Megapixels?

[EchoingWhisper]

Found something you may learn from. I've always thought that higher megapixels = more noise, but I realised I was wrong just a few weeks ago. DxOMark - More pixels offset noise!

 

[Garbz]

Nope you're still right, just reading the conclusions wrong. Effectively they are saying when you have a higher resolution then you can do some fancy maths to eliminate the noise when you resize the image to a smaller resolution. At that point you no longer have a high resolution.

The problem is the end result technically can only be worse. The SNR of a camera is determined by a large number of factors, but if you assume all electrical bits being equal then the signal to noise ratio is determined by the quantum efficiency of the photosite, which is the number of electrons moved for photons which hit the sensor. On a higher resolution camera this will always be lower simply because the pixels aren't a continuous surface. There are microscopic gaps between each pixel and that is an effective area which can't capture photons. So for all other things being equal you can get more signal to noise out of a sensor with a lower resolution for the same size simply because more of the sensor area is taking up by something that absorbs photons.

That said don't let theory get in the way of technical progress. I have no doubt the D800 will be vastly superior to my D200 despite the significantly smaller pixel dimensions.

 

[EchoingWhisper]

Nope you're still right, just reading the conclusions wrong. Effectively they are saying when you have a higher resolution then you can do some fancy maths to eliminate the noise when you resize the image to a smaller resolution. At that point you no longer have a high resolution.

The problem is the end result technically can only be worse. The SNR of a camera is determined by a large number of factors, but if you assume all electrical bits being equal then the signal to noise ratio is determined by the quantum efficiency of the photosite, which is the number of electrons moved for photons which hit the sensor. On a higher resolution camera this will always be lower simply because the pixels aren't a continuous surface. There are microscopic gaps between each pixel and that is an effective area which can't capture photons. So for all other things being equal you can get more signal to noise out of a sensor with a lower resolution for the same size simply because more of the sensor area is taking up by something that absorbs photons.

That said don't let theory get in the way of technical progress. I have no doubt the D800 will be vastly superior to my D200 despite the significantly smaller pixel dimensions.

It's kinda awesome how seeing how well the microlenses work. I remember seeing video illustrating how to light hits the microlens and lands on the photosite. I think a higher megapixel wouldn't matter anymore given that the technology of microlens is so good. But I also read from somewhere saying when the photosites reach to less than 2 microns, the microlenses will start to become less and less effective.