Binocular Focal Length and Stellarium

[mikerr (Michael)]

I would like to enter my 10x70 fujinon Binoculars into Stellarium as a telescope to see the view I can expect when using the OCULAR function.

1/ What is the Focal Length to enter?

2/ Do I use 140 as the diameter?

3/ What Ocular information do I enter?

4/ The Binoculars state a "Field 5 degrees 18' "

5/ What FOV setting in Stellarium equates to naked eye viewing?

Thanks

Michael

[rmcconachy]

G'day Michael,

I cannot remember the exact details of the Fuji 10x70 objectives but they are about f/4 or a little quicker. You should be able to use answers something like:

1/ Focal length = 280mm
2/ Objective diameter = 70mm (two eyes by 70mm each is not the same as 140mm, a good starting point is to pretend that it is a 70mm aperture telescope)
3/ Ocular focal length 28mm (yields 10x) and apparent field of view 53° (yields 5°18' true FOV)
4/ The Fuji FMT 10x70 does indeed have a 5°18' (or 5.3° if you prefer) true FOV
5/ I've no idea what Stellarium uses but a typical human field of view is something like ~100° vertically and quite a bit more laterally (much of it low resolution peripheral vision)

All the best!

[mikerr (Michael)]

Thanks very much for the detailed reply.
I really appreciate the time and effort you have gone to.

Rgds

Michael