A Question

[refractordude]

What is the field of view of 15x65.5 binoculars.

[Stu]

23 minutes ago, refractordude said:

What is the field of view of 15x65.5 binoculars.

You can’t necessarily tell as it depends on the focal length and apparent field of view of the eyepieces. Do you have any more details of them? It is normally written on the top of the housing.

[lenscap]

To give you a rough idea Celestron 15x70's have 4.4 degree FOV while Opticron 15x70's have 4.8 degrees.

[refractordude]

2 hours ago, Stu said:

You can’t necessarily tell as it depends on the focal length and apparent field of view of the eyepieces. Do you have any more details of them? It is normally written on the top of the housing.

The stated aperture of the Oberwerks is 70mm. I discovered that the true aperture is 65.5mm, which Oberwerk does not state in their advertising. Oberwerk has the FOV at 4.3 degrees. Is 4.3 degrees a correct number for 65.5 aperture? These are the binoculars I have questions about. https://oberwerk.com/product/11x70mm-lightweight-binoculars/

[lenscap]

The fov of a refractor is    (eyepiece field -stop diameter / objective focal length)   radians.    Multiply by 57.3 to get degrees.

For a given objective lens, stopping down the aperture makes the image a bit dimmer but does not reduce the fov.

Stopping down objectives is a common means of slightly reducing aberations and manufacturing cost. So there is no reason to doubt the 4.3 degrees quoted.

[BinocularSky]

On 07/08/2018 at 21:55, refractordude said:

I discovered that the true aperture is 65.5mm,

As a matter of interest, how did you discover that? Blooming lucky if it's correct: every one I've measured has been more like 62.5 mm.

[Dheneb]

On ‎07‎/‎08‎/‎2018 at 21:36, lenscap said:

To give you a rough idea Celestron 15x70's have 4.4 degree FOV while Opticron 15x70's have 4.8 degrees.

Exactly. I just got a new Celestron 15x70 (cost 75 Eur), they look impressive. I can't wait when I'll be able to test them, hopefully on the next week. I will keep you posted about my findings.

Clear skies!

 

[refractordude]

8 hours ago, BinocularSky said:

As a matter of interest, how did you discover that? Blooming lucky if it's correct: every one I've measured has been more like 62.5 mm.

I called the Oberwerk tech guy. He told me himself. I cant recall his name. https://oberwerk.com/contact-us/

[BinocularSky]

On 09/08/2018 at 20:17, refractordude said:

 I cant recall his name.

Kevin Busarow?