Flash Slow Sync And Rear Sync
Slow Sync. Normally, when you use an internal or external flash that is, the flash is synchronized on the first curtain. But when you need to make a picture of a dimly lit scene can however change this timing, moving second curtain. In this way, the lightning flash will wait for the shutter closes.
the second-curtain sync, also called Slow Sync, allows you to capture the image are not illuminated by the flash but also to read the background exposure imagine to photograph a sunset, with the sun almost gone or an illuminated city akusaraprosound. Imagine also that you want to capture a subject in the foreground if sparassimo with esporremmo flash properly the person in the foreground, but we would get a black background (no city or sunset). If we have a super flash and we used it at full power, we could perhaps capture background, but hopelessly sovraesporremmo the person in the foreground. Slow Sync allows you to solve exactly this problem in this mode, the flash will emit a flash and, at the same time, the shutter will remain open for a much longer time in order to capture not only the foreground illuminated by the flash but also the background (the most time allows us to improve the exposure of the background, of course, in environmental enlightenment limits). To give an idea, look at this photograph
If we had used the first curtain synchro flash, the background would look much more black, underexposed. And goodbye sunset. Synchronizing second-curtain, the flash lit subjects that are properly exposed (the flash light is still set so as not to overexpose the subject) while the background was able to send a greater amount of light to the sensor since the same It remained open longer.reducing exposure or, if possible, directing the flash light toward a different point from the subject.
Obviously eye movements the slow sync is subject to rough because of the longer exposure. This problem, however, can be turned to our advantage picture taken with the flash usually means freeze your subject. With Slow Sync can also capture the motion with the flash, even if in a particular way the photo below a practical example which is captured a hand movement (due to long opening) but at the same time the same hand (and paper) are firm and well defined because of lightning froze the moment.