2nd curtain sync

crazyjackphoto · Apr 22, 2008

hello, question abotu 2nd curtain. Actually i think image are better than words. Well, maybe help explain a little. How would shutter speed & apurture affect 2nd curtain. And since I'm already using flash how does aperture play in this. Photo are greatly appreciated, sorry if i'm posting in the wrong section. Thanks!!

Socrates · Apr 22, 2008

crazyjackphoto said:
hello, question abotu 2nd curtain. Actually i think image are better than words. Well, maybe help explain a little. How would shutter speed & apurture affect 2nd curtain. And since I'm already using flash how does aperture play in this. Photo are greatly appreciated, sorry if i'm posting in the wrong section. Thanks!!

Normal flash sync occurs slightly after the first curtain is fully open. Rear sync occurs slightly prior to the second curtain beginning its movement (to close the opening). Technically, the sync does not impact aperture or shutter speed. However...

The typical use for rear sync is with a very slow shutter speed, perhaps a quarter of a second or even slower, so that ambient light exposes the film or sensor in addition to the flash. The ambient light causes a blur in a moving object, perhaps a car, while the flash causes a crisp image. If you use normal front curtain sync, the blur will be in front of the car, making it appear to be traveling backwards. Rear curtain sync puts the blur behind the car.

christopher walrath · Apr 22, 2008

crazyjackphoto said:
hello, question abotu 2nd curtain. Actually i think image are better than words. Well, maybe help explain a little. How would shutter speed & apurture affect 2nd curtain. And since I'm already using flash how does aperture play in this. Photo are greatly appreciated, sorry if i'm posting in the wrong section. Thanks!!

Not knowing which camera you have I will use my Minolta sr-T101 (as well as most film cameras with a shutter curtain) for an example. When the shutter button is depressed it trips the mechanism that releases the first shutter curtain to travel across the face of the film surface that will be exposed. At a predetermined amount of time the second shutter curtain will follow the first across the surface of the film. The entire surface of the film will be exposed simultaneously for 1/60 th of a second and slower speeds. The shutter cannot move faster than this. For faster times the second shutter curtain will begin to follow the first before it gets completely across the film. 1/125th, the second curtain will begin when the first is only halfway across. 1/250, one fourth of the way across. 1/50, one eighth. 1/1000, one sixteenth. So for flash usage, if you use a flash that is rated slower than the shutter speed, the flash will only be visible on a portion of the film and not on the other.

Aperture does not affect the shutter curtains at all, only the shutter speed. Aperture is light intensity, ISO is film sensitivity to light, shutter speed is, well, shutter speed. Aperture will affect flash usage. A larger aperture will capture light reflecting from surfaces that are closer and smaller apertures are used when the surfaces are further away.