A good FOV calculator solves all of this by computing two critical numbers: and Apparent Field of View (AFOV) .
In the digital age of astrophotography, guessing is no longer an option. Whether you are a beginner with a Dobsonian or a seasoned astrophotographer using a Planewave telescope, the is the top tool you need before you even step outside. But not all calculators are created equal.
You don’t need to memorize the formulas, but understanding them helps you use calculators better.
Stellarium is a powerful, free open-source planetarium software. It includes a built-in "Oculars" plugin that allows for incredibly accurate FOV simulation. astro fov calculator top
) will look with your specific setup. It also shows the resolution ( 2. Stellarium (Desktop & Web Versions)
This article dives deep into why an astro FOV calculator is the top resource for visual astronomers and photographers, how to use one correctly, and a comparison of the top 3 tools dominating the market in 2024.
A 0.5× reducer doubles your FOV; a 2× Barlow halves it. Always include these in your calculations. A good FOV calculator solves all of this
While the calculators do the work for you, understanding the underlying math provides valuable insight.
FOV (degrees)=(Sensor Dimension (mm)Focal Length (mm))×57.3FOV (degrees) equals open paren the fraction with numerator Sensor Dimension (mm) and denominator Focal Length (mm) end-fraction close paren cross 57.3 Note: 57.3 is an approximation of a radian in degrees ( The Pixel Scale Formula
The actual, physical angle of the sky visible through your telescope. But not all calculators are created equal
Calculate how many panels you need for ultra-wide targets.
The ultimate guide to choosing and using the top astrophotography field of view (FOV) calculators to perfectly frame your deep-sky images.
Telescope Focal LengthEyepiece Focal Lengththe fraction with numerator Telescope Focal Length and denominator Eyepiece Focal Length end-fraction Conclusion