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# Field Of View Relative To Star Charts?

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### #1 Guest_**DONOTDELETE**_*

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Posted 12 January 2004 - 02:26 AM

Please bear with me with this post as it is, in part, possibly a little off topic, but the reason for the question is directly related to binoculars, so here goes:

Does anyone know how to go about mapping a field of view for a binocular to a star chart?

If I have a bino with say a 6* FOV, how can this be trabnslated to a 6* circle on a sky chart?

Ideally, I would like to make up a template on a clear laminate sheet with a series of concentric circles for the various FOV possibilities for my equipment and binos that will show 5*, 6*, 6.5* and 7* FOV circles relative to my Cambridge Star Atlas scale. This would allow me to simply lay this over an area of the sky chart and see what "view" I would get through my different binoculars...

Any ideas?

### #2 EdZ

EdZ

Professor EdZ

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Posted 12 January 2004 - 05:49 AM

Looking at the star chart, you may be confused trying to convert Right Ascension to degrees. But look again. Declination is already in degrees and you have lines on your charts every 10° north to south. Measure the distance between any two adjacent declination lines. Thats 10°. Cambridge Star Atlas is 33mm per 10°. Work out a 6° circle from there. It will be a 6° circle anywhere on your set of charts. Therefore it would be ~20mm to represent 6° anywhere on the charts.

edz

### #3 Guest_**DONOTDELETE**_*

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Posted 12 January 2004 - 06:54 PM

Edz... Sometimes it's the simple things in life! :o

Found it and it is so simple when you actually see it

Many thanks...

### #4 edcannon

edcannon

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• Joined: 19 Nov 2003

Posted 13 January 2004 - 01:15 AM

Frilby, what a good idea! I've been using the Bright Star Atlas 2000 for maybe four years now but have never gotten a very good idea of what size chunk of sky I'm seeing in the FOV. I'm going to try to make something like your circles!
You should make 8.2 degrees as well, just for comparison!

Ed Cannon - ecannon@mail.utexas.edu - Austin, Texas, USA

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