What is Equivalent Aperture and Why Should You Care?
Have you ever wondered how to compare lenses across different camera systems? That's where Equivalent Aperture comes into play. It's a nifty concept that helps you understand how a lens will behave on cameras with different sensor sizes.
Why should you care? Knowing the Equivalent Aperture can save you from buyer's remorse when you're shopping for lenses. It gives you a clearer picture of what your lens can do on various cameras, making your investment worthwhile.
How to Calculate Equivalent Aperture
The calculation isn't rocket science. The formula is straightforward:
[\text{Equivalent Focal Length} = \text{Focal Length (mm)} \times \text{Crop Factor}]
Where:
- Focal Length (mm) is the distance between the lens and the image sensor when the subject is in focus
- Crop Factor is a number that compares the sensor size of a camera to a 35mm film frame
Steps to Calculate
- Determine the Focal Length (mm): Find out the focal length of your lens. It's usually engraved on the lens itself.
- Determine the Crop Factor: Refer to your camera's manual or a quick online search. Full-frame cameras have a crop factor of 1, while crop-sensor cameras will usually have a number greater than 1.
- Apply the Formula: Multiply the focal length by the crop factor.
Calculation Example
Suppose you have the following variables:
- Focal Length (mm): 50 mm
- Crop Factor: 1.5
Plugging these into the formula:
[\text{Equivalent Focal Length} = 50 \times 1.5 = 75 \text{ mm}]
Your 50mm lens on a crop sensor camera will behave like a 75mm lens on a full-frame camera in terms of field of view.
Common Crop Factors
| Camera Type | Crop Factor |
|---|---|
| Full-Frame | 1.0 |
| APS-C (Canon) | 1.6 |
| APS-C (Nikon, Sony) | 1.5 |
| Micro Four Thirds | 2.0 |