On 6 September 2011 09:44, David Savage <[email protected]> wrote: > On 6 September 2011 04:47, William Robb <[email protected]> wrote: >> On 05/09/2011 12:51 PM, Larry Colen wrote: >>> >>> I wonder if this would work, and if so would there be a market for it... >>> >>> To make a background for photos, take a projector that has video inputs >>> and shine it on the background. It wouldn't be bright enough to not get >>> washed out by strobes, so replace the halogen bulb with a strobe. You'd >>> need a modeling bulb for it, but it wouldn't need to be as bright as the >>> regular bulb used in those projectors. >>> >>> It would also be handy as flash that had it's own built in gels, of any >>> color you wanted, as well as it's own gobo (up to the contrast ratio of the >>> LCD). >>> >>> I wonder what it would cost to make one, and how much of a market there >>> would be for them. >> >> It's easier to just do a green screen. > > ^ Wot he sed. >
My vote is for green screen too. In the olden days, when film was king, studios used complicated rigs called "front projection units" to photograph moving subjects. The camera was mounted above a projector, and the optical axis of both was aligned along the same axis, having been merged by a semi-silvered mirror. Behind the subject was a special screen which had very high reflectance but a very small viewing angle. It only needed to be seen by the camera lens after all. The whole setup was fixed, no movement of the camera was allowed so you had to reposition the subject to recompose. The screen had to be shaded from the studio lights, as Bruce already observed, but the comparatively low reflectance of everyday objects compared to the high reflectance screen meant that the projected image falling upon the photographic subjects wasn't discernible. Rear projection was a viable alternative but required very much more space in the studio, and the screen texture could be troublesome. Another method required a removable film holder or magazine and was only useable for still-life subjects. "In-camera masking" was a complicated workaround requiring two exposures, two lighting setups (one for the subject and one to create a silhouette of the subject), a background change from black velvet to bright white, and the placement of a transparency directly in front of the film, to be contact printed as the background. The subject itself would create the mask that prevented double exposure. Getting the film holder or magazine onto the camera in perfect register every time, without moving anything at all, was a challenge. But the results blew away front or rear projection. Sometimes working with film was a real pain-in-the-arse. regards, Anthony "Of what use is lens and light to those who lack in mind and sight" (Anon) -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
