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Booray: your explanation for the how the flash works is incorrect. The light travels at the speed of light, which is true. However the flash has a duration of how long it stays on. Technically this time is measuring using the term T1 time. T1 times, the duration that the light is on, can very depending on the flash power. Full power for a speed light can range to 1/250. At smaller powers the time gets extremely short. The flash duration is what freezes motion.

Flash duration can be longer or shorter but has a time span dependant on flash gun design and power setting. Speed of light is simply how fast the light travels from the gun to the subject and not anything to do with the flash duration. Flash duration is normally much shorter than a shutter duration.

I learnt something today. On a Canon G1X camera this is called Slow Shutter sync although I didn’t understand the situation to use this till now. On my Nikon D810 there is no such setting so you would have to just know this, although I haven’t had a close look in the manual yet. I am fairly sure it has rear shutter sync.

I like to get creative when dragging the shutter by ICM (international camera movement).

I"m not a physicist, I only play one on TV, but...I don't believe the flash freezes the motion because of how fast light travels (though that helps for another reason), but because of how quickly the flash turns on then off (strobes). The fact that that very short period of illumination gets to the subject and back to the lens very quickly does help though, as it makes the timing simpler (i.e. the camera doesn't have to figure out how long the light will take to get to the subject and back to the lens). 🤓

Very well explained, I have used this technique for capturing hummingbirds in flight to good effect.

This is very interesting. I'm not sure about the flash turning on "at the speed of light." Sure, the photons do so, but electronic components have a slew rate or rise rate that is usually not comparable to the speed of light. LEDs are faster than (just for example) incandescents but there's still a rise rate.

Nice video Booray. For those new to this - If you want to take a different looking waterfall or stream picture where it's not the typical milky effect caused by a slow shutter speed, DO do a slower shutter speed BUT add a pop of flash. That'll give a milky look AND some sharp "frozenness" (meaning of course time frozen not temperature frozen) - the result is sort of like a double exposure.

Thanks Very useful to understand this.

The flash does not turn on and off "at the speed of light" as "the speed of light" is not a measurement of duaration. Flash duration varies depending on various factors.

Awesome video! For those who have never shot weddings or events like me, this is the first time I've heard about it and I find it very fascinating. Thanks!

Speed of light is the same all over the picture. It is the duration of the flash that matters and it is faster than mechanical shutters.

Fascinating!

Very interesting, thanks

thank u!! well done!

Great job explaining this phenomenon. Dragging the shutter is a cool tool to use!

Hmmm. I've been using exactly this technique in the field for macro photography. I didn't know it had a name, and now I do. It is a very, very useful creative technique, as you have said. Sometimes it is also useful to do the opposite with flash and increase shutter speed to darken the background for any number of reasons.

Also to those who are new to this: It's interesting to ponder the relationship between the shutter speed and a flash - especially the intersection of the two. Sometimes your flash is the faster thing, sometimes the shutter speed is the faster thing (especially as with a leaf shutter, they don't have "curtains" and they are FAST!). When you think about this stuff for bit, creative ideas can happen.

I haven’t yet watched this video I just wanted to say that I have no idea what ‘dragging the shutter’ might be so I am looking forward to this!

Very nice video. Learnt something new today.

Amazing, thank you.. I realy want to up my strobe game, and this is perfect video for that :)

Love the video. Not all flash and flash powers are the same. If I'm using high power on my flash the flash duration is longer and I can pick up some blur. I do treat throws with dogs. Dogs are very fast. I have to make sure I have a short flash duration to really freeze them. Thanks again for another great video!!!

Thanks. I did not know what it was called. I do it but did not know what it is called.

One thing I'm unclear about: the naming! Not clear to me why this is called dragging the shutter. Is it because of the trial and error process you described at the end where you "drag" the shutter around until the background is exposed well enough but the subject is dark?

This is the problem learning photography off KZfaq. Id never even heard of this till now. That technique's pretty cool.

Am I wrong, or is this called curtain sync? Front or rear curtain depending on when the flash goes off. Never heard it called "dragging the shutter".

This is really cool. I had heard of the term and I'm not a Portrait shooter say in low light where you go to a band and there's music playing and you've got very low light situations. I can see how this would be really useful for that. Because mainly I shoot landscapes I don't really use this at all. In fact I've never used it but I've played around with it. I remember doing some product photography once and yeah I do remember this but I've never actually learnt how to do it properly. I can see many applications for this, especially in social settings where there is very poor light. Maybe someone on a dance floor where you want to capture them. Yeah I was thinking at Party's and I often get asked to do Friend's parties and things like that and it's difficult. So thank you so much for this. It's awesome to learn something new on a Saturday morning which is what it is here in Australia. Does it work with Off? The camera flash work as well I imagine it would but is there anything I need to do differently when I'm using the flash off camera

Another excellent tutorial … thanks! For my X100V, which flash mode should I use to drag the shutter?

I assume this doesn’t apply if the ambient light is hitting your subject, correct?

I guess it doesn’t really matter, but as others have already commented, the speed of light has little to do with it. It’s the duration of the flash

Hey Booray, Great subject, Wow 300,000 Kilometers per second i will be a Camera Nerd when i explain this in a Dinner conversation. Can this process be done when using a Tripod, and when doing long exposures at night and using the BULB mode would that be called Dragging the shutter as well. Very useful subject as i have a wedding to go to soon i will certainly take note especially when people are Dancing and the rest of the room is dark. Thanks for sharing. 😃

This is literally the VERY FIRST video of this "hack" that I have ever seen in KZfaq. Like no mention of this in any of the recommended videos at all. It would have been very useful to know two weeks ago when I did a work at a kid's birthday party (my very first photography work!). Thankfully I managed to get some great and good shots, but man if it weren't for the flash and a f/1.8 Sony E prime lens I might have been with not good enough pics. I will definitively test this out! By the way, speaking of events, do you think that the XF 50-140mm f/2.8 would be a good choice as an event lens. I feel more comfortable being at long distances so I like the pair of having a body with a zoom lens and another with a Prime for portraits.

Sorry but you’re way off with the physics. The speed of light has nothing to do with it. It’s the duration of the flash - completely different.

You're gaslighting wile being not incorrect about flashlighting, with lots of noise. I say this for people who might need to consider to override their sensitivity...

physics aspect of that explanation was wrong. but how it actually works doesn't really matter for viewers, so it's not a big problem.