Hacking Digital Cameras

John Wiley & Sons

Chapter One

in this chapter

* Making a Wired Remote Trigger

* Making a Delay Trigger

* Making an Interval Trigger

* Connecting the Triggers to a Point-and-Shoot Camera

* Extending the Remote Switch

One of the first camera hacks I ever performed was the extension of the remote trigger release on my Canon EOS SLR: I extended it to shoot pictures of myself on roller skates from a distance. The hack was so easy I soon learned to make trigger switches as well. Trigger switches and extensions can serve purposes other than self-portraiture. You might want to set up your camera gear in a remote location to photograph birds and other animals in action. Sometimes I would set my camera in my hamsters' cages to capture their daily activities. Another popular remote trigger application is shooting sporting events. Photographers have been known to rig their gear inside hockey rinks and even in goalie boxes, generally using wireless triggers. But nothing is stopping you from running wired camera equipment to the basketball hoop in your yard. Mounting your camera there can render some awesome pictures of your kids playing basketball.

This chapter helps you make trigger switches and extend their ranges. If you have trigger switches from older generation cameras, you may be able to adapt them for use on your new state-of-the-art cameras. This chapter shows you howto make those adapters. Most single-lens reflex (SLR) cameras have a built-in shutter trigger port, and you connect to this port directly. But most point-and-shoot (P&S) cameras lack this nifty feature. On these cameras, you hack the camera itself and wire a trigger port directly to the shutter switch. This trigger port will use the same interface as the one available on SLRs, so if you have both types of camera systems, you can use the same remote trigger switch and extender for all your gear.

Making a Wired Remote Trigger

Most SLRs, even entry-level ones, have a remote shutter release socket so you can shoot pictures without actually touching the camera body. The remote trigger is used often in long-exposure photography, where even a small amount of vibration can introduce blurriness into the image. As steady as your hands are, they are not machines, and, therefore, they are prone to tiny movements that you may not be aware of until you view your picture. With a wired remote trigger release, the camera body can be mounted on a tripod, and you operate the camera through the wired remote trigger.

In astrophotography, exposure can take several minutes. If you had to operate the camera shutter with your hands on your camera's shutter button, they would probably be shaking like mad after five minutes. Holding the shutter button down for a long time is extremely tiring. Fortunately, many remote shutter triggers can be locked in the down position. An older mechanical trigger without the locking feature can be taped instead.

Remote shutter triggers are usually optional accessories for SLRs. They can cost anywhere from five dollars for a mechanical version to several hundred dollars for a super fancy electronic version. In the following sections, you build your own simple remote trigger so you understand how a remote trigger works. This knowledge will help you to build fancier timing triggers and multiple-camera triggers in the later sections of this chapter.

How Does a Remote Trigger Work?

On most of today's cameras, a remote trigger works simply by closing an electrical circuit to trigger the shutter. This simple concept is shown in Figure 1-2. The wired remote is simply a switch extended from the camera body.

Note

This chapter makes extensive use of circuit diagrams. See Appendix B for a list of circuit symbols.

A camera that has auto-focus (AF) capability generally has a two-position shutter trigger. The first position-reached when you press the trigger halfway down-closes the circuit for the auto-focus function. The second position-reached when you press the trigger all the way down-closes the shutter circuit. A wired remote trigger moves these two functions off the camera, as shown in Figure 1-3. Most Canon SLRs use this simple circuit for remote triggering.

Nikon SLRs use a slightly more complex circuit. The shutter circuit is simply an open/close circuit, like that shown previously in Figure 1-2. But the AF circuit is an open/close switch along with three 1N4148 diodes wired in series. The Nikon wired remote trigger circuit is shown in Figure 1-4.

Parts You Need

Your local electronic store carries all of these parts. I prefer Radio Shack because the stores are everywhere. You can also order the parts online from RadioShack.com. I have listed the Radio Shack part numbers for your convenience.

* Mini SPST Momentary Switch (275-1547)

* SPDT Submini Slide Switch (275-409)

* 3/32" Submini Phone Jack (274-245)

* 20-gauge wire (278-1388)

* Mini Project Enclosure (270-288)

Note

A 2.5mm jack is the same size as a 3/32" jack.

There are many different types of switches (see the "Switch Terminology" sidebar). Each one serves a slightly different purpose. Sometimes, two types of switches can be used for the same purpose. For this project, I chose to use two momentary switches and a slide switch. The normally open momentary switch (see Figure 1-6) is similar to the on-camera shutter button. A normally open momentary switch requires that you hold down the switch to close the circuit. As soon as you let go of the switch, it opens the circuit again.

Although this switch is appropriate as a shutter release for high-shutter-speed pictures, it would be tiring to hold down a momentary switch for a long time (minutes or hours), such as during a bulb exposure. To relieve you from having to hold the button down, most remote triggers have a locking feature that holds the button down for you. I have chosen a slide switch (see Figure 1-7) to simulate that feature in this project. When you begin the exposure, slide the switch to on. When you are done with the exposure, slide it to off.

Note

Bulb exposure is the term that describes what happens when you control the shutter's opening and closing without using the camera's shutter speed timer. It's generally used for a long exposure in astrophotography and nigh photography.

In this project, I chose a mini-project enclosure (see Figure 1-8) and a bunch of sub-mini parts to fit into it. These small parts help create a small remote trigger. A smaller remote trigger is easy to carry around and doesn't take up too much space in your camera bag. I also chose a plastic case because they are generally easier to work with than metal cases. It's easier to drill and shape plastic than metal.

Most photographers like to have a small, wired remote. I've noticed that there seems to be a general consensus that smaller is better, and there's nothing wrong with that. In fact, I picked a very small project case and a lot of sub-mini parts for this project. But you might consider a bigger box to fit bigger switches for action events. If you have rigged a camera in a hockey arena by the goal box, you probably don't want to miss a shot because you are fiddling for a button on your tiny remote. You might want to rig up a table-size remote where the button is the size of your hand, so that you can pound on the buttons during the excitement of the game.

For interfacing, I chose a 3/32" (2.5mm) stereo phone jack (refer to the "Canon E3 Connector" sidebar), shown in Figure 1-9. This is the same interface that is used on entry-level Canon EOS SLRs, so you can easily attach this wired remote trigger to them. This interface is common on cellular phone earpieces and other electronic components as well. Both female and male versions are common and easy to source. This is the preferred interface method compared to the proprietary interface found on higher-end Canon EOS SLRs, Nikon SLRs, and others. Later in this chapter I show you how to adapt this simple interface to the proprietary interfaces so that you can use the same remote trigger with the more advanced cameras.

You need some electrical wires to make the connections between the switches and the interface jack. You might already have some leftover wires at home. You can even strip them from your old stereo headphones (3.5mm) or your cell phone earpiece (2.5mm). You won't need very much of it, just about a foot or so of wire. I have listed 20-gauge wire in the part list. But any wire between 18 and 22 gauge will work just fine.

Tools You Need

Here are the tools you will need to complete this project:

* Drill

* Drill bit

* Small c-clamps

* #1 Phillips precision screwdriver

* Digital multimeter

* Wire stripper

* Solder iron

* 0.032" diameter 60/40 Standard Rosin-Core Solder (64-009E)

Cross-Reference

See Appendix A for information on buying and using soldering irons.

For this project, you need a drill to makes holes in the project enclosures for the switches. A low-power electrical version will work fine. The size of the drill bit depends on the switch size. It's easy to measure with a drill gauge, as shown in Figure 1-11 (see Chapter 18 for information about how to make your own drill gauge). Buy a set of drill bits so that you have many sizes on hand. Buying a set is generally cheaper than buying bits individually. Make sure you have a small c-clamp on hand to secure the enclosure on the workbench-you don't want to hold the enclosure with your hand. The drill bit could bite into the enclosure and the drill will have much more torque than your hand can control, which could lead to serious injury. A precision screwdriver is needed for fastening the enclosure together.

When you are ready to put all the electrical connections together, you need a wire stripper to strip the insulation from the end of the wires. A wire stripper costs a few bucks at the local home improvement store. The soldering iron and solder help you create good electrical contacts between the switch contacts and the wires (see Appendix A for a quick guide to the basics of soldering). You can find soldering irons and solder at Radio Shack.

Drilling the Case

The first step in making your own remote trigger is to drill the project enclosure. Before you do so, use the drill gauge to measure the hole required by the switch. Poke the switch through the holes in the gauge until you find the right size. Then mount the right sized drill bit onto the drill.

Before actually starting to drill, use the c-clamp to secure the project box onto the workbench (see Figure 1-12). My workbench has several holes over the surface for drill bits to drill through. If your workbench doesn't have the same facility and you don't want accidentally to drill into it, I suggest you place a block of wood between the project box and the workbench. With a wood block in between, when you drill through the project box, you'll drill into the wood block instead of your workbench.

After drilling all of the holes for your enclosure, test fit each jack and switch in the enclosure. This step is your chance to make sure the project box is drilled to your satisfaction, so you can make any additional modification as needed.

Soldering the Wires

When you are done drilling the enclosure, you can start soldering the parts together. Wire up the switches based on the conceptual circuit diagrams presented in the "How Does a Remote Trigger Work?" section. When you are ready to solder the interface jack, refer to the "Canon E3 Connector" sidebar for an overview and solder the connection to match the pin-out. Follow the instructions in Appendix A if your soldering skills are rusty.

After you have soldered all of the wires and contacts, you should test out your trigger before actually fitting everything together. No matter how confident you are about your result, you may find that the trigger is defective. I don't know how many times I put something together, whether it's an electrical project or an internal computer component upgrade, thinking it's perfect, but after tightening the last screw, it fails to work. So, before all the switches and wires and the jack are in the project box, plug it into your camera. Verify that all the switches are working as expected. If everything works properly, you can move to the next step. Otherwise, pull out your digital multimeter (see Figure 1-13) and test all of the connections.

Note

A digital multimeter is a multi-purpose electronic measurement tool. The digital multimeter can measure voltage, resistance, and current. Using the resistance mode, you can check for bad connections in your circuit.

Fitting the Pieces Together

After you've successfully tested the circuits, you can carefully fit everything into your project box. You may have to bend the circuit wires to fit the box. Try to bend them at sleeved unsoldered locations to prevent breaking the soldered contact points. Once everything is fitted into the project case, use a #1 Phillips precision screwdriver to fasten the screw and the case covers together. At this point, you need to test your finished trigger once again. As careful as you were putting the case together, it is possible for a fragile soldering contact to break loose. You don't want to wait and find out that your remote trigger is not working when you are out in the field.

Making a Delay Trigger

You are probably already familiar with a delay trigger. You use one whenever you place your digital camera in front of a group of people, set the 10-second timer, and run into the scene yourself. Or whenever you want to shoot a self-portrait, such as that shown in Figure 1-15. Most decent cameras on the market have pretty good built-in self-timers. It's practically an industry standard to set them to 10 seconds. There are two reasons you might want to make a delay trigger yourself: First, you can make one in case your camera doesn't come with a self-timer; second, the built-in 10-second timer is either too short or too long for your needs.

I learned to build a delay trigger because I found through experience that the 10-second delay timer is simply not long enough for me to set up a perfect shot. As my photographic experience increases over time, my taste for the "perfect" shot also increases. I found myself taking from several minutes to several hours just to perfectly set up a scene and all the models. When I have to join the scene myself, the setup time for each shot far exceeds the 10 second allowance.

Just recently, I visited the Villa Riviera building in Long Beach, California, and I had a chance to shoot some wonderful environmental portraits of my girlfriend and me. I had to set up my Canon EOS D30 digital SLR on the other side of the courtyard. For each shot, I set the 10- second timer, ran to the other side of the courtyard, and tried to pose before the timer went off. Each time I failed. After taking five unsuccessful frames, I finally gave up.

Without my further rambling, let's start making a delay trigger.

Parts You Need

Here are the parts you will need to complete this project:

* 555CN Timer IC (276-1723) or TLC555 Low-Power CMOS Timer (276-1718)

* SPDT Micromini 5VDC Relay (275-240)

* Pushbutton normally closed Momentary Switch (275-1548)

* 4.7K ohm 1/2W 5% Carbon Film Resistor (271-1124)

* 2200µF Electrolytic Capacitor

* 0.01µF Polyester Film Capacitor (272-1065)

* Heavy-duty 9V Battery Snap Connector (270-324)

* SPST Submini Slide Switch (275-409)

* Stereo 3/32" Submini Phone Jack (274-245)

* 6" Matching Solderless PC Board (276-170)

* Project case

* 9-volt battery

Tip

These are all fairly basic electronics parts, so they can be found easily at your favorite electronics store. I bought them all at Radio Shack, either locally or online. For your convenience, I have listed their Radio Shack part numbers.

(Continues...)

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Excerpted from Hacking Digital Cameras by Chieh Cheng Excerpted by permission.
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