Shooting with a flash

timfrommass · Dec 17, 2009

I have a lot more work to do in terms of my composition and general exposure before I really dig into lighting, but I have a basic flash question. When I use either my in camera flash (on the D90) or my Dad's old SB-24 which I tried out for the first time yesterday I'm limited to 1/200sec exposure time. Is there a way to remove this limitation? If not what's the reason for it?

-tim

Goontz · Dec 17, 2009

1/200 shutter is the flash sync speed for the D90, so you won't be able to go any faster than that while using a flash. Let me poke around for a moment and hopefully I can find a video that another user has posted here before that should be very helpful.

Village Idiot · Dec 17, 2009

There's a high speed sync option you should be able to use though. That makes the flash pulse in the time that the shutter curtain is open to get a full exposure. You really lose power with an HSS mode though.

Goontz · Dec 17, 2009

This is the video that I was looking for. It does a good job of explaining sync speed.

KmH · Dec 17, 2009

The reason for it is the way the shutter works.

The shutter is actually 2 curtains. nikon calles them the front and rear curtain.

At 1/200 both curtains are open all the way. At faster shutter speeds the curtains form a moving slit. The slit is narrowest at 1/4000 second.

To do flash at shutter speeds higher than 1/200 the camera and flash have to be capable of FP sync mode.

FP sync mode fires the flash several times during an exposure and will significantly speed the depletion of battery power and lengthen re-cycle times.