In this activity, we look at how our camera uses metering to gain correct exposure. The first is Multi/ Evaluative/ Matrix depending on your brand of camera. This mode looks at the whole scene and finds the best average between the highlights and shadows and works out what settings would suit the whole frame, or if it recognises a face or a point of interest or focus it may lean towards the best settings for that subject. Next is Centre-weighted. Centre-weighted metering is split into two zones, an outer zone of around 40% of the frame that is considered in the metering but not as much as the “Primary Zone” in the centre of the frame that takes up 60% of the frame and most of the metering weight. This mode is good for portraits and images where the centre is the main focus of the scene. Finally, we have spot metering. Spot metering is based on a tiny spot in the frame/scene, typically in the centre of the frame for most cameras, some more advanced cameras will let you move the spot manually where you want it in the frame. This determines a proper exposure for that specific spot, not the average of the whole frame. As pictured above, some cameras vary in modes. Now in saying that, cameras are set to expose for 18% grey, so scenes that are mostly white or mostly black will trick your camera. So if you point your camera at something mostly white, say, snow or a white dress, the camera meter will underexpose the image because it is trying to make the image grey. For very dark subjects, say, black backdrop, a heavy shadow, a black dress or a black dog, the camera will overexpose the image to do the same, make the image grey. You can use an 18% grey card to establish correct exposure by shooting in manual mode and keeping settings at your control. Put the card in the same light as your main subject and fill as much of the frame as you can. If your card is small, this is where “Spot Metering” is handy. Adjust your settings as needed, aperture, shutter speed and ISO to gain a correct exposure then proceed to shoot your subject with the settings of the card.
Here below are images of a white T-shirt from +3 exposure compensation down to -3 exposure compensation.
The exposure compensation of +1 here I feel gives a better representation and exposure of what I could see with my own eye with the lighting I used. So for the lighting, I used a warm work light from Bunnings and bounced it off the wall behind the subject. I have then repeated the same but with a black T-shirt. Below are the images of the black T-shirt from +3 down to -3 exposure compensation.
The exposure compensation of -1 is the better exposure of this set, however, I feel an exposure somewhere between -1 and -2 would have been best suited. I never really took in to account the metering process and the 18% grey before doing this activity and that my camera will under or overexpose depending on what it was metering off. I always tried to get it to the best exposure the camera was displaying on the exposure meter. With this new knowledge under my belt, I hopefully can say goodbye to over or underexposed images or at least hello to better exposed images :p
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