Does Size Matter?

Let’s talk sizes, and whether your sensor size matters (and how it is going to affect your camera’s size and weight).

What is a full frame, and why is a certain size called “full,” given that there are much larger formats out there? It all comes down to history and what eventually became the de facto standard for 35 mm film: a 3:2 area of approximately 36 by 24 millimetres. When digital photography arrived, the major players in the industry decided to stick with the analogue standard to ensure that the lenses (and, as I suspect, the factory equipment) that worked well for film would continue to work well for digital cameras. However, the production cost of a full sensor has always been high, so different manufacturers introduced various crop factors over time to increase market penetration and keep shareholders happy. A smaller sensor also allows for a smaller and lighter camera body. If you make the sensor even smaller, you can put it in a phone, which has been the case since around 2000.

The bigger the sensor, the more light it receives, which improves low-light performance. A larger sensor also requires an appropriate lens to project a large enough image circle. If you use a lens designed for full frame on an APS-C or MFT body, the sensor will not be able to use the entire image circle because it is too small. This is where the crop factor becomes important. It tells you how much of the image your sensor actually captures. For example, if you use a 35 mm lens on a cropped body, the sensor only uses part of the projected image, resulting in a field of view similar to a 56 mm lens on a full-frame camera. And do not forget about the weight factor and the cost factor.

So what are the most common sensor formats a hobbyist is likely to encounter today?

• Full frame and APS. Crop factor is 1x.
• Different flavours of cropped formats (APS-C, APS-H, etc.). Canon’s APS-C size is 22.3 by 14.9 millimetres, which gives a 1.6x crop factor.
• Micro Four Thirds (MFT), used by Panasonic and Olympus. Crop factor is 2x.
• Even smaller sensors used for mobile food pornographyphotography.

A brief note on the number of pixels (picture elements, the tiny dots that colour the image on your screen or collect light on your camera sensor). When you see XYZ megapixels in a spec sheet, it has nothing to do with the physical size of the sensor. It refers only to the number of pixels the manufacturer managed to fit onto the sensor panel. Think of it as density.

Wikipedia has a very detailed article about the sensor formats and sizes; I would never dare to gain mastery over the enthusiastic community that’s always there for us.

The next station will be DSLR VS Mirrorless, and why I chose what I chose.