzmey »


I believe it has to do with F-ratio and size of the central obstruction. The larger central obstruction the more light is distributed from the airy disk to the first diffraction ring. Faster newts tend to have lager secondary mirrors compared to slower.
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.

Observing: DSOs: 3106 (Completed: Messier, Herschel 1, 2, 3. In progress: H2,500: 2180, S110: 77). Doubles: 2407, Comets: 34, Asteroids: 255
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