Sunday, August 28, 2011
Elements of Exposure - Bring it all Together - Part V
Now that we know how each exposure control works independently let’s look at how a photographer may go about combining them to achieve a look that expresses their intent. In most cases I recommend starting out at ISO 100, if in a low light situation than you may need to boost that up to what’s needed keeping in mind the introduction of noise at high ISOs for your particular camera. Every camera will be different; with some cameras you will be able to go much higher before noise becomes a problem. You should test your camera by shooting a darker scene that has a majority of a single tonality and take a series of images at increasing ISOs to determine what is acceptable for your set up. The dark mono-tone subject is the easiest way to see noise and help you identify when it becomes unacceptable. An average DLSR can generally go to 400 or 800 ISO and some to 1600 ISO without a significant reduction in quality caused by noise.
The next decision should be based on the desired affect you wish to capture as controlled by the shutter and aperture. If motion bur control is your primary concern whether it is to freeze your subject or blur your subject you should dial in the appropriate shutter speed to achieve that result than dial in the aperture that provides the correct exposure. You may have to change your ISO if you cannot achieve the affect you are after at your chosen shutter speed. If your primary concern is depth of field than you would want to dial in the aperture value that gives you the depth of field you are after and then the appropriate shutter speed that provides the correct exposure. Again, you may need to adjust your ISO to achieve the desired aperture setting.
By manually setting all three exposure adjustments you will be sure to get the desired effect in your images. However, it will take some time and practice to become efficient in this process, but having this control is worth the effort. How do you know where to start? I suggest you take a look at some of your best images you shot in full automatic mode. You can review the setting in the EXIF data that auto selected which should help establish a starting point. Next you might want to try one of the semi-auto modes where you select the ISO and one of the other settings and the camera will select the other setting to give you the correct exposure. After you mastered that you will be ready to go fully manual and your images should begin to improve as you get more comfortable.