Over the past nine years we have modified a few cameras for use on balloon payloads. The idea is to solder wires to the picture taking button so that when they are shorted together the camera can take a picture.
Film cameras tend to be mechanical devices, but in the mid 1990’s the Advanced Photo System (APS), was introduced. It was developed as a cooperative effort between Canon, Fuji, Kodak, Minolta, and Nikon, This introduced electronic control to consumer cameras with electric motor film advance and and an electronic switch for taking pictures.
Our first camera, an APS was modified for a spring 2005 balloon flight. It was triggered by an electronic timing circuit closing a relay to short the camera switch and take a picture. Because film is limited to 36 pictures, the time interval was set to about four to five minutes to cover a 2 1/2 hour flight. As digital camera’s became less expensive and more lightweight and compact, it was easy to convert them, opening up the opportunity to take hundreds of photographs during a flight.
Opening a camera body and soldering extra wires to its circuit board voids the warranty. There is a possibility of making a mistake, and destroying the camera. Also, there is some possibility of losing the balloon payload during a flight. So, like with the Stock Market, don’t invest more than you can afford to loose. Disclaimer: This is a great way to destroy a camera, don’t blame me if you succeed! Also, this is my best effort to anticipate what you may encounter, but your camera may be different!
Most camera’s today close two switches to take a photograph. The first, half pressed position, activates the electronic focus and light metering to determine exposure settings. This permits framing one potion of a scene, perhaps a dark portion, then changing to the framing actually desired, to ensure detail is shown in the dark portion. We don’t need that for landscape photographs from a balloon. I look for a simple snapshot camera, that uses only one switch to take the photograph. In the past, some simple cameras used an additional switch to select landscape or closeup mode. Now this usually done from a camera menu.
Dismantling The Camera
fine insulated wire, 26 or 28 gauge
soldering iron with a fine tip
two, three or more, jar covers to hold small screws off the floor.
Small tip (jeweler’s?) Phillips screw driver
fine drill bit, about 1/16”, to drill a hole big enough to run two wires through.
needle nose pliers
Optional: a close up camera to document how to take the camera apart.
Optional: handheld Voltmeter, on the ohmmeter setting
Step 1- Remember how things come apart, so you can put them back together.
Step 2- Remove batteries, and memory cards.
Step 3 – Start taking screws out of the camera body, Note their length, whether they a flat (countersunk) or rounded, whether they are different sizes. They are probably all the same (flat), except maybe for length, but now is the time to note any differences. Put the screws in one or two of the jar covers. There are probably four or five, on the sides and bottom. There may be one in the battery compartment. There is usually one under a sticker, to determine if you have voided the warranty by taking it apart. Face it. You are voiding the warranty. When a screw falls on the floor, look for it as soon as possible. On a tiled floor, you can sometimes find it by setting one eye near floor level to took around for things sticking up from the floor. You will often be surprised by what you find. I have no advise for looking around on a rug, except persistence. When you lose a screw you will have to decide which position is least important.
Step 4- Separate the camera body, There may be a spring loaded cover for the batteries, so be careful of that. There may be switches through holes on the case. They are probably through the main part, but be slow and careful anyway. Usually the circuit board is screwed to the button panel on the back and the front, lens side, comes off.
Step 5 – Usually the contacts for the power and picture taking buttons are on the back, but look around at this point anyway. There may be a plastic top piece that detaches, exposing the power, and picture taking switch. But there are probably not solder contacts.
Step 6 – There a rocker panels on the back of the camera that poke switches. I doubt there a springs but there could be. Be careful and slow.
Step 7 – If necessary, remove screws holding the circuit board to the back part of the case. It most likely is necessary. I expect four or five screws, note any differences. Here, there may be round cap screws.
Step 8 – Now separate the circuit board from the back panel. Some maneuvering of the circuit board may be necessary to pull switches through holes in the case.
Step 9 – Locate the switch and power solder points.. The should be a small circuit board on the top which receives pressure to close the power switch and the picture taking button. At the edge there should be three or four (or more?) solder points to the main board. The plan is to solder wires to two of these contact. However, finding which two is largely trial and error. For four contacts there are six pairs of connection possibilities. The four contacts are for two power switch connections and two picture taking connections. It may be possible to identify a circuit trace going to the switch. This would be one connection. It may be possible to use an ohmmeter to determine if two contacts are connected as ground. If this is the case either of these contacts could be used. So, take your best guess.
Step 10 – Solder two wires to two contacts. Strip and tin (wet with hot solder) the ends of the wires. One end of each wire should be about 1/2” for later use. The other end should be about the length of the electrical contacts on the main camera circuit board, perhaps 1/8”. They can be stripped and tinned a little longer, then cut to length. Use the needle nosed pliers to put a 90 degree, right angle, bend in the wire at the contact end. While not the correct way to solder, add a little extra solder to the stripped wire. Lay the wire so the short stripped end is on the contact and the wire is laying on the board going to the right. When the camera back is reinstalled the wire will have to avoid the switch contacts for the back buttons of the camera. Solder the wire to the contact by laying the wire on the contact and holding it down with the soldering iron. While not the correct way to solder , the intent here is that the solder on the tinned wire melt, and in turn, melt and combine with the solder already on the contact. Hopefully when the iron is removed the wire will remain, soldered on the contact. You may need to roll the length of wire laying on the circuit board to hold it on the contact as it cools. Check to make sure the wire is stuck to the contact. And repeat with the second wire.
Step 10 – Drill a hole in the camera body for the wires. Drill a small hole on the right (from the back) side of the camera, near the top. If there is an indentation here for the camera strap, that is a good place to drill the hole. This should not take a lot of force since the plastic is relatively soft.
Step 11- Feed the wires through the drilled hole
Step 12- Reattach the circuit board to the camera back. Depending on how much confidence you have in your connection, you may not want to reinsert all the screws, just enough to hold things together.
Step 13 – See if you can insert the batteries and memory card at this point to test the connection. You probably can’t at this stage. But its worth trying to test the connection without fully re assembling the camera.
Step 14 – If necessary re-insert the top case plate and reattach the front of the case. Make sure the battery compartment door is in place before screwing on the front of the case. Use as few screws as needed.
Step 15 – Test the connections:
a) insert batteries and memory card.
b) Does the camera turn on? If not, Oops!
Are Batteries in correctly?
Is the Battery case door attached correctly?
Is one on the new wires interfering with the power switch
Did the Power switch circuit connection become desoldered when the wires were attached?
Are the case buttons misaligned with the switches? More care might be needed when reassembling the case.
It is possible a component to fried by the solder heat and the camera is now dead. I’ve never seen this done but it is a possibility.
c) Try to take a picture the normal way, push the take picture button. If not,
Is one of the wire new wires interfering with the button action?
Has the circuit connection become desoldered?
We were only going to fly this on the balloon, weren’t we? We may not “need” this feature.
d) Try to take a picture by shorting the wires together.
If this doesn’t work try a new connection, or set of connections. There’s only five more combinations to try, right?
Step 15 – If everything works, disassemble the camera enough to finish inserting all the screws, and do a final reassembly of the case. If nothing works, Try disconnecting the wires you just added, maybe try adding a little more solder on the circuit board connections and reassembling the camera. If the camera now works you can try attaching the wires again.
The wires can now be connected to a relay to control remote picture taking.
Paul Verhage, at nearsys.com, offers an inexpensive camera modified in, what I presume is, this way.
There is a hacking project for Canon Cameras, CHDK, Canon Hack Development Kit. This allows you to take over and program the microprocessor built into the camera. Among the available programs is an intervalometer. The camera can be programed to take pictures every few seconds. Check the list of compatible cameras.
Perhaps in a future post I will discuss a circuit for connecting to a relay activated by an Arduino or Parallax Basic stamp.
© David B Snyder 2013