I used to love doing that trick when I had my camera at parties. One second exposure with flash. Get your subject and flick your wrist to get cool light streaks
That would be front curtain sync, rear curtain is when the flash triggers just before the shutter starts closing.
Rear curtain is great for moving subjects, because you get trails behind the subject from what they were doing before the flash happened. If you're going to move the camera dramatically to smear static light sources then you want front curtain or you'll never line the subject up at the right time.
Shutters used to (high end cameras still do) have two moving elements (called curtains because the original ones were in fact fabric). When you open the shutter the first one opens, then once the time has elapsed the second one starts to close over the gap (you can't just use one because otherwise parts of the image will be exposed to light for longer than others).
In old fashioned cameras there were contacts built into the first and second curtain mechanisms to trigger the flash (now it's all electronic).
There's also a speed (flash sync speed) beyond which if you use a flash only part of the frame will be exposed, the is because for fast shutter speeds the second curtain will start closing before the first has finished opening (so the image is exposed in parts) because the mechanical components can only move so fast (a lot of modern cameras will do this electronically instead).
I remember reading about a special kind of flash that's quite expensive and is highly synchronized with your camera for daylight photography (very bright environments like the beach) where the flash is used to illuminate a swimsuit model.
Is the trick there that the flash lasts longer than the shutter is open?
This was as far as I remember for flashing the foreground at shutterspeeds of 1/5000th and so on.
Most modern flashes can do this (they pulse the tube very fast) at reduced power.
But yes you could get magnesium based flash tubes (single use, bad for your eyes due to lots of UV) that would burn for long enough the moving curtain wasn't an issue. There were probably xenon ones too (just need a large bulb and the power to run it, most camera mounted flashes are too small for this).
Another trick in daylight photography is to use a reflective surface to get fill lighting.
I’m a pro photographer and I came here to say this. If the exposure depends on flash, then it’s the flash speed, not the shutter speed, that determines if it’s frozen.
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u/QuinQuix 21d ago
This is the real answer.
Incidentally you can create similarly amazing party photographs putting your shutter at a slow speed and also flashing inside of that window.
You get dynamic light stripes but the real picture is frozen into it razor sharp thanks to the flash.