This effect is due to the nature of CCD (image) sensors which will produce bright, randomly placed spots if the shutter is held open to give a long exposure time. The visibility of these coloured dots also increases with temperature as well as exposure time.

Many digital cameras avoid this phenomenon by limiting the time that the shutter can stay open, for example to less than one second so that this noise does not become apparent, and forcing the use of flash.

The Coolpix 775 has an extended shutter speed range to allow such pictures to be taken without flash. This is in keeping with the Nikon philosophy of offering maximum flexibility to the photographer.

If the noise becomes objectionable, then the flash may, of course be employed or the camera can be cooled to reduce the exacerbating effects of raised temperature.

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