Taking Photos

 
 

Basically to make a stereoscopic image you have to take two photographs from slightly different positions.


Single Camera

You can do this quite simply with a single camera by taking one picture than taking a small step to one side and taking another. This is known as the stereo shuffle. The trick is to make the movement small and not to rotate the camera between the two shots. The other restriction on this is nothing has to move between the two shots so this technique is restricted to still life objects and landscapes. One way around this is to get a special prism to put in front of the lens of your camera, to give you two images on the one piece of film or digital shot. These are not made for all cameras and tend to be expensive, they also produce only half the resolution in the final image due to there being two pictures side by side.


Twin Camera

This is either a single camera with two lenses or two cameras mounted together. There are some film cameras that can take two pictures at once, these were mainly made in the 50’s and sometimes appear on ebay, there is a modern manufacturer of a stereo film camera but it is very expensive. There are some Japanese “fun” cameras with two, four and even nine lenses, these are film cameras and there is normally a small delay between each lenses being used, so the subject of your photograph must be still for a time. There is, of yet, no manufacturer of a digital stereo camera. The cheapest solution is to get two low cost cameras and mount them together side by vertically in a portrait aspect. This will normally allow the correct interocular distance to be set up. However, many cameras have the lens at one end and so you can get a landscape alignment by turning one of them upside down and mounting them end to end. There is the problem of taking the photographs at the same time and digital cameras are notorious for the shutter lag, that is the time taken between pressing the shutter and taking the photograph. I have found the best way is to partially hold down both shutters until they both show they are ready to shoot, and then press them simultaneously. However, fast moving targets are not always guaranteed to not show differential movement between the two images. The shutters in some cameras may be simply wired together to ensure they fire at the same time, however the electronics on most mean that there needs to be some extra electronics required to synchronise them. Even then, synchronisation is likely to be only within 1/30 th of a second.


Interocular Distance

However you take the images, the distance between the lenses taking the two photographs is known as the interocular distance, and in most cases, should be the same distance as that between your eyes. If they are further apart then the stereoscopic effect is enhanced, this is sometimes done deliberately for some distant or large objects like buildings. However, the downside to this is the lilliput effect where it seems as if you are looking at a model of the object rather than the object itself. This is because you brain is telling you that you don’t normally see that much disparity between the two images. Conversely for close up macro photography the separation of your eyes is too great and this must be cut down. This is often physically impossible using two cameras and you have to resort to shifting a single camera or using prisms or mirrors.

Getting your stereoscopic image