Introduction: The WedgeCam- a Camera Obscura for Your Scanner
Do you have a scanner that’s just collecting dust. We have come up with a great simple and fun project to convert this mundane device into a strange and wonderful digital camera. Hit the scan button and wait patiently (or not) to get an eerie looking digital picture appearing on your computer. Not so still? Then you get an range of warped effects, with everyone wondering how they were made.
Step 1: Background
This step is really just a bit of the story on how this particular design came about. Feel free to skip this step if you want to get on with the making.
Camera Obscuras for scanners is not a new idea, I remember seeing this one on Make a while ago:
All the ones I had seen had to have a small thin type of scanner, with the whole scanner tipped over and the camera obscura bit pointing straight out. Making this type of camera obscura wasn’t as convenient, and the scanner I had was a bulkier printer and scanner combo.
There must have been a way to get the image to the scanner plane without having to flip your scanner, and the solution came in the form of a mirror held at 45 degrees to reflect the light coming in down to the scanning bed. My first camera obscura wasn’t a wedge shape, it was a box which had a cardboard ‘bracket’ holding the mirror at the 45 degrees in the middle of the box. I had a suitable lens (magnifying glass) but felt that I needed a way to adjust the shallow focus it produced, and bring the focal point closer to the scanner. A roll of tape had just run out and was perfect to fix to the front of the box. I cut a slit in it so I could easily slide the handle of magnifying glass in an out to adjust the focus.
It worked great at home and I took a cool picture of myself with wavy arms. I was so excited that it worked that I took it to my local hackspace, Create Space London (http://createspacelondon.org/). I tried to fit it onto the scanner there but much to my disappointment it didn't fit. The lid of the scanner printer combo was designed so the lid didn't go much past a 45 degree angle and was also not detachable. Rather than give up on the notion and leave defeated, I decided to chop the back edge off as it served no purpose and the WedgeCam was born. I took many pictures with it of many people that use the Create Space.
Step 2: What You Will Need and Choosing the Right Lens:
You will need:
-Access to a scanner.
-Some A4 paper for measuring.
-Cardboard, or a cardboard box.
-A lens, or magnifying glass, (you will need to check if it meets the requirement).
-A small mirror, (the lighter the better, acrylic works well).
-Scissors, Gaffer or duct tape (optional plus: double sided foam tape).
About the lens:
Your lens can be a made of glass or acrylic. As this is going to be hanging off a bit in front of the WedgeCam, its best to find a light one. A big lens can gather more light but your resultant image would have a shallower focal range or smaller depth of field. I like the shallow depth of field as I think it produces nicer pictures, although I must admit it is quite hard to find the focal point.
The most important bit about the lens is choosing one that focus an image from where you expect to stand to the scanner. It needs to project an image of something kept a distance of 1-2 meters in front of the lens, a distance of about the width of a piece of paper (210mm or 8.3in) behind the lens. The light coming in from the lens travels about the distance of half the width of A4 paper to get to the mirror, is reflected 90 degrees and then travels another half a paper distance to get to the scanner bed.
To find your focal distance find somewhere with a bright light source like a TV and grab your lens and a piece of paper. Dim the lights in your room and hold the lens in front of your tv the same distance you'd expect to be in front of your scanner when you would take the picture. Now move your piece of paper closer and further from the lens until your can produce a clear image on the paper. Get a friend to check if this distance is about the width of A4 paper. It can be a bit longer but not too long, else your lens barrel might be too long to be stable on the final WedgeCam
Step 3: Making the Cardboard Shapes
The shape of the WedgeCam is simple and can be made using the dimensions of an A4 piece of paper. The image above gives you an idea of the overall shape. Make each shape separately if you can’t make it on one piece of cardboard.
The front is the size a piece of A4 paper. The sloped back square piece has a lengths the same as the longest side of an A4 paper. The two sides are like an A4 paper creased as a right angle triangle. Mark a line on the front panel linking the opposite corners so you can find out where the middle is. You can use the paper and Mark around it to get the shapes.
The lens barrel is a bit tricky, here we used a strip of card and creased it to make it bend around the lens easily. If you have a magnifying glass then it's handy to keep it for adjustment, in this case you can make a slot on one end of the strip for the handle.
The length of the strip must be a bit bigger that 3.14(pi) times the diameter of the lens. You can secure the lens in the new tube with tape. It's width would depend on your lens but 10cm should be enough.
With the new lens tube you can make a hole in the front card in the middle by drawing around it and cut it out.
Step 4: Assemble It!
You can tape all the panels you made together using tape along the edge. A thick dark tape is good to stop more of the light from leaking in. Fit the lens tube in the hole you made but don't tape as you may want to adjust this later.
You can use double sided tape to stick your mirror to the inside of the back panel. Try get it as close as you can to the middle.
It should be ready to stick on your scanner and scan.
Step 5: Scan You!
Find a scanner program on your computer, maybe one came with your scanner or more likely than not your computer has one already in there.
Once your scanner software is open, lift the bed lid and place the open side of the box against the glass, and the lens toward the subject. Click preview (or something equivalent) in your software and try and make out what it's seeing. Play around with different lighting and lens tube positions until you find out how its focusing on the bed.
Tip: Counter intuitively moving the lens towards the subject moved the focus plane closer to the scanner.
Once you got a good idea of the image it would take then you can hit scan.
Most modern scanners I tried would produce only black and white images when using this due to the way they acquire colour information. These have Red, Green and Blue lights that shine in sequence and the information is used to interpolate the colour. As this light from the scanner can't get to your subject that colour information is lost.
You can now experiment, see what happens when you scan and move in different ways.
Thanks to Mark https://www.instructables.com/member/Cogtoys/ for helping me with this instructable (sorry I took so long)