Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Binoculars - Star Magnitude -Small 'Scopes

This topic has been archived. This means that you cannot reply to this topic.
6 replies to this topic

#1 geoffrey

geoffrey

    Ranger 4

  • *****
  • topic starter
  • Posts: 362
  • Joined: 05 Jan 2004

Posted 07 January 2004 - 04:45 AM

1.Does anybody have a list of Binocular magnification v Star magnitude for say 8x, 10x 15x 18x & 20x

2. Does anyone who uses say 18x or 20x prefer them to their small scope. say 4.5 Reflector or 80mm refractor


Thanks

Geoffrey

#2 EdZ

EdZ

    Professor EdZ

  • *****
  • Posts: 18849
  • Joined: 15 Feb 2002

Posted 07 January 2004 - 06:38 AM

Geoffrey,

I'm at a complete loss to understand your question about "star magnification". Could you please explain what you mean.

edz

#3 geoffrey

geoffrey

    Ranger 4

  • *****
  • topic starter
  • Posts: 362
  • Joined: 05 Jan 2004

Posted 07 January 2004 - 08:19 AM

Sorry Edz,
I did not check my typing. Post now amended to "Star Magnitude" Assume this clarifies?

In other words do you really see all that many more stars with 20x against say 10x.

Geoff

#4 geoffrey

geoffrey

    Ranger 4

  • *****
  • topic starter
  • Posts: 362
  • Joined: 05 Jan 2004

Posted 07 January 2004 - 08:33 AM

I have just answered my own question by this article on Cloudynights:-

http://www.cloudynig...star_counts.htm

However, I would still like to hear from you all which Binos. you prefer for Astronomy, and if anyone prefers the larger Binos. to using a small scope.

Geoff



#5 EdZ

EdZ

    Professor EdZ

  • *****
  • Posts: 18849
  • Joined: 15 Feb 2002

Posted 07 January 2004 - 01:14 PM

Considerably more stars are seen with larger binoculars. Mostly, as magnification increases star counts and limiting magnitude will increase, even if aperture does not increase.

These are some examples of recent observations.

I've been working on studying the Pleiades with various binoculars. So far I've made about 20 observations in various Naked Eye Lim Mag skies, but these should give you a pretty good idea. All of these observations are on the exact same field of stars. You can observe the same field by using one of the charts in the Call for Participation thread.

69 stars/mag9.7 - 8x42 Swift Ultralites skies mag 5.0
85 stars/mag10.1 - 10x50 Orion Ultraviews skies mag 5.0
92 stars/mag10.25 - 12x50 Pentax PCF III skies mag 5.0
103 stars/mag10.4 - 10x70 Fujinon FMT-SX skies mag 5.0
128 stars/mag10.85 - 10x70 Fujinon FMT-SX skies mag 5.6/5.8
97 stars/mag10.2 - 16x60 Pentax PCF V WP skies mag 4.7
141 stars/mag10.74 - 16x60 Pentax PCF V WP skies mag 5.4
106 stars/mag10.3 - 15x70 Oberwerk skies mag 4.7
139 stars/mag10.80 - 15x70 Oberwerk skies mag 5.4
113 stars/mag10.7 - 16x70 Fujinon FMT-SX skies mag 4.7
156 stars/mag10.94 - 16x70 Fujinon FMT-SX skies mag 5.4

Some scopes used for comparison. We can assume a 20% gain from single aperture to binocular (two aperture) viewing, (based on previous tests, refer to the old post one eyed vs two eyed viewing), therefore an 85mm scope is equivalent to 78mm binoculars. A 5"SCT (minus the central obsrtuction has equivalent to 115mm aperture) is equivalent to 105mm binoculars.

118 stars/mag10.7 - TV85 w/27Panoptic (22x85mono) 22x78 mag 4.6 skies
246 stars/mag11.68 - TV85 w/14Radian (43x85mono) 43x78 mag 5.2 skies
262 stars/mag11.46 - G5 (5"SCT)w/30Ultima (45x115mono) 45x105 skies mag 5.2
??? stars/mag12.0 - G5 (5"SCT)w/14Radian (96x115mono) 96x105 skies mag 5.2

It's pretty obvious that magnification increases the number of stars seen and the limit of magnitude of stars reached. Although I may not show you enough to see the trend here, magnification has a much greater impact than aperture on how many stars are seen and what magnitude is reached.

edz


#6 geoffrey

geoffrey

    Ranger 4

  • *****
  • topic starter
  • Posts: 362
  • Joined: 05 Jan 2004

Posted 07 January 2004 - 02:07 PM

Thanks Edz, very kind of you. I am new to all this, but joined a local Ast.Soc. last Sept.
I am interested in the Pleiades, so will try my Opticron 10x50 and old Swift 8x40 whenever we get a clear sky.

Kenny, do you have any info on the old Swift Belmont 8x40's?

I look forward to learning from you all

Regards

Geoffrey

#7 KennyJ

KennyJ

    The British Flash

  • *****
  • Posts: 36399
  • Joined: 27 Apr 2003

Posted 07 January 2004 - 03:27 PM

Thanks ED for that priceless and most interesting list.

Sorry Geoffrey , until recently I must confess to never having heard of the Swift Belmont model.

Like many other binoculars with "well -known manufacturers' names" on their data plate , not ALL Swift binoculars are or were of a particularly good standard , and I have looked through quite a few that were little better than terrible.

The original "Audubon" Porro in 8.5 x 44 and the subsequent "big brother" model 826 10 x 50 "Audubon Kestrel"
really were for a long time the "jewel in the crown" of Swift binoculars.

In fact can only speak from other reports about the various "newer" Swift Audubons , some of which are Porros and some of which are Roofs --and some of which have E.D glass and some of which have not.

It gets VERY confusing even for ME -- and I really do try to keep on top of these things.

I doubt if any of them are much , if any , better than the best of the Opticrons to be perfectly honest.

Regards --Kenny.


CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics