Focal Length Formula:
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Focal length is the distance between the lens and the image sensor when the subject is in focus, usually stated in millimeters (e.g., 28 mm, 50 mm, or 100 mm). It determines the angle of view and magnification of the scene being photographed.
The calculator uses the focal length formula:
Where:
Explanation: The formula calculates the lens focal length needed to achieve a specific field of view at a given working distance with a particular sensor size.
Details: Calculating focal length is crucial for selecting the right lens for specific photography needs, determining field of view, and planning camera setups for consistent imaging results.
Tips: Enter sensor size in millimeters, working distance in millimeters, and desired field of view in millimeters. All values must be positive numbers.
Q1: What's the difference between focal length and zoom?
A: Focal length is a fixed property of prime lenses, while zoom lenses offer variable focal lengths. A "zoom" refers to changing the focal length.
Q2: How does sensor size affect focal length?
A: Smaller sensors effectively increase the focal length (crop factor), while larger sensors provide a wider field of view for the same focal length.
Q3: What's considered a "normal" focal length?
A: A focal length approximately equal to the diagonal of the sensor (e.g., 50mm for full-frame) provides a natural perspective similar to human vision.
Q4: When would I need a longer focal length?
A: Longer focal lengths (telephoto) are used for distant subjects, wildlife photography, or when you need to isolate subjects from their background.
Q5: What about wide-angle lenses?
A: Shorter focal lengths (wide-angle) capture more of the scene and are ideal for landscapes, architecture, and tight spaces.