Calculators have data already in them. Some are examples from my telescope, a C11 SCT with 279.4 mm of aperture and 2,794 mm focal length at f/10.
Highlight the numbers already entered in the boxes and delete them and enter your own.
For large numbers, do not use commas.
1. Focal Ratio
1a. Aperture from Focal Length and Focal Ratio
2. Linear Diameter of the Airy Disk
3. Angular Diameter of the Airy Disk
4. FWHM Angular Diameter of the Airy Disk
5. FWHM Linear Diameter of the Airy Disk
6. Image Scale per Pixel
7. Focal Length and Focal Ratio Needed For Critical Sampling
8. Focal Length Needed for a Desired Image Sampling
9. Angular Size Based on Distance
10. Linear Size Based on Distance
11. Effective Focal Length from an Object's Size in an Image
12. Eyepiece Projection
13. Afocal Projection
14. Barlow (Negative Lens) Projection
15. Maximum Exposure Length for Planetary Rotation
16. Field of View
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