Slow Speed Synch Flash
Understanding Slow Speed Sync Flash and Shutter Curtains
In order to discuss slow synch flash, we need to elaborate on the subject a bit. The purpose of using a flash is when you're in low-light or other challenging lighting situations and want a proper exposure. In many cases when the light isn't adequate, you lower your shutter speed. However, at a certain point (below 1/30s if you can really get your body still, otherwise 1/60s) you'll get camera shake, and motion blur can ruin the photo. In such a case, you're forced to use the standard flash. In addition, there is a third option, and that is the slow sync flash.