pixel density

On dpreview.com one of the specs they list for cameras is Pixel Density. When I do a side by side comparison of the D200 D300 and D700 their pixel density is 2.7 MP/cm² 3.3 MP/cm², and 1.4 MP/cm² respectively.

Is more or less better?

Is there an relationship between pixel density and noise? i.e. Why has the D700 got far better high ISO capabilities?

Is there any relationship between pixel density and depth of field? Why do smaller sensors have better dof?

Thanks for any help

Mary

On dpreview.com one of the specs they list for cameras is Pixel Density. When I do a side by side comparison of the D200 D300 and D700 their pixel density is 2.7 MP/cm² 3.3 MP/cm², and 1.4 MP/cm² respectively.

Is more or less better?

 

Is there an relationship between pixel density and noise? i.e. Why has the D700 got far better high ISO capabilities?

 

Is there any relationship between pixel density and depth of field? Why do smaller sensors have better dof?

 

Thanks for any help

 

Mary

There are many factors that affect the quality of image a particular sensor produces. Pixel density gives you an idea of how closely packed the photosites on a sensor are. In general, a lower pixel density is better (but not always as there are other factors that affect sensor quality). With more space between the centre of adjacent pixels means each pixel can be bigger - which can result in better high ISO performance.

I assume when you say "better" DOF you are really referring to "larger" DOF. Larger DOF is only better if that's what you require for the type of shots you're doing. In actuality, sensor size has nothing to do with DOF. The reason why you tend to get larger DOF with a smaller sensor is because you tend to use shorter focal lengths to achieve the same angle of view as compared to a larger sensor, which would require a correspondingly longer focal length. It is the use of shorter focal lengths that gives you this difference in DOF.

Thanks Warren,

You have answered everything for me

Mary