What is a Crop factor? Full frame and Crop sensors.

Due to fact that I love shooting landscapes, I am in love of the new Canon 5D Mark II. Talking a lot about it a friend asked me what’s that special with this camera compared to my Canon 40D. And it all came to one major difference: the 5D Mark II has a full frame sensor and the 40D has a crop sensor. So in this article I will try to explain the “Crop factor” notion, and the difference between them.

Full frame notion. A full frame sensor has an area of 36 x 24 mm and it’s close to the area of a 35mm film camera, back in the film days.

Crop factor. Well many of the digital cameras, from compact to DSLR cameras, have different image sensors with different dimensions. Most of the sensors have sizes equal or smaller than 36 x 24 mm. Because of the smaller sensor, the camera tends to capture less than an image giving the effect of cropping. There are a lot of crop factors starting from 1x (the Full Frame) and going all the way to 2x (Olympus), for DSLR’s and going even further than 6x for compact cameras. A 2x crop factor refers to a sensor size 2 times smaller than the full frame meaning a roughly 18 x 12 mm sensor size.

Now let’s see how this translates in the actual size of the image:

Here’s an image with different crop sizes from the whole crop factor range from Canon and Nikon (Canon has Full Frame, 1.3x and 1.6x sensors and Nikon has Full Frame and 1.5x sensors) marked with rectangles with different colours:

• Full Frame
• 1.3x Crop Factor
• 1.5x Crop Factor
• 1.6x Crop Factor

This factors translates into the focal lengths as well. For example, this photograph was taken with a full frame camera with a focal length of 40mm, but if you put the same lens on a camera with 1.3x crop factor and adjust it to the same focal length value, you will obtain an image similar to an image taken with a full frame camera with a lens having a 50mm focal length (40 * 1.3 = 52).

Now that you understand these notions, keep in mind that this it’s an important factor in choosing cameras.

Full frame (FF) vs Crop cameras (CF):

• FF with the same lens gives an wider view that CF. So FF cameras are better in landscapes, architecture, and situations where you don’t have a lot of space to move around to fill the frame with the subject. But, CF cameras are better in sports, bird photography, etc. because of that crop factor which gives a little extra zoom (increasing a 400mm focal length to 640mm 0n 1.6x).
• FF have better control on the noise at high ISO. This is because of the large sensor on which the photo sensitive cells aren’t as crowded as on the smaller sensor of the crop camera.
• CF are less expensive than FF
• Many manufacturers designed special glass for the CF that are lighter and can’t be used by FF because it causes massive vignetting.

Choosing which is right for you. Taking into considerantion all the information above, landscape, arhitecture and wedding photographers might find a Full Frame camera very usefull. On the other side, nature, wildlife, sports and even war photographers will choose a crop camera due to extra boost in zooming in without loosing details.

Tags: Camera Gear, Canon, Comparation, DSLR, Nikon, Photography