Understanding crop factor is essential for photographers who want to make informed decisions about lenses and camera bodies. Crop factor refers to how a camera sensor’s size affects the field of view compared to a traditional 35mm full-frame sensor.
What is Crop Factor?
Crop factor is a ratio that describes how much smaller (or larger) a camera’s sensor is compared to a full-frame sensor. The most common crop factors are:
- Full Frame (1.0x): Standard reference size (36mm x 24mm)
- APS-C (1.5x or 1.6x): Smaller sensor, common in many DSLRs and mirrorless cameras
- Micro Four Thirds (2.0x): Even smaller sensor, popular in compact and lightweight systems
How Crop Factor Affects Field of View
A lens mounted on a crop sensor camera will have a narrower field of view than the same lens on a full-frame camera. For example, a 50mm lens on an APS-C camera (1.5x crop) gives a field of view equivalent to a 75mm lens on full-frame.
Crop Factor Conversion Table
| Lens focal length | Full frame 1.0× | Nikon/Sony/Fujifilm APS-C 1.5× | Canon APS-C 1.6× | Micro Four Thirds 2× |
|---|---|---|---|---|
| 16mm | 16mm | 24mm | 25.6mm | 32mm |
| 24mm | 24mm | 36mm | 38.4mm | 48mm |
| 35mm | 35mm | 52.5mm | 56mm | 70mm |
| 50mm | 50mm | 75mm | 80mm | 100mm |
| 85mm | 85mm | 127.5mm | 136mm | 170mm |
| 200mm | 200mm | 300mm | 320mm | 400mm |
These figures compare field of view. Crop factor does not turn a 35mm lens into a physically longer lens.
Worked Example: 35mm on Two APS-C Systems
On a Nikon, Sony or Fujifilm APS-C camera, a 35mm lens gives a full-frame-equivalent field of view of 52.5mm: 35 × 1.5 = 52.5. On a Canon APS-C camera, the same lens is equivalent to 56mm: 35 × 1.6 = 56.
The lens remains 35mm in both cases. The Canon sensor’s slightly higher crop factor records a slightly narrower view, which is why identical focal lengths can frame differently across APS-C systems.
Impact on Depth of Field
Crop factor also influences depth of field. For the same aperture and framing, crop sensors produce a deeper depth of field compared to full-frame sensors, which can affect background blur and subject isolation.
Why Does Crop Factor Matter?
- Lens Selection: Understanding crop factor helps you choose the right lens for your desired composition.
- Focal Length Equivalence: It allows you to compare lenses across different systems.
- Creative Choices: Knowing how sensor size affects your images can help you achieve the look you want.
Conclusion
Whether you’re shooting landscapes, portraits, or wildlife, understanding crop factor will help you get the most out of your gear and make better creative decisions.