Scientific calculator
Temperature converter
This free script provided by
JavaScript
Kit
Telescope simulator
This is really cool! I especially like the simulator rather than the comparison because the simulator let's you put in your own numbers - not simply choose from a limited list. In any event, this is a great way to actually see what different scopes and eyepice combinations will reveal of common objects. Go here.
Special astronomy calculators
There's a whole page of highly specialized calculators at Wilmslow Astro. They include:
- Eyepiece apparent vs real field of view
- CCD arc-sec/pixel and focal ratio
- Focal reducers
- Eyepiece Projection
- CCD Dust Shadows
- CCD Filter Reflections
- Visual limiting magnitude
- Signal to noise ratio
- Size of Airy disk
- Mount Periodic Error
- Star trail lengths
Eyepiece Calculator
While the calculator popup reached from this page is specific to Televue eyepices, there are so many Televue eyepieces of various focal lengths and apparent fields of view, that I find it an excellent way to get a quick idea of what just about any eyepice will do in your scope. All the useful parameters are included and all you need to know is the focal length and focal ratio - or objective size - of your scope. -