DSLR Camera -Manual Mode Operation Part 1: ISO what is it?

ISO is what we know as the sensitivity of a digital camera. Digital camera comes with two kinds of sensors, namely,CCD or CMOS. By changing ISO setting, you can change the sensitivity of the sensor.

Take the following photo set for example. You can see that the darkest of the lot was taken with an ISO setting of 200 and then gradually it was increased from 200 to 400, 800, 1600 and then finally to 3200.

You can see how keeping light condition, F-STOP (Aperture) and Shutter Speed same, the photo changes just with an increase in sensitivity. From the above photo set, you will find the picture with best quality was actually taken with ISO setting between 400 and 800. 200 is too dark and 1600 and 3200 reflect too much light. With higher ISO even the slightest of light is captured in the sensor. The lower the ISO, the more robust is the photo but lower settings are not recommended for high shutter speed and low light conditions. High ISO settings are good for capturing the best shot of moving objects and night photography though it requires a steady hand (Preferably use a tripod). However, photos captured with high ISO settings in day light conditions usually come grainy.