If you have recently upgraded your digital camera to a digital single lens reflex (DSLR) model or similar advanced camera, you probably are somewhat intimidated by all of its new modes and settings. Understanding Shutter Priority (Tv), ISO, Aperture Priority (Av), and Manual shooting modes is not always easy. Certainly the best way to learn about these settings is to shoot pictures – lots of pictures – while taking notes so that you can intelligently compare the results. Another way is to simulate the these changes.
I learned about a very cool website that does exactly that this past week. I was led to this site from the Digital Photography School in an article by Peter West Carey http://digital-photography-school.com/technical-flash-applets-from-stanford-university-make-photography-learning-fun-2. This link takes you to a webpage that has some very technical articles about the underlying principles.
But, there you can also link to a real cool applet on this webpage http://graphics.stanford.edu/courses/cs178-11/applets/exposure.html. This is where the fun begins. Instructions on the page tell you how to use the applet. Here is how the applet looks on your screen.
To use the applet, simply move the sliders and watch how the focus and brightness of the three figures vary. You can simulate the various shooting modes of Manual, Av and Tv, as well as ISO.
To get you started, set the ISO to 400, Aperture to f/16, Exposure Time (Shutter Speed) to 1/64 sec using the Manual setting at the bottom. Notice that while the middle figure is the sharpest, the ones in the back and front are also reasonably sharp. This is because the depth of field – that region in front of and in back of the subject of focus is relatively large at this small lens opening.
Change the the ISO to 100, the Shutter Speed to 1/250 sec., and the aperture to f/2. Now only the center figure is in focus. The depth of field has gone way down, because we have made the lens opening quite large. You can also, simulate the the Av and Tv modes.
Playing with this applet can be quite engaging and fun.
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