The Relationship of Shutter Speeds and Apertures to Flash

Struggling to understand flash synchronization? Need a deeper understanding of how flash works with other settings on your camera? Watch this illuminating tutorial.

In this information-packed photography class, Karl breaks down the relationships between flash power, aperture settings and shutter speeds.

You’ll learn about:

  • Understanding flash sync speeds
  • The relationship between ambient light and flash
  • The relationship between aperture and flash
  • First- and second-curtain flash synchronization

You’ll learn how each of these can work together to influence the final image.

In this class:

  • How shutter speed works in photography
  • Sync speed vs flash duration
  • Leaf shutter vs focal plane shutter
  • Shutter speed and aperture
  • The impact of ambient light on an image
  • Controlling flash exposure
  • Combining studio and ambient light

If you enjoy this class, check out Understanding Flash Power and Fast-Flash Jelly Headshots.

Questions? Please post them in the comments section below.


  1. I’ve always had the issue of experiencing a cap on my shutter speeds when I was connected to my FJ400 strobe. Despite being in HSS mode on the trigger, strobe, and in camera, I could adjust my shutter to 1/250 or higher, but the camera would automatically readjust to 1/200 once I engage the shutter to take the photo. Not sure why this is. I currently use a Canon R6II but also experienced this issue when I used my previous Canon Rebel T8i model

    1. Hi, if you are in full manual mode on your camera then this shouldn’t happen as the camera should give you total control, it may be that there is a sensor on the hot shoe where the trigger or flash goes that over rides this but that would defeat the purpose of having a full manual mode. Check in the camere menu settings if there is an over ride for flash sync speed.

      1. Wow I tried the same thing with a speed lite instead and didn’t have that issue. The FJ-X2m flash trigger must not be registering with my camera. Will research if there is any other accounts of this issue online.

  2. Another observation is that HSS works differently in different camera systems. Canon is very primitive because is elongates the flash duration as you explain. However Nikon HSS is the most sophisticated and adopted by Leica. The HSS flash output is in pulses so requires a lot of power. The faster the shutter speed, the more power you need for more pulses.

  3. Probably the best explanation on the world wide web.
    Just one issue. Focal plane shutter only travels forwards. This means both curtains travel in the same direction. So waving the black card apart from each other is not correct because they are moving is opposite directions! Also most focal place shutters run horizontally not vertically. Only later cameras had vertically running focal plane shutters.

  4. Hi Karl,

    I have a question regarding the flash function settings. Are options for first and second curtain flash synchronization available in Nikon Camera as well or not?

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