What shutter speed do you use with flash to control motion blur ?

mikeyw

mikeyw

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I was taking some images recently where the subjects were fairly static and i was getting perfectly acceptable results at 1/60 and f6.3 using TTL flash. All of a sudden one of the subjects started moving their hands which introduced some distracting motion blur.

I'd not planned of this happening but it ruined the picture somewhat.

To give yourself contingency for this is 1/125th enough or would 1/250th be a safer option ?
 
mikeyw said:
I was taking some images recently where the subjects were fairly static and i was getting perfectly acceptable results at 1/60 and f6.3 using TTL flash. All of a sudden one of the subjects started moving their hands which introduced some distracting motion blur.

I'd not planned of this happening but it ruined the picture somewhat.

To give yourself contingency for this is 1/125th enough or would 1/250th be a safer option ?
Click to expand...

Only a guess, but I`d say 1/250 with using the flash and if you still get blur you don`t want then up the shutter speed a bit more.
 
Just some hand movements so not freezing someone jumping, just annoying it happening when if i used 1/125th as a default it may avoid it in future.
 
The flash will synchronise at whatever speed your camera runs at, mine for instance is 1/180 so that's the max I can set else the flash wont fire (or that's my understanding). I think what you have here is a second image being caught by the settings you are using. In effect the flash is doing nothing, apart from maybe fill-in. You have I believe exposed the image based on values for ambient light. If you are in reasonable light, say outdoors on a summer's day then 1/60th at f6.3 might be enough to correctly expose for ambient light, depending on Iso setting. So to freeze motion you need the flash gun to illuminate the subject matter and not ambient light.
So I would use the fastest shutter your camera will synchronise at (could be anything from 1/60 to 1/250th - for most normal camera/lenses these days, older Med Format had special lenses with focal shutters I think they were called which synchro at all speeds), plus an aperture that wont expose for ambient light based on required Iso setting. The flash will then expose and freeze subject movement, what you have to careful of though is getting an underexposed background.

At least that's my understanding of the theory, cant say I have ever put it into practice. Have a word with Phil of this parish, he seems to have a good grasp of it.
 
mike weeks said:
If using flash then you have to consider 2 exposures, the flash and the ambient, generally the flash duration will be shorter than the ambient so there could be a flash frozen moment within the blur captured by the ambient

Mike
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This^
 
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