For some time now I've been interested in stereoscopic imagery. I'm going to tell you all about it.
Before I begin, let me offer this disclaimer: there are likely all sorts of rules and standards to follow when creating stereoscopes professionally, but I don't know about them. This is all just stuff that I've discovered on my own. Much of it could be incomplete or completely wrong for all I know, but what you are about to read is what makes sense to me.
STEREOSCOPES: WHAT THE HECK ARE THEY?
A stereoscope is an image that, when viewed in a certain way, appears to be three dimensional. This image is usually composed of two smaller images, placed next to each other.
As most folks know by this day in age, seeing in three dimensions is possible because we (generally) have TWO eyes. Our eyes are set apart from each other, and this allows us to see two slightly different views of our surroundings. Using these two views, our brains are able to figure out how far away something is.
Our brains are very good at this, as they have been doing it since we were born. However, we can trick our brains. Stereoscopic images rely on doing so.
STEREOSCOPES: HOW DO I OPERATE THIS DARN THING?
If you have ever used one of those "Magic Eye" things that were so popular in the 90s, then you have a head start at stereoscopes. They are, in fact, the same thing.
The idea behind a stereoscope is to make your left and right eye look at different images. These images simulate the views that your eyes would see while looking at a real life scene.
This is easier said than done, as your eyes aren't used to doing this. They will naturally try to focus on one thing at a time. You must somehow trick your eyes.
One of the most popular ways to do this is to put your face very close to the image, preventing your eyes from looking at the same thing. While maintaining your eye position, slowly move away from the image, and your eyes should see the two images fuse into one. This is called "free fusing."
I have much more faith in you than this. I think that you can, and have free fused before without rubbing the skin off of your nose. Have you ever looked at someone, allowed your eyes to unfocus, and found that your subject appeared to have three eyes? Most people I know have done this at one point or another. Try the exercises below.
If you can do the exercise above, try free fusing the next image.
The mountains should appear farthest back, then the square, then the small point. The line to the right should appear to project forward from the horizon.
If you are able to unfocus your eyes, but can't get the images to cross over each other, try sitting farther away from the screen. Because you are making your eyes point outwards, if you sit farther from the screen, you won't have to force them out as far. This will always apply to this type of stereoscope.
If you can't get it to work, keep trying; practice makes perfect!
If you REALLY can't get it to work using either method described above, here's another method:
Get yourself two empty paper towel tubes. Place the first one against the right image, and against your right eye. Place the other one against the left image, and against your left eye. This will filter out all of the distracting surrounding images, and let your brain focus on only the two images you are providing it.
Keep trying, but give your eyes a break every once in a while. This is hard work if you haven't done it before, and you don't want to pull an eye muscle!
STEREOSCOPES: CAN I MAKE MY OWN?
If I can make my own stereoscopes, then you surely can. All you need is a camera. Ideally a digital camera and access to Adobe Photoshop is best, but you can do it with a traditional camera and printed photos.
-Taking the Photos-
1) Figure out what you want to take a stereoscopic photo of. Make sure it's something with depth to it (for example, don't take a picture of your wall. That's not going to do anything). I like to take pictures of my room, as there's plenty of clutter there to give us an idea of spacial arrangement.
2) Pick a focus. A table, a chair, a doorway, a vase, whatever. Just make sure that you pick something that you will center and focus on for both of your photos.
3) Take your first photo.
4) Now move slightly to the left or the right. It doesn't really make a difference, so long as you are able to arrange them properly later on.
5) Focus your camera on the same thing as before. Your viewfinder should show almost the same picture. Most of the same elements should still be visible in most scenarios.
6) Take your second picture.
-Arranging the Stereoscope-
7) Develop/upload your pictures.
8) Place your two photos side by side. It is best if you can put them together so that there is no gap, as that is less distance for your eyes to travel.
9) Try to free fuse the images. If you are having trouble, try positioning yourself farther from the images, or shrink them down on Photoshop. The smaller they are, the easier it will be.
10) If you can free fuse the images, but they look very strange, try switching them. They need to be placed in the right order, or else they won't work.
11) Try any of the hints from above to help you free fuse them.
SOME THINGS TO LOOK OUT FOR
When your are taking stereoscopic photos, avoid the use of the flash. It is very important to keep the setting as constant as possible, and the lighting has a very large effect on this. Free fuse the image below, paying close attention to the shadows.
You may notice that the shadows appear to be attached to the object casting them, instead of stuck to the surface they're being cast upon. This is because the light source emitting the light has moved. To avoid this, make sure that your flash is off, and your light source is separate from the camera.
Another point to watch for is the distance between your photos. Generally, to create a believable stereoscope, you can position your camera shots about two to three inches apart. This is about the distance between your pupils. However, if your subject is very large or very far away, you may want to space your shots farther apart. This is so that your eyes can get a better look at the subject. For example, the following stereoscope is the view from my apartment balcony. The two shots are about ten feet apart.
If your subject is very small and you are close to it, you should only move your camera a small amount. Otherwise, your eyes will not be able to cover the distance between the images. Even if they do, the images will be so different, your eyes won't be able to connect them.
STEREOSCOPES: THE DIGITAL REALM
An interesting idea is to apply these same principles to three dimensional environments other than real life. For example, video games. Because the camera-environment relationship acts in the same way, we can apply the same principles to video games in many cases. A few examples I have created follow.
World of Warcraft:
I find the World of Warcraft ones work best.
DRAWING YOUR OWN
If you want to, it is possible to draw your own stereoscopes. This is not an easy task, and requires a fairly strong understanding of the way stereoscopes work. You should pay attention to the following rules:
1) The closer something is to you, the more it will shift between the two images.
2) Your eyes are able to move independently on a horizontal plane fairly easily, but not on a vertical one. Do not shift images up or down, as your eyes won't be able to fuse them.
3) Start simple.
4) Be precise. Use rulers, protractors, compasses, etc. Your eyes are very fussy, and you need to make the images read as clearly as possible.
5) BE PATIENT! It may not work at first, but try again.
I hope this has been interesting to read. Good luck on your adventures in the third dimension!