Understanding Digital Camera Crop Factor

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 is a Full-Frame Camera, APS-C format camera, or even smaller will sometimes affect what lenses can be mounted on the camera and also what field of view a particular lens will provide.

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 have 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 is the same width as a piece of 35mm film, which measures 36mm x 24mm.

In addition to 35mm film stock, medium and large format film stocks also offer finer film grain, better tonal range, deeper exposure, and greater control over focus and depth of field.

As digital cameras entered the market in the late 20th century, entry-level DSLRs and newer Mirrorless cameras featured smaller-sized sensors, such as the standard APS-C sized 15.6 x 23.5mm sensor or the Canon crop-sensor variant (14.8 x 22.2mm).

The difference in size between the film stocks and camera sensors can significantly impact the size and quality of the image you capture. Crop sensors capture a much smaller portion than full-frame sensors.

Then there's the focal length, another consideration for the compatibility and suitability of your photography accessories and equipment.

What Is Focal Length?

Focal length is the distance between your lens and the camera's image sensor when your subject is in focus.

The focal length determines the angle of view or how much of an image is captured. A lens with a smaller focal length will have a wider angle of view than a lens with a longer focal length that captures more.

How Does Sensor Size Affect Focal Length?

In the pre-digital age of film photography, SLR cameras used 35mm film, which meant that as long as the lens's focal length remained the same, any camera would capture the same field of view.

It wasn't until the advent of digital photography and the introduction of smaller image sensors that the issue of crop factor was born.

When mounted on an APS-C camera, the same lens will provide a narrower field of view than a Full-Frame camera.

What Are The Real World Implications?

If you were to take the same photo on a full-frame camera and a crop sensor camera, the results would immediately reveal the real-world implications of crop factors. The difference in focal length and field of view can significantly impact other aspects of photography, like depth of field.

Working out the equivalent focal length of a lens

The formula for working out the crop factor of your camera based on its sensor size uses Pythagorean Theorem. So to avoid a math lesson, you can use the following crop factors depending on your chosen lens type and brand.

Camera Lenses with a 1.5x Crop Factor

• Nikon DX
• Sony E-Mount
• Pentax DA
• Fujifilm XF

Camera Lenses with a 1.6x Crop Factor

• Canon EF-S
• Canon EF-M

Camera Lenses with a 2x Crop Factor (Micro Four Thirds)

• Olympus OM-D Series
• Panasonic DMC Series

Camera Lenses with a 2.7x Crop Factor

• Nikon CX
• Sony RX
• Samsung NX Mini

Based on the above information, you can work out that mounting a 50mm lens on a Nikon DX camera will provide you with the equivalent focal length of 75mm. (50mm X 1.5 = 75mm).

This setup would provide you with the same field of view as if you mounted a 75mm lens to a full-frame camera.

Check out our camera lens buying guide for more information on choosing the right lens.

Choosing your lens

To combat the effect of crop factor, some camera manufacturers have produced specific lenses specifically designed for use on their smaller-format cameras and others for full-frame models.

Generally, full-frame compatible lenses will work on smaller-sensor cameras as well. Unfortunately, lenses designed for smaller sensors will not work on full-frame cameras and will typically result in image aberrations, including vignetting or automatic cropping of the camera's sensor.

In other cases, such as the Micro Four Thirds range from Olympus and Panasonic, lenses have been created with focal lengths that reflect their smaller sensor. An example is the Olympus 45mm f1.8mm lens providing a portrait-friendly 90mm equivalent when mounted on compatible cameras.

Shop some of our top lenses here

Find the best camera kit for you

At Ted's Cameras, we offer the best camera gear to help you capture the best photos possible. If all of this technical information is a bit confusing, don't forget that you can talk to our experts at our nationwide Ted's Cameras stores. They will help you pick the best lens for your full-frame or APS-C camera.