Posted by Scott on October 20, 2016
For this image we were just playing around using some low power solar camping lights to light the image. They provided very little light but, that was all we had. I sat there with my guitar and Patty shot the image. The first decision was how much of the image needed to be in sharp focus. I wanted the tent and the guitar player (me) to be in sharp focus. But at the same time I needed as wide an aperture opening as possible to let the most light in. F4.0 which is wide open for this lens and it still gave me the sharpness I needed (some test shots showed that I had sharpness I wanted). Next I needed to use slowest shutter speed that I could, while still keep the guitar player (me) sharp. Because I was siting down and able to brace myself with the guitar, I could use a shutter speed of 1 second (you may need some test shots to determine the minimum shutter speed usable in your situation). Well all I had left was ISO and that was adjusted to obtain the proper exposure as indicated by camera. I like to use the aperture priority mode. For this shot I set my aperture to F4.0 the shutter speed to 1 second and simply adjusted the ISO until the camera showed it had the proper exposure.
This same principal works for many different types of photography. For example in wildlife photography; you pick an aperture based on what you want in focus (or what you want out of focus) you then choose a shutter speed that will freeze your subject and give you a sharp image (or blur your subject to show motion). And then all you have left is the ISO to get the proper exposure.