Telescope Field of View Calculator 35mm

Field of View Formula:

\[ \text{FOV} = 2 \times \arctan\left(\frac{36}{2 \times f}\right) \]

Horizontal Field of View:

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1. What is Field of View?

Field of View (FOV) is the extent of the observable world seen through a telescope or camera at any given moment. For 35mm format, it's calculated based on the 36mm width of the film/sensor.

2. How Does the Calculator Work?

The calculator uses the FOV formula for 35mm format:

\[ \text{FOV} = 2 \times \arctan\left(\frac{36}{2 \times f}\right) \]

Where:

\( f \) — Focal length of the telescope (mm)
36 — Width of 35mm film/sensor (mm)

Explanation: The formula calculates the angular width of the scene that will fit across the frame based on the telescope's focal length.

3. Importance of FOV Calculation

Details: Knowing your FOV helps in planning astronomical observations, understanding what will fit in your frame, and comparing different telescope setups.

4. Using the Calculator

Tips: Enter the telescope's focal length in millimeters. The result will be the horizontal field of view in degrees for a 35mm format camera.

5. Frequently Asked Questions (FAQ)

Q1: Why use 35mm format for calculations?
A: 35mm is a standard reference format that makes it easy to compare different optical systems.

Q2: How does sensor size affect actual FOV?
A: Smaller sensors will have a narrower FOV with the same telescope, while larger sensors will show more of the image circle.

Q3: What's a typical FOV for telescopes?
A: Wide-field telescopes might show 3-5°, while planetary telescopes often have FOV under 1°.

Q4: Does eye relief affect apparent FOV?
A: This calculator shows true optical FOV. Apparent FOV in eyepieces depends on their design.

Q5: Can I calculate vertical FOV too?
A: Yes, using 24mm instead of 36mm in the formula (for 35mm format's 24mm height).