Power And Aperture In Binoculars

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Refractordude
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Power And Aperture In Binoculars

#1

Post by Refractordude »


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Michael131313 Mexico
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Re: Power And Aperture In Binoculars

#2

Post by Michael131313 »


Thanks very much. Good article.
ES AR 102 102mm, f/6.5, ES 254mm f/5 DOB, Obie 10x50, GSO SV 30mm, ES 68° 20mm, ES 82° 14mm, 11mm, 8.8 mm, 6.8mm, 4.7mm. Twilight 1 mount.
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Makuser United States of America
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Re: Power And Aperture In Binoculars

#3

Post by Makuser »


Hello Refractordude. This is an excellent article and explains a lot of good rules for selecting and using binoculars. I have always followed the 6mm or less exit pupil rule. And, as your eyes get older, the dilation of the pupils becomes less. For example, my old Focal (Kamakura Optics) 7x35mm binoculars result in an exit pupil of 5mm. My much newer Celestron 15x70mm binoculars result in an exit pupil of 4.66mm. And, this is important even after your eyes have become dark night adapted with the rhodopsin having been released.
https://en.wikipedia.org/wiki/Rhodopsin
Thanks for this informative link Refractordude, and the best of regards.
Marshall
Sky-Watcher 90mm f/13.8 Maksutov-Cassegrain on motorized Multimount
Orion Astroview 120ST f/5 Refractor on EQ3 mount
Celestron Comet Catcher 140mm f/3.64 Schmidt-Newtonian on alt-az mount
Celestron Omni XLT150R f/5 Refractor on CG4 mount with dual axis drives.
Orion 180mm f/15 Maksutov-Cassegrain on CG5-GT Goto mount.
Orion XT12i 12" f/4.9 Dobsonian Intelliscope.
Kamakura 7x35 Binoculars and Celestron SkyMaster 15x70 Binoculars. ZWO ASI 120MC camera.
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Re: Power And Aperture In Binoculars

#4

Post by Ylem »


Thanks for posting that one.
I haven't seen that article before.

Lately of been using my binos more and more.
Clear Skies,
-Jeff :telescopewink:


Member; ASTRA-NJ



Orion 80ED
Celestron C5, 6SE, Celestar 8
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Re: Power And Aperture In Binoculars

#5

Post by Peter802 »


Great article. Thank you for posting.
Clear Skies.
Regards,

Peter
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Re: Power And Aperture In Binoculars

#6

Post by helicon »


Very nice article - and useful, thanks for posting.
-Michael
Refractors: ES AR152 f/6.5 Achromat on Twilight II, Celestron 102mm XLT f/9.8 on Celestron Heavy Duty Alt Az mount, KOWA 90mm spotting scope
Binoculars: Celestron SkyMaster 15x70, Bushnell 10x50
Eyepieces: Various, GSO Superview, 9mm Plossl, Celestron 25mm Plossl
Camera: ZWO ASI 120
Naked Eye: Two Eyeballs
Latitude: 48.7229° N
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Re: Power And Aperture In Binoculars

#7

Post by pakarinen »


I kinda wonder about his quick rating system: 10x50s = 500, 20x60s = 1200, 15x70s = 1050. The 60s are rated highest, but they only have a 3mm exit pupil. Seems to me 3mm is pushing things or am I missing something here?
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I drink tea, I read books, I look at stars when I'm not cursing clouds. It's what I do.
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AT50, AT72EDII, ST80, ST102; Scopetech Zero, AZ-GTi, AZ Pronto; Innorel RT90C, Oberwerk 5000; Orion Giantview 15x70s, Vortex 8x42s, Navy surplus 7x50s, Nikon 10x50s
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Re: Power And Aperture In Binoculars

#8

Post by Refractordude »


I just returned a pair of 10x50 binoculars. The 7x50 works best for me. The clarity is just best for my physiology. I may get a pair of the APM 7x50 ED before Spring. The Levenhuks that I have are really good, but I want something wider than 5.7 degrees. I was just out back looking at the Moon with passing clouds. Everyone should own a pair of low mag wide field binoculars. The Levenuks can bring Aldebaran, Ain, and Prima Hyadum into view with surrounding stars. Dual refractors/binoculars rock. Left click the image.
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messier 111 Canada
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Re: Power And Aperture In Binoculars

#9

Post by messier 111 »


very good article , thx
I LOVE REFRACTORS , :Astronomer1: :sprefac:

REFRACTOR , TS-Optics Doublet SD-APO 125 mm f/7.8 . Lunt 80mm MT Ha Doublet Refractor .

EYEPIECES, Delos , Delite and 26mm Nagler t5 , 2 zoom Svbony 7-21 , Orion Premium Linear BinoViewer .

FILTER , Nebustar 2 tele vue . Apm solar wedge . contrast booster 2 inches .

Mounts , berno mack 3 with telepod , cg-4 motorized , eq6 pro belt drive .

“Your assumptions are your windows on the world. Scrub them off every once in a while, or the light won't come in.”
― Isaac Asimov

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Re: Power And Aperture In Binoculars

#10

Post by notFritzArgelander »


pakarinen wrote: Mon Nov 16, 2020 5:02 pm I kinda wonder about his quick rating system: 10x50s = 500, 20x60s = 1200, 15x70s = 1050. The 60s are rated highest, but they only have a 3mm exit pupil. Seems to me 3mm is pushing things or am I missing something here?
It depends. A 3mm exit pupil isn't bad for looking at large faint fuzzies. If you're in an are of light pollution it might work better than a 5mm exit pupil.
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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Re: Power And Aperture In Binoculars

#11

Post by John Baars »


I ran into the Bishop visibility factor several years ago in the May copy 1995 of Sky & Telescope. An article by A. MacRoberts.
Holger Merlitz referred in his book "Handferngläser", 2019 Verlag Europa-Lehrmittel, to three other publicists about the matter. ( How good is your reading technical German language? It'd better be excellent)
It comes down that the four calculation methods do not differ all that much in their outcome. Bishop's method is by far the easiest to remember.
All methods are based on magnitude 6 or better naked eye limit.

In my experience and apparently of notFritzArgelander too, much depends on the light pollution.
A 3mm exit pupil isn't bad for looking at large faint fuzzies. If you're in an are of light pollution it might work better than a 5mm exit pupil.
For instance: M42 in a 20X60 is even a bit more impressive than in a 20X80 under light polluted skies. ( exitpupil 3 mm versus exitpupil 4 mm) Darker background, so more contrast with its background. Under really dark skies, the 20X80 might be more impressive.

The high numbers of the Bisshop calculation might lead to false expectations though. 500 against 1600 for instance for a 10X50 against a 20X80. It seems a giant leap but in reality it is only a difference of 1.3 magnitudes. Visible of course, but not as spectacular as it seems when you hear 500 versus 1600. Knowing this, a difference of 250 on the Bishop scale might not be that impressive as one might expect.
Refractors in frequency of use : *SW Evostar 120ED F/7.5 (all round ), * Vixen 102ED F/9 (vintage), both on Vixen GPDX.
GrabnGo on Alt/AZ : *SW Startravel 102 F/5 refractor( widefield, Sun, push-to), *OMC140 Maksutov F/14.3 ( planets).
Most used Eyepieces: *Panoptic 24, *Morpheus 14, *Leica ASPH zoom, *Zeiss barlow, *Pentax XO5.
Commonly used bino's : *Jena 10X50 , * Canon 10X30 IS, *Swarovski Habicht 7X42, * Celestron 15X70, *Kasai 2.3X40
Rijswijk Public Observatory: * Astro-Physics Starfire 130 f/8, * 6 inch Newton, * C9.25, * Meade 14 inch LX600 ACF, *Lunt.
Amateur astronomer since 1970.
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Re: Power And Aperture In Binoculars

#12

Post by Refractordude »


My home night sky is so light polluted I do not bother with DSO. Andromeda looks like the size of slightly transparent Brazil nut, and that is with a 6" aperture refractor. At Maryland's Point Lookout State Park, brighter galaxies are no problem with 7x50 binoculars. Left click the image.
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