Field of View calculator

15 February 2019

Telescope simulator - such a handy website!

Probably the number one question we get from our customers is what they'll be able to see in their telescopes. I have to say, it's the first thing I'd be asking too.

Mostly, people want to know about magnification. How big will Saturn be in the scope? Will the Moon be larger than the field?

Well, you can find out using this website!

Go to 12 Dimensional String's field of view calculator website. Here, you can input your telescope's optics, set a target and see a photo in a circular field that will show you how big the target is going to be. (Watch out though, it's only about magnification. It doesn't show you how bright it's going to be.)

First, set the mode to "eyepiece", and set a target. M42, the Orion Nebula, is the default, but you can select other Messier catalogues, solar system objects like Saturn or the Moon, or NGC catalogues like NGC 2516 - the Diamond Cluster.

Next, you put in the focal length of your telescope and the focal length of the eyepiece. You can also add additional details like Barlows or field of view (FOV) of the eyepiece if you have them, but it's not necessary.

You'll notice there are a number of preset telescope and eyepiece makes and models, but all you really need is the focal length of the telescope which is helpfully written on the side of saxon scopes, and the focal length of your eyepiece (also written on the eyepiece).

The three pictures I've attached are for a saxon Novo 909 refractor with a Super 10mm eyepiece pointed at the Moon, Jupiter and the Diamond Cluster. This should give you a pretty good idea as to what you should be able to see for these bright objects.

Have a play with the website. Swap your eyepieces. You'll find cameras as well, for when you connect your DSLR to your telescope.