Saturday, March 28, 2015

Preface to "Understanding Explosure"

High-speed photography opens up many new opportunities to the keen photographer. Surprisingly it’s not as difficult as many may imagine. Usually the first response I get from someone who sees a nicely captured high-speed image is “You must have a really fancy camera.” My response is always “Give me your camera and I’ll take the same photos with it.” It’s not about spending lots of money on fancy cameras, and special equipment, it’s more about knowledge and the intelligent application of it when taking photos. Anyone who has a camera that can work in manual mode can take decent high-speed images. Even a cheap compact camera without manual settings can sometimes be forced into a mode that will allow for the photographer to get the job done – try this if you’re not sure, turn off auto-iso, flip to shutter-priority and 2 seconds and you’re ready to go! It’s as easy as that to get started so don’t go buying more gear just yet.  
The first few chapters will deal with how simple it is to switch a flash, and some cheap and easy ways to do this to get you started. We’ll discuss bursting water balloons, smashing light bulbs and other ‘safe’ ways to get impressive photos with your camera and a few cheap accessories. Then we will discuss the sound activated flash trigger, something that will require about $20 outlay and perhaps a little more knowledge and confidence to put together, unless the units can be easily purchased ready made where you live, which is quite likely but will cost slightly more. 
The second half of the book though, will involve something a little more dangerous that should not be attempted by anyone who does not know how to work with high voltages. When you start pulling flashes apart and working with capacitors you are working with voltages around the 200-600 volt mark, and extremely high currents due to the nature of capacitors and how quickly they can supply energy. 
There are many YouTube videos on modifying a disposable camera to work as a Taser that will make your hand numb for several hours. Those cameras have a tiny capacitor smaller than the smallest segment of your little finger. The capacitors in a normal size external flash however, are a lot bigger and could possibly blow your fingertips off and fry your heart all in a fraction of a second, if you touch the wrong wires. All I will say is that you shouldn’t try any of this yourself if you are not a qualified electrician, and if you are then you need to take the proper safety precautions when manufacturing the equipment, unlike my back-yard endeavors. 
To put things in perspective I used to grab the 30 000 volt electric fence around our workshop back in South Africa, just for ‘kicks’, it was designed to keep people out. One hand on the metal fence and the other grabbing the wire and it would throw me off in one swift break-dancing movement. The main difference here being the fact that those fences are a very low current in comparison to what a capacitor can deliver. I would never even think of touching the wires from a ‘mere’ 100volt capacitor even though it is ‘only’ 1/300th of the voltage of that fence, because it’s not the voltage but rather the current that can kill you, and a capacitor holds, and delivers, a lot of current. So be careful, this is highly dangerous stuff!  
We will also discuss the ‘spark generating flash’ and the ‘wire exploding SCR’ rig. An electronic ignition coil in series with a flash capacitor can generate 30-50 000 volt sparks for some interesting effects in photos. And a silicon-controlled rectifier is a great way to switch high voltages and currents for explosive photography, and is really good for igniting gunpowder for some impressively ‘different’ photos. Our discussion on igniting a fireball of gas examines the difficulty of actually doing this since the correct air-ratio is needed to create an explosion, which actually makes me frustrated when I read about accidental explosions when it’s so hard to create an explosion on purpose!
This is where things need to actually slow down a bit, because many of the techniques involve really high speed switching which can leave you with photos of an exploding wire while you miss the actual fireball a few moments later. This is where taking videos and using fast frame-rates are unavoidable and things get a little more hit-and-miss. 
Keep in mind the fact that I have been accused of not being artistic enough with my high-speed photography so take this book as a guide to the mechanical aspects of the subject for you to use as a foundation for artistic photography, not a book of amazingly artistic images. After all, most of the time I didn’t even know if something was going to work so there wasn’t much point in wasting time setting up an amazing background. 
What you will need: 1) Any camera that has the ability to be set manually 2) a PC cord to connect the flash to a switch 3) If the flash does not have a built in PC socket you will need a hot-shoe adapter with a PC socket on the side. Some optic slaves have a PC plug built in and can be useful for other triggering methods to be explained a little later so it is worth getting one now. 
Hopefully you are now chomping at the bit and want to get started, so without any further ado we will discuss the simple switch method of high-speed flash photography! 

Ok, slow down a bit, first we need to discuss how to get the correct exposure, if that’s ok? If you already know that then skip the next chapter and start getting the neighbors worried! 

No comments:

Post a Comment