On Mon, 19 Nov 2001, Gareth malham wrote: > has anyone got any diagrams of a larscan camera, i have seen the info at > panoramic.net but it is somewhat vague and i am having trouble grasping how > i got about converting a folding body, i'm sure a simple drawing would set > me right. I have been trying to obtain a copy of michel duraiez's book but > to no avail.
Last I checked Mr. Dusariez is a subscriber to this list. He might be able to help with your book search. > I have built a camera based loosely based on the idea have a > look - malcam.fucx.co.uk However it was full of faults and is very > haphazard. Didn't have any luck with this URL. In any case, I'd suggest a good source of on-line material would be some of the papers made available by Prof. Andrew Davidhazy at RIT. One way to find these is to go to <http://rmp.opusis.com/htdig/search.html> and search on "davidhazy panoramic". He provides a fair amount of technical information in his writings. Some selected articles are: http://www.rit.edu/~andpph/text-strip-basics.html http://www.rit.edu/~andpph/text-strip-bracket.html http://www.rit.edu/~andpph/text-strip-instant.html As for the Larscan camera, it is primarily a strip camera. The camera body rotates while the film transits past a slit inside the camera. What makes the Larscan unique is that the tripod mount is a bearing through the base of the camera with a wheel that contacts the film. You only need to motorize the film take up spool this way, and the film effectively pulls the camera around the tripod mount. Let's try an ASCII diagram: Side View: | | | | <-------------------Film plane | | |------------| |( ) wheel ( ) <------ Rubber O-ring | |------------| | | | | <------- Fixed Shaft | | =========[]| |[]========== <-- Camera Body | | |------------| | __ | | < > | <----- Tripod mount | > < | |____< >____| The tripod mount, shaft, wheel and O-ring are all fixed. The film contacts the O-ring, and the camera is the only part free to move. As such, when the film translates through the camera it pulls the camera body around the wheel. Hope this helps a bit. > My plan is to build a larscan that takes 24hrs to rotate using two > polarizing filters controlled by a microprocessor and a small motor to > control exposure. Any thoughts on this idea? Exposure in a slit camera is controlled by rotational speed, slit size, and lens aperture. A 24 hour rotation is really slow, necessitating a very small slit size, really small aperture, and/or as it sounds modulating the light using crossed polarizers. Not too sure what you are trying to do so don't really know how to approach the design. One problem with panoramic cameras is keeping the exposure consistent across the strip of film. I'd assume that this would be a BIG problem with a 24 hour exposure unless you are in an artificial environment where you can control the illumination. Also, my gut feeling, for what it is worth, is that you may need better control of the camera rotation and film translation speeds than what you can probably get with the Larscan design. If you are already talking about microprocessor control it would probably make sense to consider using stepper motor control of both the camera rotation and film translation. What do you have in mind for the controlling microprocessor? A laptop, an embedded controller, or maybe a basic stamp <http://www.parallaxinc.com/>? - Wayde ([EMAIL PROTECTED]) _______________________________________________ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
