High Speed Photography using a DSLR and a cheap external flash is possible if you understand the physics behind it.
Your camera cannot take a photo of 1/20,000th of a second. You may be able to get 1/8,000th of a second, but you would need a lot of light to make that possible or a flash capable of “High Speed Sync,” but HSS reduces the light output of the flashes.
To do it “on the cheap” with a $80 flash is actually quite doable. If your in the market for a flash I recommend the Younguo 560 Series flashes. V3 and V4 especially. They are cheap flashes which will become more important when you want to use multiple flashes at once.
Physics Of The Thing
Flashes, or “Strobes” work on the principle that they only give out a specific amount of light at one time no matter what setting they are on. The “Power” of the flash is just how long this light is on. These flash durations are very quick.
For Example the Younguo 560 at full power is lit for 1/300 of a second. At its lowest power setting that flash is on for only 1/23000s of a second.
So you can imagine that in 1/23,000ths of a second things are not going to be moving much.
Your exposure will also be effected by the ambient light. To cut out all light but your flash, lower the ISO, or raise the F Stop to a larger number. But to completely cut out any light on your subject other then the flash, turn all the lights off. Sometimes just leaving one lamp on is good enough, and your less likely to trip over you camera and smash it on the ground.
Timing Is Everything
Now we come to the subject of timing. Imagine that you are taking a photo with a flash-duration of 1/23,000th of a second. That means you could potentially take 23,000 different photos in one second.
If you are trying to catch a bullet for example, in that second it may only be in front of your camera for 1/10,000s of a second, so if you want to get that bullet in flight, you have to get your 1/23,000th flash hit that 1/10,000 window.
Unless you are going to try to take this photo 10,000 times and wait for a lucky strike, you are gonna need a trigger of some sort. Lasers triggers for things that are quiet, and sound triggers for anything that makes noise are the most popular.
Trigger The Flashes Not The Camera
Another problem with your camera catching any high speed shot is camera lag. If your taking a bird in flight, your camera can keep up with it for the most case, but if your taking a photo of a firecracker going off, by the time the trigger tells the camera to fire and the mirror in your DSLR goes up and the shutter goes off there isn’t much left to photograph.
So How Do I Wire All This Up?
You can use radio triggers to set off the flash or flashes, but you can get a problem with all the flashes syncing. You will get ghosting if your flashes don’t go off at the same precise 1/20,000th of a second.
To do this I use old school PC sync cables all hooked together to make sure they all sync up. I use headphone extension cables to get to the flashes. I use a headphone hub to gang all this together. I purchase these on eBay real cheap. If you do that I recommend buying extra, as some of them will probably be defective. You will also have to get your trigger into the hub to set everything off. Some of these cables use a smaller headphone inputs. You may have to get a 2.5mm to 3.5mm headphone adapter.
Some Kind Of Sound Trigger
So How Do I Do This Simply, and With Less Math?
OK, lets get simple, say you are taking a photo of a balloon popping, this balloon happens to be covered in paint. You are going to pop the balloon from above with a stick with a needle on the end.
Everything is set up. The balloon is hanging in front of your camera on a piece of fishing line with a hook going threw the balloon nipple, your flashes are set up, your camera is locked down on a tripod. You have a pin on a stick.
If you are going to be messy, you may want to use a tent.
To make your life easier, get a good photo of the thing before you pop it, this will make sure your gonna get a good exposure. You can also test your sound trigger at the same time.
Shooting a Split Second Single Shot
1. Get the focus set. Focusing a little closer to the camera is a good idea if you want the bits flying closer to be in focus.
2. Set your exposure for the depth of field you want (F Stop)
3. Get the balloon centered and give some room to catch all the debris in the frame.
4. Set your camera to BULB.
5. Set all your flashes to 1/128th. You may get away with 1/64th and you may want the extra light.
6. Set the ISO to something you can live with. 400 or under is good.
7. Turn off the lights.
8. Lock the remote shutter release on to start the exposure.
9. Clap your hands to set off the flash.
10. Unlock the remote shutter release to stop the exposure.
11. Turn on the lights.
12. Check your photo to see if your in business. If the photo is too bright you can lower the ISO or use a higher f/stop and if its too dark you can raise the ISO or lower the f/stop or a bit of both. You can also move the flashes around to affect the exposure. Experiment with different settings and flash placements and going back to #7 until you are happy. Somethings can be fixed in post.
13. Once you are happy with the photos your getting without the balloon popping its time to pop some balloons. go to #7 but instead of clapping your hands, use the pin to pop the balloon, preferably from the top, so your stick isn’t in the frame. You may have an issue with the sound trigger timing. Most can be set with a delay in milliseconds. This is more useful if the noise and the “photogenic moment” are farther apart in time.
14. Do a happy dance. Put the photo on social media and when someone asks you how you did it, link here.
For an example on how you can edit this type of shot check here.
Trigger The Camera Not The Flashes
If a glass is breaking or you are popping a balloon, you only get one chance to take one shot. Setting the camera up in BULB in a dark room and triggering the flashes once when that action happens is ideal.
Sometimes you are photographing something where timing isn’t that critical and you want to get a bunch of quick shots and pick the one you like the best. You may want to take rapid fire shots as soon as something starts moving, like paint dancing on a speaker or spinning off a drill bit. In this case you will want to trigger you camera and have the camera set off the flashes.If you camera lacks a PC-Sync out to trigger the flashes you can buy an adapter cheap on eBay.
Shooting High Speed Bursts
1. Get the focus set.
2. Set your exposure for the depth of field you want (F Stop).
3. Get the subject centered.
4. Set your camera to high speed burst.
5. Set all your flashes to 1/128th. You may get away with 1/64th and you may want the extra light. Set your camera to your highest sync speed, usually 1/200s or 1/250s.
6. Set the ISO to something you can live with. 400 or under is good.
7. Turn off the lights. This is less necessary here as your exposure is much quicker then when you are in bulb mode. You can probably just get away with turning the lights down.
8. Use the cameras remote trigger to take a photo.
9. Turn on the lights.
10. Check your photo to see if your exposure is good. If the photo is too bright you can lower the ISO or use a higher f/stop and if its too dark you can raise the ISO or lower the f/stop or a bit of both. You can also move the flashes around to affect the exposure. Experiment with different settings and flash placements. Somethings can be fixed in post.
11. Once you are happy with the photos your getting its time to get some action shots.
12. Turn off the lights.
13. Hit the music, the drill or start whatever motion you want to capture while you use the camera remote to take a burst of photos.
14. Turn on the lights.
15. Ponder how your going to clean up the giant mess you have made. Next time use a paint tent to avoid such a mess.
16. Put the photo on social media and when someone asks you how you did it, link here.