The Difference Between A Full Frame Sensor And An APS-C "Crop" Sensor DSLR Camera

What exactly is a crop sensor camera? Well, a full frame 35mm camera (film or digital) takes a picture that is around 36mm x 24mm in size. When digital sensors were first introduced it was not possible to make a digital sensor that large in any quantity. The ones that could be made were so expensive that no one would have been able to afford a camera that used one. Camera makers decided to make a smaller sensor that was around 15mm x 22.5mm which just happened to be close to the image size of the (short-lived) APS film format. The reason that we call them "crop" is because if you take a full frame image and crop the center 15mm x 22.5mm out of it you get an imager the size or the "crop" sensor.

So what does all of this technical mumbo-jumbo mean for the average photographer? Not a whole lot! For the average user a "crop" sensor camera will provide you with just as high quality pictures as a full format camera, just put your kit lens on it and enjoy shooting pictures. For people that want to learn more read on. Other than the obvious difference in image size the only other difference between the two sensors is the angle of view. Because the APS-C sensor is smaller is has a smaller angle of view than the full frame sensor has. This smaller angle of view creates a something called a "digital multiplier". The digital multiplier is 1.6x for Canon EOS DSLR cameras and 1.5x for Nikon, Pentax, and Sony DSLR cameras. This digital multiplier can work in you favor or it can work against you if you don't understand it. So all this to tell you that if you need a wide angle lens of around 16mm on a full frame camera you will need around a 10mm lens on an APS-C sensor camera to achieve that same wide angle. However, if you need a zoom of around 450mm you only need to buy a 300mm lens for the APS-C sensor camera. So to put it simply...

For Canon EOS cameras:

• APS-C sensor focal length to equal field of view of full frame focal length you multiply by 1.6
• Full frame focal length to equal field of view for APS-C sensor you divide by 1.6
  

For Nikon, Pentax, and Sony cameras:

• APS-C sensor focal length to equal field of view of full frame focal length you multiply by 1.5
  
• Full frame focal length to equal field of view for APS-C sensor you divide by 1.5

Also note that the aperture stays constant because there is no digital multiplier for lens speed. To find out more information on this topic including more technical data than you can throw a stick at please visit www.bobatkins.com.