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Is this correct on freezing motion and HSS?

Hi guys is this correct. I think (I hope) I understand flash, ambient and freezing.

1. If shooting outside in bright ambient light or inside a studio with bright continuous light we can crank the shutter speed to freeze motion because no flash is involved. So syncing doesn't matter.

2. Using a small aperture you can kill the ambient light if your strobe has a fast flash duration and still shoot within your cameras sync speed and freeze motion.

3. You can freeze motion even at slow shutter speed 1/15 second if there is zero ambient light and only flash. 

4. If mixing ambient and flash and using the shutter speed to underexpose the sun or ambient light you need HSS? 


  • Neil vNNeil vN Administrator
    The most correct answer to these:  Probably, but not Necessarily 

    Here is the related article:   will flash freeze the action at slow shutter speeds? 

    To go over your questions specifically: 

    1. Yes. You're just dealing with ambient light. 

    2. Probably.  If your ambient light is 5 stop or more under the ambient, then the ambient light won't register and you won't get ambient smear from the movement. 

    3. Probably, but not Necessarily:
    The problem comes in that we don't know what kind of action you're photographing. If you are in a studio and doing action portraits of an athlete, then you might very well not entirely freeze your subject's movements ... e.g., a martial artist doing a high-kick. With most studio lights you will get some blur on fast moving hands and feet. The flash duration of most studio lights are slow enough not to entirely freeze the action - you can see movement. 

    4.  Yes.

  • Ah thanks for that article Neil.

    I'm pretty close on #3 the strobes have these specs. Lower power, faster the flash.
    Godox/Cheetah 360 says: Flash Duration is 1/300 - 1/10,000s. So at 1/16 power I imagine it would be fast to stop say an athletic jumping etc??

    Another strobe says: Flash Duration 1/250 - 1/15,000 sec @ t.1

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