Viewing Stereo Photos
There are two problems with stereo photography. The first is making the photographs. The second is viewing them. The principle behind stereo photography is that we have two eyes and each eye sees a slightly different image. The brain interprets these slight differences as depth. Stereo photography utilizes this principle in order to fool our brain into thinking we are seeing a scene in depth. In making a stereo photograph the photographer makes two images, one for the right eye and one for the left eye. The problem is in showing the right image to the right eye and the left image to the left eye. Since stereo photography was invented (around the time photography was invented) many methods of viewing have been utilized from the old wooden Holmes stereoscope (invented by Oliver Wendell Holmes in 1860) to the latest 3D TV. For the purposes of the internet there are 3 methods commonly used for viewing. These are 1) the parallel format, 2) the cross-eyed format, and 3) the anaglyphic format. I will talk about ways to view with each of these formats.
Parallel - This format has the right image placed on the right side and the left image placed on the left side. There are a very few people who are able to view the right image with their right eye and the left image with their left eye with no equipment (this is called free-viewing). This is very unnatural because our eyes are not meant to diverge their viewing paths more than parallel, which would be necessary for images larger than the normal eye separation (approximately 2.5"). In order to view these images one must look through a device which essentially separates the eyes, as through two horizontal periscopes. There are a several of this type of viewer which can be purchased from Steve Berezin. One of the most convenient is called the 3D Scope. With it you can view any medium-sized stereo image on a computer screen. The major disadvantage is that if you are wearing glasses you have to move back a little with from the eye opening because the glasses won't fit. Another type of viewer which doesn't have this problem is called the Wheatstone Mini-Scope. Another possibility is called Adjustable 3D Prism Glasses. The problem with these is that you have to move too far away from the screen. There are several other possible viewers sold by Steve Berezin. He also has a viewer selection chart to help you decide which viewer is right for you. I will also mention that I make a viewer which will also work for the computer screen, but it is really intended for viewing images which are a little bigger (10" wide images, 20" pairs). It is called the Hyper-View viewer and is also available from Steve Berezin.
Cross-Eyed - This format features stereo images which are reversed from the parallel format. That is, the right image is on the left side and the left image is on the right side. In my opinion this is the most preferable format for viewing on the computer screen, if you are able to do it. The procedure is to cross your eyes so that you are seeing the image on the left side (right view) with your right eye and the right side (left view) with your left eye. Many people can learn to do this. I will explain a very simple method for doing it.
1. Open one of my cross-eyed views (the image "Doors, Fort Point" works well).
2. Sit with your face about 2 feet or more from the computer screen.
3. Hold a pencil a few inches from your nose.
4. While looking at the image notice that you will see two images of the pencil.
5. Move the pencil forward and back and/or side to side until you see the pencil point in the center of each image.
6. While carefully holding your head and the pencil still, converge your eyes on the pencil.
7. When you see the pencil as one image slowly notice the stereo image behind the pencil.
8. Slowly change your focus from the pencil to the image.
9. With practice you may be able to do this more and more easily. When you feel comfortable you can move closer to the screen.
If it is uncomfortable for you, do not do it.
Anaglyphic - This format is the easiest to use. However you must have the anaglyphic glasses. There are several slightly different types. The ones that work the best for these images use red and cyan filters. Red for the left eye and cyan for the right. Simply hold the glasses in front of your eyes and look at the image. The image is not as pristine as with the other methods, but it is easy and inexpensive. If you do not have the glasses and would like a pair, send me your address and I will send them to you free of charge.
Parallel - This format has the right image placed on the right side and the left image placed on the left side. There are a very few people who are able to view the right image with their right eye and the left image with their left eye with no equipment (this is called free-viewing). This is very unnatural because our eyes are not meant to diverge their viewing paths more than parallel, which would be necessary for images larger than the normal eye separation (approximately 2.5"). In order to view these images one must look through a device which essentially separates the eyes, as through two horizontal periscopes. There are a several of this type of viewer which can be purchased from Steve Berezin. One of the most convenient is called the 3D Scope. With it you can view any medium-sized stereo image on a computer screen. The major disadvantage is that if you are wearing glasses you have to move back a little with from the eye opening because the glasses won't fit. Another type of viewer which doesn't have this problem is called the Wheatstone Mini-Scope. Another possibility is called Adjustable 3D Prism Glasses. The problem with these is that you have to move too far away from the screen. There are several other possible viewers sold by Steve Berezin. He also has a viewer selection chart to help you decide which viewer is right for you. I will also mention that I make a viewer which will also work for the computer screen, but it is really intended for viewing images which are a little bigger (10" wide images, 20" pairs). It is called the Hyper-View viewer and is also available from Steve Berezin.
Cross-Eyed - This format features stereo images which are reversed from the parallel format. That is, the right image is on the left side and the left image is on the right side. In my opinion this is the most preferable format for viewing on the computer screen, if you are able to do it. The procedure is to cross your eyes so that you are seeing the image on the left side (right view) with your right eye and the right side (left view) with your left eye. Many people can learn to do this. I will explain a very simple method for doing it.
1. Open one of my cross-eyed views (the image "Doors, Fort Point" works well).
2. Sit with your face about 2 feet or more from the computer screen.
3. Hold a pencil a few inches from your nose.
4. While looking at the image notice that you will see two images of the pencil.
5. Move the pencil forward and back and/or side to side until you see the pencil point in the center of each image.
6. While carefully holding your head and the pencil still, converge your eyes on the pencil.
7. When you see the pencil as one image slowly notice the stereo image behind the pencil.
8. Slowly change your focus from the pencil to the image.
9. With practice you may be able to do this more and more easily. When you feel comfortable you can move closer to the screen.
If it is uncomfortable for you, do not do it.
Anaglyphic - This format is the easiest to use. However you must have the anaglyphic glasses. There are several slightly different types. The ones that work the best for these images use red and cyan filters. Red for the left eye and cyan for the right. Simply hold the glasses in front of your eyes and look at the image. The image is not as pristine as with the other methods, but it is easy and inexpensive. If you do not have the glasses and would like a pair, send me your address and I will send them to you free of charge.
