You may have noticed our new Astrophotography Calculator tool so we thought we’d better explain it a little!
First, put in your focal length and F-number for your telescope and hit calculate. If you’re not sure of this info check the specifications of your telescope. If you bought it from us, this info will be on the telescope’s product page of our website. No big surprises, it will tell you the maximum magnification and the aperture which you probably already know.
Now enter in your camera’s pixel size in µm, and resolution width and height in pixels and hit calculate again. Now we’ll start to get some interesting and useful information!
Or, perhaps you aren’t using a camera – the calculator also supports eyepieces. Just add your Eyepiece “mm” in the first field, and the “FOV” in the second. Note, this FOV isn’t the “true field of view” which the calculator will generate but it can be founds in the specifications of your eyepiece.
What The Results Mean
It will tell you (in arcseconds) how much of the sky gets registered on a single pixel. This by itself makes more sense with an actual preview which we also include but it also tells you whether the particular combination of telescope + camera gives you an oversampled or undersampled image. The ideal range with average seeing conditions is 0.67″-2″ arcseconds.
Oversampling isn’t necessarily bad, it gives you nice smooth rounded stars, but there may be too many pixels than actually needed for the level of detail the telescope is capable of. You won’t necessarily get any more detail, unless the seeing is spectacular.
Undersampling is the opposite problem. Stars might only hit one, or a few pixels and appear blocky and jagged, this is definitely a worse problem to have.
Camera Chip FOV (Field of View)
In degrees, this result shows you how much of the sky (width x height) you can capture in a photo with the telescope and camera details you’ve entered. Again this might make more sense to you with the preview targets we’ve included.
Eyepiece True Field of View
In degrees, this result shows you how much of the sky the circular shape of the eyepiece will view edge-to-edge.
By default, the calculator will show you an outline of the moon and a red rectangle for your chip, or blue circle for your eyepieces, to give you a sense of how much (or how little) of the moon you’ll be able to see with the entered setup. It’s worth trying various barlows, reducers and/or binning options to see how much versatility you’ll get out of the setup. We’ve also included several other preview targets ranging from the very small (Saturn) to the very big (Andromeda) to make simulation of a wide range of optics and cameras possible.
Feel free to give us some feedback, and we hope this helps you when choosing an astrophotography setup! If you have any questions or just need advice, be sure to contact the Bintel team of astronomy experts to guide you through.