🔭 Astronomical Telescopes & Visual Optics
Telescope Magnification & FOV Calculator
Compute optical magnification ($M = \frac{f_{\text{scope}}}{f_{\text{eye}}}$), True Field of View ($\text{TFOV}$), exit pupil diameter, focal ratio ($f/\#$), and Dawes' limit resolving power.
🌌 8" Dobsonian ($D=203\text{mm}, f=1200$)
🪐 8" SCT ($D=203\text{mm}, f=2032$)
✨ 80mm ED APO ($D=80\text{mm}, f=600$)
🔭 130mm Reflector ($D=130\text{mm}, f=650$)
Optical Specifications
mm (8" = 203mm)
mm
mm
degrees (Plössl = 52°)
Optical Magnification (Power)
48.0× Power
Exit Pupil ($EP$)
4.23 mm
Focal Ratio ($f/\#$)
f/5.91
Dawes' Resolution
0.57 arcsec
💡 Field of View in the Night Sky:
A True FOV of 1.08° can fit approximately 2.1 Full Moons (Full Moon diameter ≈ 0.5°), ideal for wide-field open clusters and nebulae.
Telescope Optical Equations
Formulas governing visual astronomical observation:
- Magnification: $$M = \frac{f_{\text{telescope}}}{f_{\text{eyepiece}}}$$
- True Field of View (TFOV): $$\text{TFOV} = \frac{\text{AFOV}}{M}$$
- Exit Pupil Diameter: $$EP = \frac{D}{M} = \frac{f_{\text{eyepiece}}}{f/\#}$$ (Human pupil opens to $\sim 5 - 7\text{ mm}$ in darkness).
- Dawes' Limit Resolving Power: $$\theta = \frac{116}{D_{\text{mm}}} \text{ arcseconds}$$