Understanding how cameras handle ISO and low light

- When you change ISO on your camera,…you gain the ability to use faster shutter speeds…and/or smaller apertures.…When ISO is set to a higher level,…your sensor seems to become more light sensitive,…meaning it doesn't need to be exposed to light…for as long to register an image.…In truth though your sensor…doesn't become more light sensitive…when you crank up the ISO setting.…Rather the camera is altering…one component deep in its guts.…While we call them digital cameras,…an image sensor actually outputs an analog signal.…That signal is passed through…an analog-to-digital converter after you shoot,…and that's where the digital part…of digital photography begins.…

Before that conversion process though,…that analog signals that comes off a sensor…has to be amplified.…The actual electrical impulses…that come off the sensor are very faint,…and without amplification they can't be easily measured…and then converted into numbers.…When you increase ISO, you're doing nothing more…than increasing that level of amplification.…