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Binoculars field of view in degrees
How would I find the field of view in degrees for a pair of binoculars given
the following info: 16x50 binoculars with eye relief of 10mm and exit pupil of 3.1mm. Terra field of view is 182'@1000 yards. Thanks. : ) FOV= (182*ft/3000*ft)*57.3=3.5 degrees Jon |
#2
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Binoculars field of view in degrees
"riff" wrote in message news:wzm7b.3259$pe.1704@lakeread06... How would I find the field of view in degrees for a pair of binoculars given the following info: 16x50 binoculars with eye relief of 10mm and exit pupil of 3.1mm. Terra field of view is 182'@1000 yards. What's the problem? You've got all the information you need. If the field is 182' at 3000', then the angle is (to an excellent approximation: 182/3000 = 0.061 radians = 3.5 degrees A rather small field of view, as you'd expect from an excessively high magnification! Regards, Chris |
#3
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Binoculars field of view in degrees
"Chris Marriott" wrote in message ... "riff" wrote in message news:wzm7b.3259$pe.1704@lakeread06... How would I find the field of view in degrees for a pair of binoculars given the following info: 16x50 binoculars with eye relief of 10mm and exit pupil of 3.1mm. Terra field of view is 182'@1000 yards. What's the problem? You've got all the information you need. Well...now I do : ) If the field is 182' at 3000', then the angle is (to an excellent approximation: 182/3000 = 0.061 radians = 3.5 degrees Geez. Is that all I needed to do? A rather small field of view, as you'd expect from an excessively high magnification! Thanks! Now I have "measured" proof of what I see and you're right. Small field of view for constellations. Not bad for the moon though. Thanks for helping an old fart out Chris. ; ) -Bob |
#4
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Binoculars field of view in degrees
"Jon Isaacs" wrote in message ... How would I find the field of view in degrees for a pair of binoculars given the following info: 16x50 binoculars with eye relief of 10mm and exit pupil of 3.1mm. Terra field of view is 182'@1000 yards. Thanks. : ) FOV= (182*ft/3000*ft)*57.3=3.5 degrees Jon Thanks Jon -Bob |
#5
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Binoculars field of view in degrees
"riff" wrote in message newsun7b.3262$pe.3020@lakeread06... "Chris Marriott" wrote in message ... "riff" wrote in message news:wzm7b.3259$pe.1704@lakeread06... How would I find the field of view in degrees for a pair of binoculars given the following info: 16x50 binoculars with eye relief of 10mm and exit pupil of 3.1mm. Terra field of view is 182'@1000 yards. What's the problem? You've got all the information you need. Well...now I do : ) If the field is 182' at 3000', then the angle is (to an excellent approximation: 182/3000 = 0.061 radians = 3.5 degrees Geez. Is that all I needed to do? A rather small field of view, as you'd expect from an excessively high magnification! Thanks! Now I have "measured" proof of what I see and you're right. Small field of view for constellations. Not bad for the moon though. Thanks for helping an old fart out Chris. ; ) Sorry, Bob; on reading my reply to you it sounds rather abrupt. It wasn't intended to be that way; please excuse me! Regards, Chris |
#6
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Binoculars field of view in degrees
"Chris Marriott" wrote in message ... snip Sorry, Bob; on reading my reply to you it sounds rather abrupt. It wasn't intended to be that way; please excuse me! Regards, Chris Heh. Thanks Chris. Actually, I know it must be frustrating for you and the other very helpful and well informed guys in this group to answer the obvious and perhaps simple questions. I'm just thankful for a resource like this and for your taking the time to respond. A follow-up if I may. Do you or anyone else know of a good site or internet resource for _basic_ telescope optic formulas such as what you shared? I'm a noob to this (quite obviously) and would be more interested in "less academic/more lay-person friendly" sort of info. I did make use of Google and found a few links but didn't know if anyone has a favorite or two. Many thanks. -Bob |
#7
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Binoculars field of view in degrees
"Jon Isaacs" wrote in message ... How would I find the field of view in degrees for a pair of binoculars given the following info: 16x50 binoculars with eye relief of 10mm and exit pupil of 3.1mm. Terra field of view is 182'@1000 yards. Thanks. : ) FOV= (182*ft/3000*ft)*57.3=3.5 degrees Further, apparent field is that times the magnification, or in this case 3.5 * 16 = 56 degrees. Apparent field is about 50 for conventional binoculars, 60 or 70 for wide-angle ones. Conventional ones are sharper. |
#8
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Binoculars field of view in degrees
Bob, I wanted to summarized here some info I've collected on
binoculars so others could see: Wide-angle binoculars can have narrow Afov eyepieces and Narrow angle binoculars can have wide Afov eyepieces. Except at the narrowest and widest extremes of True field of view, there is no standard rule you can follow. The way I have arranged these groups is based on personal use preference. You may think otherwise, but my thoughts are after hundreds of hours of use. Most binoculars do not actually measure in the field what is stated for Tfov. Usually the higher cost premium binoculars do measure as stated. Half of all binoculars I measured have Afov eyepieces between 60° and 65°. They cross a range from narrow to wide True field of view. There are some but few wider eyepieces in use. What may seem like a narrow 4° field of view would be wide for a 15x or 16x binocular. A 3.5° field of view would be wide for a 20x binocular. On the other hand, a True field of view less than 3.0° is extremely narrow for ANY binocular. Some wide Afov eyepieces have excellent performance. Fujinon 16x70 and Oberwerk 15x70 use 64° Afov eyepieces and are sharp to 80%+ Tfov. In comparison, Orion 16x80 uses a narrower 53° Afov eyepiece and its sharpness characteristics are poor in the outer 40% Tfov. Some of the newer 22x and 25x binoculars coming on the market are advertised as 3.5° Tfov, but are measuring less than stated. If the newer 22x an 25x binoculars measure over 3.0° Tfov, they are using eyepieces with Afov approx. 66° to 75°, wider eyepieces than anything I have seen to date. The 8x binoculars with a 6.5° field of view may be considered the low end of a wide True field of view for that power binocular. This Tfov is not produced with a wide Afov eyepiece. They are sharp to 80% of the True field of view. edz NARROW True Field of View Pentax PCF V 20x60 Tfov 2.2 Afov 44 Pentax PCF V 16x60 Tfov 2.8 Afov 45 Orion Giant 16x80 Tfov 3.3 Afov 53 Oberwerk Deluxe 20x80 Tfov 3.3 Afov 65 STANDARD True Field of View Fujinon FMT-SX 16x70 Tfov 4.0 Afov 64 Pentax PCF III 12x50 Tfov 4.2 Afov 50 Oberwerk 15x70 Tfov 4.3 Afov 64 Nikon S&E Kestrel 10x50 Tfov 4.9 Afov 49 Minolta Standard XL 12x50 Tfov 5.1 Afov 61 WIDE True Field of View Orion Ultraview 10x50 Tfov 6.0 Afov 60 Orion Vista 8x42 Tfov 6.5 Afov 52 Swift Ultralite 8x42 Tfov 6.6 Afov 53 Minolta Standard XL 7x35 Tfov 9.0 Afov 63 Minolta Activa 7x35 Tfov 9.3 Afov 65 NARROW Apparent Field of View Pentax PCF V 20x60 Tfov 2.2 Afov 44 Pentax PCF V 16x60 Tfov 2.8 Afov 45 Nikon S&E Kestrel 10x50 Tfov 4.9 Afov 49 Pentax PCF III 12x50 Tfov 4.2 Afov 50 Orion Vista 8x42 Tfov 6.5 Afov 52 Swift Ultralite 8x42 Tfov 6.6 Afov 53 Orion Giant 16x80 Tfov 3.3 Afov 53 WIDE Apparent Field of View Orion Ultraview 10x50 Tfov 6.0 Afov 60 Minolta Standard XL 12x50 Tfov 5.1 Afov 61 Minolta Standard XL 7x35 Tfov 9.0 Afov 63 Fujinon FMT-SX 16x70 Tfov 4.0 Afov 64 Oberwerk 15x70 Tfov 4.3 Afov 64 Minolta Activa 7x35 Tfov 9.3 Afov 65 Oberwerk Deluxe 20x80 Tfov 3.3 Afov 65 |
#9
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Binoculars field of view in degrees
"edz" wrote in message om... Bob, I wanted to summarized here some info I've collected on binoculars so others could see: Wide-angle binoculars can have narrow Afov eyepieces and Narrow angle binoculars can have wide Afov eyepieces. Except at the narrowest and widest extremes of True field of view, there is no standard rule you can follow. Not as I understand it. Binoculars are not called wide-angle unless the field of view is wide *relative to their magnification*. That means wide AFOV, always. For example, 6x binoculars with a 7-degree field are not wide-angle, but 10x binoculars with a 7-degree field definitely are wide-angle. The AFOVs are 42 and 70 degrees respectively. Some cheap binoculars may be labeled "wide-angle" regardless of their field. -- Clear skies, Michael Covington -- www.covingtoninnovations.com Author, Astrophotography for the Amateur and (new) How to Use a Computerized Telescope |
#10
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Binoculars field of view in degrees
"edz" wrote in message om... "Michael A. Covington" wrote in message ... Not as I understand it. Binoculars are not called wide-angle unless the field of view is wide *relative to their magnification*. That means wide AFOV, always. For example, 6x binoculars with a 7-degree field are not wide-angle, but 10x binoculars with a 7-degree field definitely are wide-angle. The AFOVs are 42 and 70 degrees respectively. Some cheap binoculars may be labeled "wide-angle" regardless of their field. Hi Michael, From practical experience I find binoculars over 6° Tfov are wide. But standard 7x50 binoculars have a 7-degree field and are not labeled "wide-angle". To the manufacturers and dealers, "wide-angle" means "a wider angle than the usual binoculars of this magnification." In practice it means "apparent field appreciably more than 50 degrees." I'm not talking about whether it seems wide to you -- I'm talking about the meaning of the term in product descriptions. There are normal 7x binoculars and wide-angle 7x binoculars. Likewise there are normal 12x binoculars and wide-angle 12x binoculars. The true field of the wide-angle 12x may well be less than the true field of the ordinary 7x. |
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