ILLUSION — Optical Illusions

Stereo photo or convergent stereopairs

If you can put an eye in a pile, then you can move right to stereoscopic pictures observation. If you don’t then we recommend you to learn the technique of 3D-photos watching at first. If you want to go on with stereo images, then welcome to our gallery of stereoscopic illusions.

Stereophotography is a picture of some objects on paper or screen that gives understanding about their location toward the observer and each other. Plane photo can’t describe the distance between objects. All the pattern combined filming of pre-computer age is based on this space.

Sergey Elizarov

Sergey Elizarov was born in Moscow in 1967. He’s got a wife and a little daughter. Finished 2 institutes and worked as a pastry chef and a coffee-machine exploitation engineer. Now he is a free kid photographer. He works professionally at stereophotography and shared some of his works with us specially for our web-site. Every picture is a convergent pair, where there are separate images for both eyes. Lots of people can’t learn to watch these pictures, but we hope you can.

Just a picture is not enough for us, stereo-photographers. Our cameras see the world with two eyes. We capture events in 3D.

Let’s have a little lesson to learn how to watch convergent stereopairs.

So, how to learn watching convergent stereopairs?

 

When adults find out the existence of stereography, they encounter serious problems while watching convergents. After 15 minutes of unsuccessful tries they get disappointed and give up, having never seen a full 3D picture. Partly the difficulties lie in undeveloped power stroke of an eye crystalline lens, responding for eye focus. Because we have to spend much time at the computer screen of reading our eyes have to focus at objects at the distance of 0.3-0.7 meters all the time. That’s why our muscles that change the crystalline lens curve work weakly and with time our eyes lose the ability to adjust fast.

Another reason of convergents watching difficulties deals with brain viewing habit, that’s being formed during the entire life. The matter is that our brain keeps some kind of a parameter table connecting the angle between eyes’ watching axis and the curve radius of crystalline lens. When we observe landscape objects located at the horizon, eyes’ axis are almost parallel (the angle between them is close to zero). Looking at a close object that is in about 25 cm we put eyes’ axis to an angle of about 15 degrees. Our brain has formed some kind of a conditional table, where every possible angle value has its muscle strain parameter at which eye forms a sharp image of a “targeted” object. To see the convergents, we need to break free from the strict rules of the table we got used to, because the needed combination of eye muscle strain and axis angle is never used in everyday life.

Picture 1. Now let’s make both eyes’ crystalline lenses work hard, alternately adjusting sharpness at the pencil… — the clock will be doubled

Picture 2. … and then at the object – the hand with the pencil will be doubled.

Let’s have a little practice, which helps to break free of the limits of the table we got used to. Find an object that is removed at 3-4 meters from you. Take a pencil in your left hand and put it before yourself at the line “left eye – object”, and at 25-30 cm from your eye so that you could sharply see the pencil. Now let’s make both eyes’ crystalline lenses work hard, alternately adjusting sharpness at the pencil (Picture 1 — the clock will be doubled) and then at the object (Picture 2 — the hand with the pencil will be doubled). This exercise trains our left eye to adjust sharpness not changing view direction. The same exercise should be done for the right eye. Put the pencil in the line “eye–object”. This is useful to cure and prevent myopia and hypermetropia. Keep doing this exercise for 1-2 minutes for each eye several times a day to work them out. After this you can go to watching convergents using mask.

 

To make a mask you’ll need a piece of cardboard or thick drawing paper. You’ll need to cut out a rectangular mold about 20×15 cm in size. There’s no need to give exact parameters. Our task is to get two paper corners, that form together shape like “|_|” and are connected with clips (Photo 3 depicts, how to cut out a mask). Put yourself at 1 meter from your screen. Take the mask in your hand at 25-30 cm from your face, the hole is about 4.5 cm. Now we need to adjust the hole between “trotters” and the distance between the mask and the eyes so that the right eye could see only left half of a stereopair and the left eye – the right half. It’s easy to do alternately closing one eye and then another. Picture 4 shows the location of observer, mask and screen.

Picture 4. Location of an observer, a mask and a screen.

Picture 5. When you open both eyes and focus at the screen you’ll see a picture like this.

Now focus at the mask (you can write something on it to make it easier). Two halves of a stereopair will converge into a blurry one. (Just as it is at the Picture 5)

Picture 6. For some time your eyes will be adapting to the unusual situation and with time the picture will grow sharper and the mask will be blurry.

Slowly move your attention to the center of the blurry stereography in the mask hole. For some time your eyes will be adapting to the unusual situation and with time the picture will grow sharper and the mask will become blurry (Picture 6) and after that you can see clear stereo-effect. As it is your first time, your view might fall back as it is shown at the Picture 4 but with time you’ll learn to watch convergents and move your “point of attention” all over the picture not losing sharpness and strain that keeps your “sharp” attention at the picture. With time your brain will update its table with new eye-angle-to-muscle-strain combinations and you won’t need this mask any more.

Do the instructions with the mask described above to master the method of watching stereopairs at screen. Train your eyes and you will see stereo convergents for sure.

Strereo photo — Convergent peach.

Now you are ready to take a look at Sergey’s works.

Click the stereo photo to enlarge.