High Speed Primer - Introduction
We have done quite a bit of High Speed Photography here on DIYP, but never took it from a step by step approach starting with the basics and moving up to elaborate setups. This is going to change today.
Starting today, and for every Monday in the next few weeks, high speed photographer Brian Davies is going to go show us the ropes on high speed photography. Brian is just your ordinary guy who loves to play with high speed, so the series is not going to be exclusive for lots-of-gear-super-techy-rich photographers, it is also aimed at the entry level togs who want to get some hands on with high speed. Actually there is very little that you would need other than a camera, a strobe, and a tripod to start with. All the high speed electronics can be DIYed if you have some basic soldering skills, or bought if you have a bit of extra green in your pocket. (Actually, for the triggers we show in this series, no soldering is neeed, they are on breadboard based).
And now, I step off and give the floor to Brian.
My slightly more unusual pictures are created using a number of home-made gadgets... well, I shall call them "technical devices," which sounds a lot more impressive!
After a few requests along the lines of "how did you do that," I've decided to outline the basic techniques here. You Can always come back to this post for the "Intro/Map" to see what's coming...
- Introduction (this post)
- Low Cost Set-up
- Better Trigger And Cherry Drops
- The Woosh
First some examples, to either whet your appetite or steer you away:
First of all, I'm not purporting to be any kind of expert - I only took up photography after I retired and bought my first ever camera in the autumn of 2007. I have learned everything I know from other kind photogs who were willing to share knowledge and ideas, mostly via the Flickr picture sharing site. This is just about paying it forward... and of course to give a chance for people who know better than me to comment and offer suggestions, corrections and better ideas!
A couple more examples// "timing is everything"
The high speed pictures capture an event (such as a cherry splashing into a bowl of cream) with a very short exposure time. Usually, the "impact event" is too fast for the normal shutter speed of your camera. In the case of the popping balloons, eggs shot by arrows or air pistols, and so on, you would need a much shorter exposure time than a shutter can provide if you want to freeze the motion.
The most common trick is to use a flash unit. The xenon (eg "speedlight") flashes can often have their power output turned down (in manual mode) and they do this in a very helpful way. Instead of reducing the intensity of the flash, the duration is reduced. So at half power, say, the flash is "quenched" when half the normal amount of light has been emitted. At 1/128th power, the duration of the flash is somewhere around 1/30,000th of a second. Even quicker according to some sources. That's short enough to freeze the "explosion" in all the pictures above. It won't freeze a bullet in flight, but it will freeze the explosion that the bullet-strike produces. Pretty much :-)
So this is how it works: Set up the event (fix the target, aim the.. crossbow in my case) then turn the lights off. Open the camera shutter for a few seconds, and fire the flash - at low power - just as the impact occurs. That, of course, is quite hard. Even with a cherry drop or a water drip - relatively low-speed events - getting that timing just right is quite a job, and I'll explain how I do this in what follows. The important thing is that the only light reaching the camera is from the very short flash, so it's like having a super-fast shutter speed.
You could TRY and fire the flash at just the right time, but the odds are you will have to do a lot ( a proper LOT) of tries to get the shot! The solution is to make or buy an event-trigger that can fire the flash for you at just the right time. For example, a sound trigger picks up the bang of the crossbow/pistol firing, or an infra-red beam is broken by a falling cherry. If you then use a (simple) circuit to add a slight - and adjustable - delay between the triggering event and the flash, you can take the picture at JUST the right time. Job done!
You can connect the output from your event trigger/delay unit to your flash by cable, but it is much more convenient if you use a wireless flash trigger. This especially applies if you want to fire more than one flash unit - which is often a good idea since 1/128th power means a short but not very bright flash. Also, you may want a second or third flash to light up a background or something.
It can get a bit confusing if you are new to this, since the wireless flash triggers are often just referred to as "flash triggers" and the event triggers are too.
Ok, so the setup is:
- a sound or optical trigger that is activated by the "first event" (gunshot, dropped cherry)
- a delay circuit that counts a tiny fraction of a second then fires the...
- wireless flash trigger transmitter - connected to the delay unit. This immediately (pretty much) activates the...
- wireless flash trigger receiver(s) which are connected to and fire each flash unit.
Remember, while all this is going on, the room is dark and the camera shutter is open - on 'bulb' for example. After the flash, the shutter closes and smiles all around. Sometimes :-)
Lights (off), Camera (open shutter), Action!
Here is my first (home made) bit of kit, showing the sound trigger (grey box), delay unit (black box) and wireless transmitter: as used for the egg picture above.
The circuit designs here are all courtesy of HiViz (www.hiviz.com) Their website is a treasure trove, and have all the schematics needed to build a complete high speed photography system, as well as some affordable kits.
For some (slower) events, I have used a wireless shutter release (yes, a third type of trigger!) to operate the camera shutter, and let the camera operate the wireless flash transmitter. But the latency (built-in delay) in getting the shutter to fire that way was already way too much for the fast events using the crossbow or a balloon pop. Probably the fault of the wireless shutter release, to be honest, but the method described here lets me set the delay completely using the little black box...
You'll note in that picture that my kit is in neat boxes: after realizing that this was SO much fun I decided to make a more permanent job of the circuits. The boxes and sockets cost two or three times as much as the electronics inside. Not kidding! And I had a few of the sockets lying around from other projects. Sound trigger circuit : £4, about $7US I suppose - without the fancy box, and it works just the same.
On The next post we will explore some of the available High Speed Photography Triggers
About The Author
Brian Davies is a photographer and a Retired educationalist based in Hull, UK. You can follow his flickr stream here.