Pixels and Micro Lenses

CCDs,  Micro Lenses and Microns

By Jon Gilbert,  Phase One US

Micro Lenses,

Phase One uses two main types of CCD:  ones with micro lenses and ones without micro lenses.  Micro lenses are just as they sound; tiny lenses that sit atop each pixel.  They focus the light on the center of the pixel well, giving the back an extra stop of light.  The downside of traditional micro lenses is that when light hits them at sharp angles, they can cause the image to have a color cast.  This makes them unsuitable for technical cameras using very wide lenses or swings and tilts.  In this situation, generally a CCD without micro lenses will perform better.  The P65+ , however,  breaks all the traditional rules by implementing a new micro lens design with more symmetrical pixels.  The end result is a CCD that is more uniform and even less prone to lens cast than non-micro lens CCDs.

Microns,

The old concept that larger pixels yield better results has not exactly held true in practicality, as resolutions get higher and higher pixels get smaller.  The P25+ has 9 micron pixels,  the P45+ has 6.8 micron pixels, and finally the P65+ has 6 micron pixels.  Despite the fact that pixels have gotten smaller, better development has made the smaller pixels more efficient, and we actually see better results from the newer CCD.  Smaller pixels are also less prone to moire and offer better image handling at long exposures.

* While the P40+/P65+ have micro lenses, they do not have the same wide angle limitations of older micro lens CCDs.