Few key concepts in Photography

  1. DoF (Depth of Field)
  2. Exposure
  3. Aperture
  4. Focal Length
  5. Shutter Speed
  6. ISO
  7. White Balance

DoF – Area covered from the object in focus (subject) and the farthest point in the background (infinity in case of landscape, a wall or a door frame in case of portraits etc.,)

Exposure – the amount of light that is allowed to enter through the lens on to the sensor (or film). Cameras come with compensation controls which let you manually override the exposure derived automatically by the camera. Usually done in thirds stop (1.0, 0.7, 0.3, 0.0, -0.3, -0.7, -1.0 etc) upto 6 stops either side of camera’s calculated exposure (0.0)

Aperture – the opening in the camera through which light enters and falls on the sensor (or film). Bigger the diameter, more is the area covered in the photo. Not same as exposure.. bigger diameter means more light and more light, meaning blowing up if the type of light is harsh, for example midday sun or shooting directly into the sun.. expressed in f numbers… higher the f number smaller the diameter of the aperture at the moment of shutter release.

Focal Length – expressed in ‘mm’ . Depends on the lens. a 55 – 300 mm lens means the minimal focal length of 55 mm and maximum focual length of 300 mm. Not clear how its related to zoom factor… need to look up.

Shutter Speed – expressed in seconds or fractions of second. Faster the shutter speed, lesser is the duration the light allowed inside the camera to the sensor.

ISO – Image quality expressed in whole numbers. Generally digital cameras today have a base ISO of 100 and can go upto any extent (max boosted ISO today is 105000 odd in D5100). Higher the ISO, more grainy the picture captured. Used in low light conditions to boost up the sensor’s sensitivity to light when used with higher shutter speeds. If possible, ISO should be maitained low with lower shutter speeds in low light conditions (which may mean blurred images in case of hand held shots.. use tripod in such cases).

White Balance – The type of light that defines the ambience.. like Sunny, cloudy, room lighting (tungsten), flash lighting etc., Depending on the setting, camera compensates one of RGB color channels to bring natural colors. For example, with room lighting WB, shooting a landscape will render a bluish image, since room lighting (tube lights, tungsten filament bulbs etc.,) have less B channel (blue color) or rather boosted up R and G channels. So camera compensates automatically by boosting up the B channel to equalize with R and G. But since we are shooting outdoors where there is a better balance of RGB channels, additional boost to the B channel makes the photo bluish (sometimes produces dramatic images though…)

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