Recording Pixels, sensor size, and pixel count.

[olenzekm]

I have a general question about how sensor size relates to pixel count and pixel size.

I have an 8 MegaPixel Canon A720. I realize that it has a small sensor size. I am willing to accept that because I want a small shirt-pocket camera.

I do not really need to take pictures with the 8 MP resolution. This camera is capable of producing images at lower pixel recording levels such as 5 MP. That level is adequate for me.

My question is: is there any advantage, other than the memory consumed by the image, to shooting 5 MP pictures in a camera that is capable of 8 MP rather than shooting the full 8 MP?

In other words will shooting at 5 MP result in the effective sensor area for each “pixel” being larger than the effective sensor area for each pixel when shooting at 8 MP? Or are some of the pixels on the sensor simply ignored to record the image at a lower MP level thereby simply wasting the extra pixels?

Thank You,
Marc.

[griptape]

Don't take this as gospel, but from everything I've read, the pixel size itself stays the same regardless of the resolution you set the camera at. So each pixel well will receive the same amount of light, and the pixels themselves will be the same size, there will just be fewer of them.

[David Metsky]

The camera has to take the full 8MP image, and then via the loigc chip decide how to turn it into a 5MP image. That involves merging and throwing away data. Now, the 5 MP image may be less noisy, but only because it's smaller and some of the noise got removed while getting rid of the extra pixels.

Some newer cameras give you a faster FPS in burst mode with smaller image size, but not the A720. So, there's no real reason to drop the image size except for making your life easier so you don't have to do that step by yourself if you're looking for a 5MP image in the end.

Personally, I always shoot at maximum image size.

[fotogmarc]

A few years ago I tried testing this theory. I shot photos at the camera's full resolution and then half and compared the 2. I did not notice any difference in image quality at the time. Of course this was 2 yrs ago and technology may have changed.
I always go full res. unless I'm short on memory or know ahead of time these will not be larger prints.