How to understand and calculate binocular field of view

[Paul Riley]

Having read a few articles on binoculars I am now wondering if there is a single sure way/formula for calculating your field of view?.Is it linked to the aperture size of the binoc?.

Having a pair with x 70 aperture would I have a relatively comfortable view of objects? I understand that 5 degrees FOV is the absolute minimum (5 degree being half of the active cone of attention for the eyes) before strain on the eye becomes quite apparent,therefore using that knowledge around 8 degrees would seem perfect.

I still have yet to properly use my new binocs out in the field so havent really tested them yet on anything worth looking at,mainly because of the blumming clouds lately.

EDIT - would holding one finger to your view correspond approx 1 degree of FOV?

Thanks.

Paul.

[Paul Riley]

It appears they have a FOV of 4.1 deg , is this too narrow for the eyes to cope with?

Below is a quick reference of the binoc specs -

Specification:

Aperture: 70mm

Magnification: 15x

Brightness:16.00

Field of view: 70m @ 1000m (210ft @ 1000yds) or 4.1 degrees

Dim. (mm): 270 x 83 x 205 Weight: 1360g

[John]

It appears they have a FOV of 4.1 deg , is this too narrow for the eyes to cope with?

Below is a quick reference of the binoc specs -

Specification:

Aperture: 70mm

Magnification: 15x

Brightness:16.00

Field of view: 70m @ 1000m (210ft @ 1000yds) or 4.1 degrees

Dim. (mm): 270 x 83 x 205 Weight: 1360g

They seem a perfectly normal set of specs for 15x70's to me. You will need a tripod for them for any extended viewing - unless you are very strong that is

You won't find 15x70 binoculars that give you and 8 degree field I think - my 8x40's do give around that though but are more suited to birdwatching than astronomy.

[Paul Riley]

They seem a perfectly normal set of specs for 15x70's to me. You will need a tripod for them for any extended viewing - unless you are very strong that is

You won't find 15x70 binoculars that give you and 8 degree field I think - my 8x40's do give around that though but are more suited to birdwatching than astronomy.

Thanks for the reply.

Well,last night I decided to go out in the back yard with them for a short while as Jupiter was out to the south (the real bright star we have had for a while now?) and it looked fantastic!,real nice and clear and I could even see,albeit faintly a second star/moon that was otherwise invisible.The rain did make things a little tough though on the lenses trying to focus,but still,we cant have it all our own way.

Quite comfortable indeed

Oh,the wobble was pretty bad,and my arms are not weak by any means.A tripod WILL be needed.I am thinking of one of those unique shaped ones that allow you to view while laid back in a deck chair for example.