Opening a single use 35 mm camera
On September 27/28 of 2003, all blood donors in The Netherlands were invited to visit one of 5 zoos. We (my 9
year old daughter and I) were lucky enough to get tickets for the saturday (27-09-2003). It was a fine day and
all people were treated to a real party. I expected to go to a zoo and that's it. But it wasn't.
As soon as we passed the gates, we got lots of presents:
Warning and disclaimer
Now, let's go to the pictures and see how this little beast was constructed.
On the right, you see how it looks like when you undress the camera. In most cases, the dress is a piece of
thin cardboard with some fancy name on it.
The black blob in the upper section of the picture is the actual camera. Since it is matte black, it was very hard to make pictures of. So please interpret the pictures instead of absorbing them.
In the bottom section you see the cardboard envelope. It has holes for just about everything:
The same stage in the opening of the camera, but now with a full frontal shot of the camera. You see that the
thing is dull black, so I had to increase the contrast and now the colours look like dung.
You can easily see the flashtube, the flashcharge button, the viewfinder and the lens. Now it's our task to see how to open the camera body. We're here to harvest parts which otherwise could well end up in a landfill.
Finding the retainer clips.
We're going to inspect the sides of the plastic camera body. In my case, the two parts of the black shell were
held together by means of small plastic retainer clips, like you see in the picture on the right:
There will be several of these clips around the perimeter of the camera body. You should find at least 4 to 6 of them and use small matchsticks or screwdrivers to force these clips open.
Another way it to use a small hobbyknife or a Stanleyknife and just cut away the locking parts of the clip. We're here to salvage parts, not to reload the camera with a new film. So we only need to open the shell, no more.
The top is off.
After you have found the retainer clips that keep the two parts of the shell together, you get a sight as seen
in the picture on the right. My single use camera had a flash inside, so it also had lots of electronics.
That's why you see the green printed circuit board around the lens assembly.
Going from top to bottom we see:
Full frontal nudity.
This is a close up of the front of the camera (top lid removed). The contrast is terrible, but it's the best I can do. If you want to see more:
The flash compartment.
What you see here is the battery compartment. It's no big deal. See the long copper strip? It's there to connect the positive side of the battery to the printed circuit board.
The flash synchronisation unit.
On the right, you see the flash synchronisation of the camera. As we know, a flash is very short. It's
duration is in the order of milliseconds. So if the flash triggers when the shutter is not fully open, you get
a partly exposed picture. Not what we're after.
So 'real' camera's have one fixed flash-time, mostly labeled 'X' or marked in red on the shutterspeed dial.
We don't have a shutterspeed dial, but we do have a shutter of variable speed and we still need a synced flash.
In the center of the picture you see two contacts. When these are pushed together, the flash fires. The upper contact is pushed down by the little 'finger' just above it (on the left). When the shutter is fully opened, the finger has pushed the upper contact on the lower contact. It does so because the finger is integral part of the shutter blade. This is a masterpiece of engineering.
Front of the shutter.
In the picture on the left, we see the shutter module taken out. You must first find the retaining clips that
fixes the shutter to the bottom shell of the casing.
After you have released the clips, the shuttermodule can be taken off. And this is what you will get.
If you look careful, you can see the aspheric curvature of the lens.
In the top left you see the filmtransport, the shutterspring tensioner and the double exposure prevention. It's all inside the white assembly right under the serrated ring.
Backside of the shutter.
In this picture we see the backside of the shuttermodule. In the top right section we have the filmtransport
unit (with double exposure prevention).
The rectangular space below the viewfinder is the backside of the lens assembly. You cannot see the lens since it is covered by the shutter blade.
This shutter blade swings down and up again. When the blade is fully down, the finger (see above) is fully down too and the flash contact is closed. If the flash capacitor has enough charge in it, it will fire. If not, the flash will remain dark and that's it.
There is one funny aspect here:
Here we see an overview of the camera with the top shell, shutter module and flash module removed. From left to right we have:
Where the film is loaded.
The film transport "plane".
In the picture on the right, we see the film transport in close-up.
What you see here is the exposure frame, seen from the side of the lens. So we look now, as the light would normally travel towards the unexposed film.
Look carefully how the film is transported through the body. Do you see the curved slot? That's where the film is moving through.
But why is this slot curved? You understand why this is so by looking at the lens. The lense is aspheric, but it's a single component lens. So it still has lots of aberations, one of which is a curved focal plane...
And that's why the film is kept curved: it will correct for unsharpness in one direction. The mechanical engineer solved part of the problems of the optical engineer by curving the filmplane under the exposure mask.
On the left, we see an overview of all the harvestable parts of the single use camera. Due to the special exposure, you can now look inside the storage canister for the metal film cartridge. Deep inside this cavity, you can see a round thingy. This is the drive for the winding spool inside the film cartridge.
You've now seen what I found inside a single use camera. These small single use machines contain lots of parts
that can be used for science projects and possibly too for robotics.
Now go out and get yourself a used one-way camera and salvage the parts you need. Wake up the child inside you and dare to ask: How on earth did they realize that in a dirt cheap package?
Page created September 2003,