FOV

[shropshire lad]

Hi.. Can anyone tell me what the fov will be for my camera 70-200mm lens.. 

And what is the fov of the moon.

Thanks in advance

 

 

[wimvb]

Check this

http://astronomy.tools/calculators/field_of_view/

The moon has an angular size of about 0.5 degrees

[wulfrun]

What camera and what zoom setting? If you know the sensor diagonal, you can calculate it as 57.3 * D /FL, where D is the sensor diagonal in mm) and FL is the lens focal length (in mm). I hope I got that right!

Edited December 7, 2020 by wulfrun

[shropshire lad]

 

55 minutes ago, wulfrun said:

What camera and what zoom setting? If you know the sensor diagonal, you can calculate it as 57.3 * D /FL, where D is the sensor diagonal in mm) and FL is the lens focal length (in mm). I hope I got that right!

Canon 80D was hoping to get the FOV of both ends... 70mm and 200mm.

56 minutes ago, wimvb said:

Check this

http://astronomy.tools/calculators/field_of_view/

The moon has an angular size of about 0.5 degrees

Thanks for that but the site is a bit confusing to me ... as it shows Telescope and eyepiece, and I have neither.

 

[wulfrun]

If the info I can find is correct, it's 27.04mm diagonal. Plugging that into the formula says 22 degrees @ 70mm and 7.75 degrees @ 200mm. It may not be exact but it'll be close to that.

[Alien 13]

9 minutes ago, shropshire lad said:

 

Canon 80D was hoping to get the FOV of both ends... 70mm and 200mm.

Thanks for that but the site is a bit confusing to me ... as it shows Telescope and eyepiece, and I have neither.

 

Just switch the view to imaging mode, most Canon cameras are listed as well as some lenses but you can just add your own info.

Alan

[shropshire lad]

Ok thanks everyone that answers my question and I have a chart I can look up if I chose a different lens.

 

[wimvb]

42 minutes ago, shropshire lad said:

Thanks for that but the site is a bit confusing to me ... as it shows Telescope and eyepiece, and I have neither.

 

There is an Imaging Mode on that site. You can enter a custom telescope (= lens), where you specify focal length and aperture (FL / F-number). For a 70 mm lens at f/4, the focal length = 70 and aperture = 70/4 = 17.5

Here's the moon at 70 mm with a Canon camera

[shropshire lad]

Thanks @wimvb for that, but surely the f stop wont affect the FOV will it, 

[Alien 13]

3 minutes ago, shropshire lad said:

Thanks @wimvb for that, but surely the f stop wont affect the FOV will it, 

Very few camera lenses quote the aperture so this needs to be calculated from the f/ratio as follows A=fl/f ratio.

Alan 

[wimvb]

1 hour ago, shropshire lad said:

Thanks @wimvb for that, but surely the f stop wont affect the FOV will it, 

No, but it will determine the optical resolution of the lens (so called Dawes limit), ie if two stars that are close to each other, can be separated in the view.