Silhouette line across the frame, studio shoot.

[Sgdevilzz]

Recently i did a studio photoshoot with my friends. Everything is fine except when i change to a certain shutter speed, it gives me a thick black strip across the photo. Why is it so?

Settings:
1/250, f8, flash: Rear wb: Auto


For some reason, upon setting the shutter speed at 1/200 and below it works fine. What are the cause of it?

Using 2 Elinchrom BX500RI both left and right of his face and another BX500ri with snoot for background gradient.

 

[spree86]

Take note of the sync speed of the strobes to your body, your shutter speed is too fast, so the leftmost of your picture is severely underexposed

 

[photoart]

shutter is going too fast. It opens and the flash hasn't had the time to illuminate the whole scene before it closes. Slow that shutter down, check your manual for the right sync speed

The shutter is made up of two curtains. The first open opens, exposing the sensor/film, then the second one follows it to close the shutter. The time in between is the 'shutter speed'.

For very fast shutter speeds, the 2nd curtain might start closing before the first curtain is all the way open. This is a problem when using flash because the burst of light is very short, and of course, light travels at 'the speed of light'....so if the flash fires when the shutter isn't fully open, you end up with parts of the image that are severely underexposed (black line).

The camera will have a 'max sync speed', which is the fasted shutter speed at which the shutter will be fully open. It's probably in the neighborhood of 1/60 to 1/250.

So your solution is to always keep the shutter speed at or under your max sync speed when using flash.

 

[Sgdevilzz]

Thanks for the clarifications! So that is the problem. I will take note next time i do another shoot with flashes.

 

[sjackal]

You went above the flash sync speed of your camera.

Most pro spec-ed SLRs are 1/250, some consumer ones are like 1/200, some medium formats are 1/500, some older DSLR which uses electronic shutters are like 1/500 too.

Another possible problem, is your triggers faulty, or battery low.

 

[BrokenDown]

safest, shoot at 1/125 then adjust exposure with aperture