Stereo camera
A stereo camera is a special camera for taking stereoscopic photographs ( 3D photography , 3D film ).
Stereo cameras usually have two lenses attached next to one another and, when triggered, enable the two stereoscopic half -images required for 3D images to be recorded simultaneously . The exposure control and focus adjustment of both lenses are coupled.
The lenses, whose shutter is released synchronously, produce two adjacent half images on the film, which combine to form a closed spatial impression when viewed in the stereoscope.
In order to ensure true-to-space reproduction, the two lenses are usually 60–70 mm apart (called the base ), which corresponds to the average eye relief for humans, but varying it produces different effects.
Special versions of the stereo cameras (among others from the Nimslo company ) have four lenses and are used to produce lenticular images .
Two conventional cameras of the same type can be combined with a mounting rail to form a stereo camera after they have been adjusted exactly vertically. Both cameras must be released at the same time, otherwise the spatial perception is disturbed with moving subjects (or moving cameras). Digital SLR cameras that support remote release with a Lanc-1 interface can be synchronously coupled . Older Nikon Coolpix cameras allow this via the serial interface of the USB connection via switch and Palm software.
Cameras with only one lens can be used as stereo cameras with an attachment that enables the simultaneous recording of two fields in portrait format. Appropriate viewing devices are available for such recordings.
When photographing still lifes , one camera is sufficient if the two pictures are taken one after the other with a small offset to the side. Here, too, attention must be paid to an exactly vertical alignment.
Paper prints of stereoscopic images can be viewed by one person at a time using a stereoscope . For several people there is the so-called spatial projection .
In 1894, Jules Richard constructed the first truly portable stereo camera, the "Richard Vérascope". In the 1920s, several devices that were affordable for amateur photographers came onto the market.
Geodetic stereo cameras
With the advent of photogrammetry (terrain mapping using measurement images ), geodetic stereo cameras were also constructed around the turn of the century, which were in use until the 1970s. Two identical cameras aligned in parallel were mounted on a 100 cm long base . B. high building facades , difficult to access terrain or quarries were measured. Also Fototheodolite were used with additional devices for similar purposes.
In isolated cases, stereo cameras with a 1–2 meter base have also been used in balloon photogrammetry , but good spatial resolution is only given up to an altitude of a few tens of meters.
The high resolution stereo camera for exploring the planet Mars should also be mentioned here . It was developed by German institutes for the Mars Express space probe (2003), but it is not a stereo camera in the strict sense. Instead of recording the Martian surface from different angles at the same time (which is technically not feasible), it overlays strips of terrain photographed one after the other , which are recorded diagonally ahead and back in the direction of flight.
Swell:
- Hans Löschner (1930): Introduction to Earth Image Measurement , Verlag Deuticke, Leipzig and Vienna
- DLR (2004): High Resolution Stereo Camera (HRSC)
