Flash SB-910 stuck with sync speed, shutter 1/200

camera64

I want to take picture outside at f/1.8 or f/2.8, but my sync speed is stuck to 1/200. I am way too overexposed.
The flash aperture is f/1.8 too. This makes pictures way too over exposed, but I still want the blurry background.
Thanks

bruto

The sync speed is at its maximum. You cannot go any higher than that. I am unfamiliar with the SB-910 and just how it operates, but I think what you need to do here is to reduce its output level considerably. I think it includes a sliding output level scale from which you can select lower power settings. If there is no way to do this to reduce exposure, then I suggest you find a neutral density filter, which is the easiest way to darken a lens without stopping it down.

In case you are wondering about sync speed, a short lesson in focal plane shutters, such as the one in your SLR follows. The shutter is actually two different mechanisms depending on speed.

The shutter has two curtains, basically, which open independently. At slow speeds up to "sync" speed the first curtain opens exposing the sensor, and after a period of time, the second then closes behind it. The sensor is, thus, entirely open for a period of time. At faster speeds, the mechanism is entirely different. The two curtains open up slightly, forming a slit, and this slit then passes over the sensor. The first part of the sensor is exposed before the last, and there is no time in which the whole sensor is open. Electronic flash is too short in duration, so speeds above sync speed will result in only partial exposure.

We're lucky. Up until the 1970's or 80's, most SLR's had a sync speed of only about 1/60, making daylight fill flash a huge challenge.

bruto

I will add that if you are getting overexposure from ambient light at that shutter speed (quite likely), and must use flash, then your only option will be a neutral density filter.

ohyeahar

Matt Granger did an excellent video on this topic.