<P> Nearly all camera phones use CMOS image sensors, due to largely reduced power consumption compared to CCD type cameras, which are also used, but in few camera phones . Some of camera phones even use more expensive Backside Illuminated CMOS which uses energy lesser than CMOS, although more expensive than CMOS and CCD . </P> <P> As camera phone technology has progressed over the years, the lens design has evolved from a simple double Gauss or Cooke triplet to many molded plastic aspheric lens elements made with varying dispersion and refractive indexes . The latest generation of phone cameras also apply distortion (optics), vignetting, and various optical aberration corrections to the image before it is compressed into a . jpeg format .' </P> <P> Most camera phones have a digital zoom feature . A few have optical zoom . An external camera can be added, coupled wirelessly to the phone by Wi - Fi . They are compatible with most smartphones . </P> <P> Images are usually saved in the JPEG file format, except for some high - end camera phones which have also RAW feature and the Android 5.0 Lollipop has facility of it . Windows Phones can be configured to operate as a camera even if the phone is asleep . An external flash can be employed, to improve performance . </P>

When did cell phones become available to the general public