Crop factor is one aspect of digital cameras that can confuse beginner photographers. Because so many cameras and lenses are flooding the interchangeable lens market these days, the compatibility and suitability of your photography equipment are critical considerations.
Whether your camera uses a Full-Frame sensor, an APS-C sensor, or something even smaller will sometimes affect which lenses can be mounted on it and what field of view a particular lens will provide.
In this guide:
- Commonly asked questions about crop factor
- Understanding sensor size
- What is focal length?
- How does sensor size affect focal length?
- Real world implications
- Working out the equivalent focal length
- Choosing your lens
Commonly Asked Questions About Crop Factor
Crop factors can significantly impact which lenses work with which cameras. The most commonly asked questions about crop factors are:
- Is this lens compatible with my current camera?
- How will my camera's smaller sensor affect the lens's focal length?
To help you understand digital camera crop factor, we first need to explain camera sensors and the sizes available.
Understanding Sensor Size
One of the essential things to understand about crop factors is that the figures provided are based on the standard size of a full-frame sensor, which matches the width of a piece of 35mm film — measuring 36mm x 24mm.
In addition to 35mm film, medium and large format film stocks offer finer grain, better tonal range, deeper exposure latitude, and greater control over focus and depth of field.
As digital cameras entered the market in the late 20th century, entry-level DSLRs and mirrorless cameras featured smaller sensors, such as the standard APS-C size (15.6 x 23.5mm) or the Canon APS-C variant (14.8 x 22.2mm).
The Canon EOS R and its Full-Frame sensor
The difference in size between sensor formats can significantly impact the portion of a scene captured and the overall image quality. Crop sensors capture a smaller portion of the scene than full-frame sensors — which brings us to focal length, another key consideration for lens compatibility.
What Is Focal Length?
Focal length is the distance between your lens and the camera's image sensor when your subject is in focus. It determines the angle of view — how much of a scene is captured. A shorter focal length produces a wider angle of view, while a longer focal length narrows the field of view and brings distant subjects closer.
How Does Sensor Size Affect Focal Length?
The Canon EOS 7D Mark II and its APS-C sensor
In the film era, SLR cameras used 35mm film universally — meaning any lens at a given focal length produced the same field of view regardless of the camera body. With the introduction of smaller digital sensors, crop factor became a relevant consideration. When a lens designed for full-frame is mounted on an APS-C camera, it produces a narrower field of view than it would on a full-frame body.
What Are the Real World Implications?
If you were to take the same photo on a full-frame camera and a crop sensor camera using the same lens, the results would immediately reveal the real-world implications of crop factor. The difference in effective focal length and field of view can also impact depth of field and subject isolation.
Working Out the Equivalent Focal Length of a Lens
The crop factor multiplier varies depending on your camera system. Here are the common crop factors by mount:
1.5x crop factor
- Nikon DX (APS-C)
- Sony E-Mount (APS-C)
- Pentax DA
- Fujifilm XF
1.6x crop factor
- Canon EF-S
- Canon RF-S (Canon's current APS-C mirrorless format, replacing the discontinued EF-M system)
2x crop factor (Micro Four Thirds)
- OM System (formerly Olympus) OM-D Series
- Panasonic Lumix G Series
2.7x crop factor
- Nikon CX
- Sony RX
Based on the above, mounting a 50mm lens on a Nikon DX camera gives you an equivalent focal length of 75mm (50mm × 1.5 = 75mm) — the same field of view you'd get from a 75mm lens on a full-frame camera.
For more information on choosing the right lens, explore our photography tips blog.
Choosing Your Lens
To address the effect of crop factor, most camera manufacturers produce lenses specifically designed for their smaller-format cameras, as well as full-frame compatible options.
Generally, full-frame lenses will work on smaller-sensor cameras, though the crop factor will apply. Lenses designed specifically for smaller sensors, however, will not perform correctly on full-frame cameras — typically resulting in vignetting or automatic sensor cropping.
In the Micro Four Thirds system from OM System and Panasonic, lenses are designed with focal lengths that reflect the 2x crop factor. For example, the OM System 45mm f/1.8 lens delivers a portrait-friendly 90mm equivalent when mounted on a compatible camera.
Find the Best Camera Kit for You
At Ted's Cameras, we offer a wide range of camera gear to help you capture the best images possible. If any of this is still a bit confusing, our in-store experts across our nationwide Ted's Cameras stores are always happy to help you choose the right lens for your camera system.