Scope Calculator 3

Scope Calculator 3 is tool for determining and comparing the characteristics of eyepieces when used with a given telescope, for example, magnification and exit pupil. It is designed to be a simple and flexible alternative to doing these calculations on a traditional spreadsheet program such as Excel.

Installation

Place the application in the folder of your choice. The Macintosh version of Scope Calculator 2 is designed to work on any computer running OS X, the Windows version on any computer running Windows XP or better.

Quick Start

Launch the application. The top half contains two sliders that allow you to quickly enter the aperture and focal length of your telescope. Use the up/down arrows on the far right of the window to nudge the values up or down one millimetre at a time. The bottom half of the application is a tabbed panel that by default opens up with the settings for Eyepiece 1. By clicking on the tabs you can toggle between Eyepiece 1 and Eyepiece 2. Again, there are sliders and up/down arrows for entering eyepiece settings, in this case the apparent field of view (AFOV) in degrees and the focal length in millimetres.

As you move the sliders, the magnification, true field of view, and exit pupil values will change. Toggling between Eyepiece 1 and Eyepiece 2 lets you compare different eyepieces.

Barlow and Reducer-corrector lenses

Clicking on the Barlow and R/C buttons at the bottom of the window toggle whether or not these particular lenses are being used. Click the button once to apply the lens, and click a second time to remove the lens.

Note that when they are used, the telescope focal length, displayed at top left, changes.

Telescope Menu

You can select from a selection of pre-determined telescope settings from the Telescope menu.

Development

Scope Calculator started off as a HyperCard stack that allowed comparison of multiple eyepieces all at the same time. As this morphed through Revolution and REALbasic versions, the idea stayed the same even though the implementation changed. With Scope Calculator 3, the whole idea has changed, with the use of sliders to make it easier to enter the key data while removing the problem of entering the wrong numbers in the wrong boxes.

3.0 -- Ground-up reworking of the idea; instead of storing eyepiece data, it’s a tool for quickly comparing eyepieces
2.1 -- Rewritten in RealBASIC; various modifications to layout; first Classic and Linux versions
2.0.2 -- Bug fix (Export data file handles blank Barlow and RC fields properly)
2.0.1 -- Bug fix (Calculate button erroneously reset Barlow and RC buttons)
2.0 -- Scope Calculator 2, produced using Runtime Revolution
1.4 -- Final HyperCard-based version Scope Calculator

Bugs

I'm not aware of any, but if you find some, let me know!

Neale Monks, November 2008
http://homepage.mac.com/nmonks/