Digital photography is nice in that you don’t waste any film when experimenting. Some people have developed the ability to see Stereopticon pictures without the need for a Stereopticon Viewer.
A Stereopticon is an old fashioned picture viewer where you put a photocard with two pictures of the same view on it in the far end, and look through the lenses at the near end to see a scene in 3d.
I learned how to view those without the ‘viewer’ years ago.
It involves tricking your eyes into looking far, but focusing near.
In other words your left eye focuses on the picture on the left, while your right eye focuses on the picture on the right. An alternative is to cross your eyes and then focus, but then the 3 dimensionality is inversed so that objects that are supposed to be far in the images appear near, and near objects appear far. (I can’t seem to do it that way.)
[pic is adjusted to 550 pixels wide on a pc screen which makes it easier to view in 3d, it may not work as well on your iphone or tablet]
One key to doing this is to have the images close enough together which eases eye strain. If you look at the image above and relax until you see three images, then all you need to do is focus in on the middle image. The one in the middle is the one which is seen by each of your eyes independently, and thus when in focus is a pseudo-stereo image and will ‘pop’ from the page(screen). You perceive depth due to the slight offset between the two images. I decided to try this today with a Smokey Quartz Geode(Keokuk variety) from my Geode collection. I must say I do like the results! -Andrew