AC130: Sensor blur

[JJCA]

I couldn't seem to understand this: 3x 1/3-type progressive 2.2 MP CMOS (in ac130)

What does this generally mean? esp those MPs? thanks! Cause if it's a 2.2 mp per chip and has 3 chips, does that mean the camera only has 6.6mp in total?

 

[Mike Warren]

It has 3 sensors, 1 for red, 1 for blue and one for green. Each sensor is 2MP which maps 1:1 to the size of a 1920 x 1080 image. Technically, there are 6MP, but because they map on top of each other there are only 2MP seen. How they do this is by having a prism and filters that send the appropriate colours to each sensor. Sounds to me that you are coming from DSLRs which use a different system. In DSLRs what's called a Bayer pattern is used where each final pixel is made up from 4 pixels that are adjacent to each outer. With a Bayer sensor, the brightness of the image is taken from all the pixels, but the colour is taken from a group of 4 pixels. This results in much lower colour resolution than brightness (luminance) resolution.

Having more than 2MP means the image must be scaled down to 2MP and this is generally done by simply not reading some pixels and can cause "jaggies" and moire. This is not a major issue in cameras like the AC130 as the optical low pass filter is designed specifically to match the final output resolution of 2MP.

So, simply put, having "only" 2MP is actually a good thing for a HD (1920 x 1080) video camera.

 

[JJCA]

Oh, now that's quite an explanation. Thanks for the info Mike. I'm having a lot of considerations on what camera I have to buy so that I could effectively cover events such as weddings, concerts, etc. Thanks again!