1. What is Effective Focal Length?

Effective focal length describes the equivalent field of view a lens would have on a full-frame camera when used with a crop sensor camera. It helps photographers understand how their lenses will perform on different sensor sizes.

2. How Does the Calculator Work?

The calculator uses the effective focal length formula:

Where:

• \( \text{Focal Length} \) — The actual focal length of the lens (mm)
• \( \text{Crop Factor} \) — The sensor's crop factor (dimensionless)

Explanation: The crop factor multiplies the lens's actual focal length to show its equivalent field of view on a full-frame sensor.

3. Importance of Crop Factor

Details: Understanding crop factor is essential for photographers using multiple camera systems or comparing lenses across different sensor sizes.

4. Using the Calculator

Tips: Enter the lens's actual focal length in millimeters and the camera's crop factor. Common crop factors are 1.5 for APS-C (Nikon, Sony) and 1.6 for APS-C (Canon).

5. Frequently Asked Questions (FAQ)

Q1: Does crop factor affect image quality?
A: No, it only affects the field of view. The lens's optical properties remain unchanged.

Q2: What's the crop factor for Micro Four Thirds?
A: Micro Four Thirds cameras have a crop factor of 2.0.

Q3: Does effective focal length change aperture?
A: No, the lens's maximum aperture remains the same regardless of sensor size.

Q4: Why is full-frame considered the reference?
A: Full-frame (35mm) became the standard reference because it matches traditional 35mm film dimensions.

Q5: Can I use this for medium format cameras?
A: Yes, but note medium format crop factors are typically less than 1 (e.g., 0.79 for some Fuji GFX models).