Maximum flash sync speed is a limitation which exists in mirrorless and DSLR cameras, but doesn’t exist in compact cameras and this is the reason stronger strobes (GN 30-33) are recommended with mirrorless and DSLR while with compacts you can do well with weaker, entry level strobes (GN 20-24).
Detailed explanation:
A mechanical shutter in a camera usually consists of two curtains – Rear curtain and front curtain.
When you shoot, the first curtain opens from the top down, revealing the sensor and starting the exposure, then the 2nd curtain closes from the top down, to end the exposure.
This happens very fast (often as fast as 1/8000s – i.e shutter speed).
If the chosen shutter speed is faster than 1/200s (more or less, depends on the model), then the 2nd curtain starts closing before the first curtain has even reached the bottom, so at any given point the entire sensor isn’t exposed.
This means that if you’re shooting a flash, which is much faster than any shutter speed, you won’t light up the entire frame, but only a stripe of light in the middle of the frame.
That looks like this:
In order to use a flash, you have to use a shutter speed that reveals the entire sensor momentarily – slower than 1/200s (i.e Maximum Flash Sync Speed).
This limits you very much in bright daylight or shallow dives when you want to get rid of ambient light. In those cases, you need to reduce your ISO and/or Aperture, instead of using your shutter speed (since you can’t…).
This also reduces the intensity of your strobe, which means you have to increase the power output. This is where stronger strobes come in handy.
Compact cameras have an electronic shutter, which isn’t limited by the above phenomenon, so it’s capable of shooting with a flash at very high speeds. This helps you get rid of ambient light even in shallow water / bright daylight conditions.
You can use any shutter speed you want, up to the camera’s own limit, which can be 1/2000s or even more.
This advantage allows you full control over your background, as well as enables you to use weaker strobes.
If you are using a mirrorless or DSLR, then we recommend getting the stronger strobes to help you overcome this limitation.
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3 comments
The last bit of this article that mentions compact cameras is incorrect. The reason compact cameras have significantly higher flash sync speeds is due to their leaf shutter system and has nothing to do with electronic shutter. There are actually very very few cameras that can actually fire a flash with their electronic shutter enabled. Also, you don’t mention high speed sync at all which seems pretty pertinent.
The last bit of this article that mentions compact cameras is incorrect. The reason compact cameras have significantly higher flash sync speeds is due to their leaf shutter system and has nothing to do with electronic shutter. There are actually very very few cameras that can actually fire a flash with their electronic shutter enabled. Also, you don’t mention high speed sync at all which seems pretty pertinent. Thought y’all should know
Hi Ben,
Thanks for your comment! You make a good point, electronic shutters do have some major limitations at present in allowing strobe synchronization, I think mostly as a result of pixel readout speeds; however, it seems that major breakthroughs in this regard are imminent! Global shutter may be the answer to all of these issues, if it can be done (and the camera rumor mill always seems to suggest it’s right on the horizon..). As you point out, leaf shutters like those found on many compacts typically do have higher flash sync speeds than focal-plane shutters. This article is meant as a starting place in this topic, we will update with a more in-depth exploration of this topic soon. Thanks again and happy shooting.