Paul C. Buff, Inc. Technical Forum

Yesterday I was shooting BMX with one of my friends. Usually my AB800 at full power is fine for freezing bikes in motion, but this time I got a lot of motion blur around the back wheel. This was shot at full power on the 800.




I know the t.1 is 1/1100, but the specs say that flash duration is worse as you power down. What can I do?

so did you shoot it at full power or not?

ambient light might cause motion blur, since the sun is quite strong.

Flash duration may be 1/1100 but your shutterspeed is not that fast..

The flash may cause the subject to freeze but the ambientlight will still be a major part of the exposure and that also causes motionblur.

Here is why:
1/250 = 4ms
Shutter opens, Flash takes 1ms, since there are ~3ms left of the exposure rider has time to move and cause motionblur.

Only way to reduce the amount of motionblur is to use a higher shutterspeed but that will also cause a black ugly bar in your picture.

Here is a great guide how to push your shutterspeed.

http://themgoods.com/forums/phpbb3/view ... 0e02adc51c

Be creative.. You may need to photograph upside down ;)

Also shooting later in the evening will help.

RMS

Yes, this was shot at full power. I'll remember the ambient light level next time.

Judging from the exposure on the trees not lit by flash I would say the blur is from the ambient light. A Nikon D40 type CCD camera is the real answer for this type of shot since you can use shutter speed of 1/1000 to 1/2000 or so and still capture all the flashpower and block out the ambient.