Understanding Camera Sensor Sizes for DSLRs

It has become a trend in today's modern society to own a DSLR (Digital Single Lense Reflex) camera and everyone raves on how many mega pixels they have on their latest camera, however more mega pixel doesn't necessarily mean better photos. One characteristice of digital cameras that many people ignore or are unaware of is the sensor sizes.

standard 35mm film

In the days of taking photographs using film it was fairly straight forward, the standard for consumer and prosumer cameras were the 35mm film. Which is basically the film that we used to load in our cameras before taking pictures at a birtday partys.


Today film has been replaced with digital sensors either a CMOS or CCD sensors. Now to make things are more complicated, these sensors come in different sizes and mega pixels. The reason being to either keep the price down or to have the camera smaller in size.

Overview

Lets have a look at the diagram above which we can now fully visualize the difference in sensor sizes of our cameras. To make it easier for everyone to relate to the diagram, we shall list the some of the cameras available in the market today and what sensor size do they have.

Full Frame Cameras 35mm equivalant

- Nikon D3, D3x, D700
- Canon 5D, 5D mark II
- Canon 1Ds, 1Ds Mark II, 1Ds Mark III
- Sony Alpha 900

APS-H (1.3x Crop)

• Canon 1D, 1D mark II, 1D Mark III

APS-C (1.5x Crop)

• Nikon D40, D40x, D60, D5000, D80, D90, D200, D300
• Sony A320, A230, A350, A300, A200, A700, A100
• Pentex K20D, K200D, K-7, K10D

APS-C (1.6x Crop)

• Canon EOS 1000D, 40D, 50D, 300D, 450D, 400D, 500D

Four Thirds System (2.0x Crop)

• Olyumpus range of cameras

1/2.5"

• This is just one of the sizes of used for compact cameras (point and shoot)

Crop Factor & Focal Length Multiplication
According to the diagram above we have listed down the crop factors of the different categories of sensors. Now to show the effects of crop factors we can look at the picture below

Full frame angle

Essentially crop factor describes the sensor's width ratio in reference to a full frame 35mm sensor. It is important to know and understand the crop factor of ones cameras as it effects the angel of a lense that you are using. This will now be a bit technical, bare with me here.

Lets say Leena just bought a Nikon D5000( 1.5x crop sensor) and attached a 50mm f1.8 lense to the camera. This means she is using the lense on a 1.5x crop factor lense which will produce the same field of view as a 1.5x50 = 75mm lense on a full frame sensor.

Remember the calculation for the next time you wish you invest in a new lense or camera. It might be confusing at first but once you talk to people or ask around things will be clearer.

Final Thoughts

The sensor size will also effect the quality of the picture, as smaller sensors tend to have more noise or grain. Just try taking a picture with 2 different cameras with the same mega pixels but different sensor size, you will notice that the camera with a larger sensor has less noise. Another way just use your camera phone and compare it to a DSLR or even a compact camera. This concludes the basic understanding of camera sensors sizes, hope it will be helpful.

If you want to learn more click on the links below:

http://en.wikipedia.org/wiki/Sensor_size
http://en.wikipedia.org/wiki/35_mm_equivalent_focal_length