So last week we began discussing shutter speed. If you're anything like I was when I first started learning this stuff I just thought I had the concept of Aperture under control when people started throwing Shutter Speed and ISO at me. My head started spinning all over again. How was I ever going to figure this exposure thing out if all three of these depend on each other and on conditions beyond my control to make a proper exposure?
Never fear! Once we have explored these three variables (aperture, shutter speed, and ISO) seperately, I will show you some of the tricks of how I learnt to understand their relationship to each other when trying to create a properly exposed image.
Getting back to shutter speed and lighting. Let's start with a practical exercise. Remember back in January I gave you the exercise of opening and closing your eyes at different speeds to understand depth of field? We're going to try a different version of the exercise by changing a variable. This time each time we open our eyes we are going to count how many seconds it takes before we are able to focus on the items around us. The variable - lighting. Start out in a room where you are able to control the lighting. Close all the blinds, curtains, and door to prevent interference from external light sources. Start by closing your eyes, turn off the lights, then open your eyes. How long does it take before you can clearly see the items ahead of you? Do the same thing but this time while your eyes are closed, turn the lights back on. How long does it take this time?
This is simular to the way shutter speed is affected by light. In this example your eye lids are acting as the shutter. When there is more light the shutter is able to open and close more quickly as the light is able to expose the film or sensor faster (both are light sensitive) while creating a properly exposed images; however, when the room is dark, the shutter must stay open longer to use the limited light to capture the detail and properly expose the image.
Shutters have gone through many different versions since the creation of the camera starting out with replacing the cap as your control of shutterspeed or length of exposure to the current curtain shutter speed increasing the efficiency of the shutter.