Indy Photo Coach 10:02pm, 2 March 2010
There is a relationship between shutter speed, aperture and sensor speed (ISO). You can use this relationship to your advantage when hand-holding your DSLR in low-light situations not allowing the use of flash, such as in some churches and museums. For example, you meter a scene, such a one described above, and the shutter speed comes out too slow to hand-hold. Generally, we can’t hand-hold slower than 1/30 second and get a clear image. You can gain a faster shutter speed by either:
* Selecting a smaller number aperture.
* Selecting a higher number ISO.
Many times we do not want to adjust the aperture because of the depth-of-field we want in the image. By selecting a two-stop higher ISO, such as going from ISO 100 to ISO 400, you gain two stops of shutter speed. Many times, this results in a speed fast enough to hand-hold and get an image not blurry from camera shake. If your DSLR has Image Stabilization, be sure to have that turned on also.
1. Visit a large indoor facility, such as a mall, church or museum. With your DSLR set to aperture priority and hand-holding your camera, meter on a subject. Note: the current aperture and shutter speed
2. Now increase the ISO by two stops (e.g. if at ISO 200, a two-stop increase would be ISO 800 [1 stop = double or half of the current value).
3. Meter again and note how the shutter speed has now changed by two stops as well. For example, if your shutter speed read 1/15 sec. before, it should now read 1/60 sec. – fast enough to hand-hold.
Written by Ron Kness
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