More Technical Stuff

Taking Stereo Images

Composition; the old adage that you want something of interest in the foreground, something of interest in the middle ground and something of interest in the background applies equally to stereo photography as to flat photography.  If you follow this advice your stereo images will really come to life.  Viewing correctly aligned stereo images is just like being there; you see the image exactly as you saw the view when you pressed the shutter.

First a couple of simple rules; The 30 to 1 Rule.  If you include a subject at infinity, the minimum camera to subject distance should be 30 times the lens separation.  If the cameras are at 65mm lens separation, the closest subject should be no closer than 2m. 

If you do not include a subject at infinity, the minimum camera to subject distance can be reduced to 15 times the lens separation, (The 15 to 1 Rule) ie 1m for a 65mm lens separation, but do not include anything in the image that is more than 2m away from the camera, as this may cause eye strain when projected.

Close-ups.  Many stereo photos, of flowers or insects for example, are taken at a lens to subject of 30 to 300mm, which requires a lens separation of 2 to 20mm, from the 15 to 1 Rule. This is difficult to achieve with most 3D cameras. Hence the sequential method (described earlier) is generally used, preferably using a slide bar to get the separation and alignment correct.

Alignment of digital images. Pairs of stereo images direct from the camera need to be correctly aligned for comfortable viewing.I use StereoPhoto Maker, from http://www.stereo.jpn.org/eng/stphmkr/.  It is free and very easy to use and the programme can be set to run automatically to align 50 or more images in a few minutes. It is generally best to examine each of the auto aligned images, and maybe tweak the images to get the best effect that you like. 3D videos can be aligned using StereoMovie Maker, from the same website.

Viewing Stereo Images

Prints.  Simple folding paper viewers are available for viewing side-by-side prints of stereoscopic pairs up to 170mm wide, eg Loreo viewer.  Brian May, the Queen guitarist, has designed a simple plastic viewer, the Owl Lite, available from http://shop.londonstereo.com/LITE.html.  For larger prints, prismatic specs are available, which widen your field of view, and can be used for eg A3 size images.

 Using an autostereoscopic viewer.  Some newer digital picture frames incorporate a screen fitted with a special viewer, which ensures that your left eye only sees the left image and the right eye only sees the right image.  No glasses are required to see these images in 3D with these viewers.  Some Android tablets have glasses-free 3D screens using a barrier screen eg the ROKiT IO PRO 3D, Doogie Y6MAX 3D, or the Elephone P8 3D. Unfortunately, 3D kit is often not available for long, as demand is low, but there is always Ebay for picking up a bargain. Glasses-free tablets and mobile phones use a barrier screen to view the image in 3D. This is based on the principle that the eyes see slightly different parts of an image, when viewed through a gap in a barrier. With the correct geometry it can be arranged that the left eye only see strips of the left image and the right eye only sees strips of the right image, which the brain puts together as a 3D image.

Computer screens and TVs.  Prismatic spectacles are the simplest and cheapest viewers available for viewing side-by-side stereo pairs on a computer screen or on a normal TV.  Home make 3D images can be viewed on a 3D TV with appropriate glasses. Many digital stereo cameras have a mini HDMI socket to enable transfer directly from the camera to a 3D TV.

3D Digital Projection is expensive, but is great for viewing images in 3D on a large scale and to large audiences. Most people use twin digital projectors fitted with polarising filters.  The audience will need to wear polarising spectacles, like those used in a cinema. It is possible to use a single digital 3D projector, but the audience will have to wear appropriate active polarising specs, which are rather expensive.

3D Video making.  There are many software packages which enable writing 3D videos for home use. These can be made from 3D still images and/or 3D video clips. These packages include Magix, Sony Vegas, Pro Show Producer etc.

The Stereoscopic Society, founded in 1893, supports 3D photography and photographers in many ways. Meetings are held in London, Coventry and Edinburgh, once a month at each venue, from October to April. Members 3D images and 3D videos are projected and the meetings offer members an opportunity to catch up on the latest developments in 3D. Some 3D equipment is offered for sale to members and there is the opportunity to borrow books from a 3D library. See www.stereoscopicsociety.org.uk for further details. A very detailed account of stereoscopic photography is given in the book http://atbosh.com/books/magical-images-a-handbook-of-stereo-photography/ written by Geoff Ogram, a committee member of the Stereoscopic Society.

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