Focal Length Multiplier Calculator

How to Use This Calculator

1. Enter the original focal length of your lens in millimeters (mm).
2. Enter the multiplier value of your teleconverter or extender. This is usually printed on the device itself (e.g., 1.4x, 1.5x, 2x).
3. Click the "Calculate" button to see the effective focal length and field of view reduction.
4. For example, if you have a 50mm lens and a 1.4x teleconverter, the effective focal length would be 70mm, and the field of view would be reduced by 40%.

Understanding Focal Length Multipliers

A focal length multiplier is a value that, when multiplied by a lens's actual focal length, gives you the equivalent focal length in terms of field of view. This is particularly useful when using teleconverters or extenders on camera lenses.

Common Applications

• Teleconverters: Allow you to shoot distant subjects with a longer effective focal length than your lens actually provides.
• Extenders: Increase the maximum magnification possible with telephoto lenses, though at the cost of light loss.
• Comparing Lens Performance: Help you understand how different lenses will perform with various accessories.

Important Notes

Using teleconverters or extenders reduces the amount of light reaching your sensor, which may require adjusting your camera's exposure settings. Additionally, the effective aperture (f-number) is also reduced by the same multiplier, further affecting exposure.