6 January 2012

Meter down

Thanks to my friend Rahul Purbey, an avid enthusiast, I got a new topic to write on - Metering. Due to his persistent queries, I had to do quite a bit of research on the topic and I think I have answer to his root query - "what is camera metering?".

Image Courtesy: my3boybarians.com
Camera metering is the funda that comes into picture once you have chosen the ISO, shutter speed and aperture. These three determine the exposure levels of the captured image - how under/over/correctly exposed the image is.

Metering can be inbuilt (most of us use the camera's inbuilt metering system) or external (the ones we see on tv, used in photoshoots wherein a person holds a metering device infront of the model's face to measure light). I am talking about the inbuilt metering system here.

Once you push down the shutter button and wait for the camera to focus on the subject, the camera performs the metering function and shows results on the lcd screen. The result is displayed by different models/manufacturers differently. In the above image, the metering result is shown along a horizontal scale (circled in red) with the center of the scale being perfect exposure (according to the camera's metering algorithm; camera metering is not always accurate) and either side being over and under exposure.

In the above image, it shows that the image is heavily underexposed(the meter shows readings on the -ve side of the graph) and hence, your image will be very dark if you use the current ISO+shutterspeed+aperture combination.

There are different ways in which your camera performs metering. The usual modes are spot metering, center-weighted and matrix/evaluative metering. Spot metering uses a spot on the frame to perform the metering process and determining whether that spot will be overexposed or underexposed. Center weighted metering, as the name hints, uses a small area around the center of the frame to perform metering. Matrix metering uses many more points spread out around the frame to perform metering.

So if you are concerned only about the rose in the frame and don't care if other elements in the frame get over/under exposed, use spot metering, and so on.

Its nice to put your grey cells to work while clicking a photo. Know the shutter speed, ISO and aperture settings and what exposures typical combinations provide. Also look at the meter before clicking. Look at it as a challenge - don't be a point and shoot user. Once you ready yourself for these challenges, you will actually enjoy and recommend photography as a hobby, instead of branding it as a piece of cake.

Happy clickin!

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