is the number of degrees in one radian, used to convert the result from radians to degrees). 4. Visualizing the Concept

Use a calculator to plan 3-4 eyepieces that cover these FOV ranges:

A rising star in the community, Telescopius offers a highly detailed planner that combines FOV calculation with imaging opportunities based on your location and time of year. It is excellent for planning a night's imaging sequence.

Imagine driving two hours to a dark sky site to image the Pinwheel Galaxy (M101). You polar align, autofocus, and start capturing. After an hour, you check your images—the galaxy is a tiny speck in the middle of a sea of black. You have wasted a night because the focal length was too short.