If you’re new to Digital Single-Lens Reflex cameras or DSLRs then you might have heard something about “crop” factors or “film equivalents”. Not sure what it means? Well settle in and we’ll attempt to provide a basic overview of what that means in terms of everyday use.
Each of the large DSLR manufacturers (Canon, Nikon, Sony, Pentax etc) has many different camera models that they currently offer. Most of these models are referred to as APS-C sensor models. APS-C refers directy to the size of the sensor inside the camera. An APS-C sensor usually measures approximately 25.1 x 16.7 mm. Any camera with a sensor that is close to those dimensions is considered APS-C. This type of sensor is most common almong all DSLRs.
There is another larger sensor size frequently called “Full Frame.” This type of sensor measures 36x24mm and as you can see is quite a bit larger than an APS-C sensor. The reason this sensor type is called “Full Frame” is because it is the approximate digital equivalent of 35mm film. This sensor is much more expensive to manufacture than the smaller APS-C sensors and consequentially the cost of cameras with this type of sensor is much higher.
So if Full Frame sensors are the equivalent size of film what about the smaller (APS-C) sensors? An excellent question, APS-C sensors are smaller than the film equivalent so they inherrently have what is referred to as the crop factor. What is a crop factor? The crop factor can vary based on manufacturer but in its simplest terms it is an immediate crop and magnification of a smaller section of the picture frame.
Let’s look at a specific example. If you had a full frame camera and had mounted a 50-200 mm lens on it then no matter what focal length you chose within that range that would be the focal length you received. (I.e. if you zoomed to 130mm then your picture would be at 130mm). However with a Digital crop camera you would have to take that focal length and multiple it times your digital crop factor! So, a Canon Rebel has a digital crop factor of 1.6x. Taking the same example, if you zoomed the lens to 130mm multipled by your crop factor of 1.6x you would actually have an equivalent focal length of 208mm. Interesting? Yes, I thought so too.
Just for your reference here is the crop factor for most of the common DSLRs:
- Nikon: 1.5x
- Canon: 1.6x
- Pentax: 1.5x
- Sony: 1.5x
- Olympus: 2x
- Panasonic: 2X
A lot of lens manufacturers are now producing lens designed solely for digital crop cameras. These lens are optimized specifically for cropped cameras and will often not even be able to mount on a full frame camera. Sigma designates their crop lenses with the intials “DC” for digital crop. Canon titles theirs “EF-S”. Nikon calls theirs “DX” . If you currently own or are going to own a digital crop camera you might want to consider whether or not you believe you will ever own a full frame camera. If you think that at some point you might then I would recommend not purchasing lenses designed solely for digital crop cameras as they will not be compatable with full frame cameras later on down the road.
