On 17/8/04, graywolf, discombobulated, offered: >It is just a beamslitter (semi-transparent mirror) like in a rangefinder, >Cotty. >Canon has used them in a couple of cameras over the years. The advantage >is it >does away with the moving mirror, the disadvantage is the viewfinder is >about a >stop darker. I believe you also lose about a stop of exposure.
Thanks Tom (and Sylwek). Got it. I was stupidly thinking of pellicle mirrors as used in the motion picture industry. High speed motion picture film cameras use pellicle-mirror type prisms that rotate so the film can run continuously, without having every frame having to stop dead 24 or 25 times a second to be exposed. If any of you have ever seen, or ever get the chance to see a Steenbeck editing table, have a look at how the film is projected onto the monitor - it uses a non-stop prism system that the film passes by, the prism rotating - rather like jumping on a merry-go- round for half a turn and then jumping off again. Picture of Steenbeck: <http://www.terryjonespostproductions.co.uk/about.htm> Closeup of film transport mechanism: <http://www.kreekfilmservice.com/productssimple.html> the prism is round with lots of sides, located just to the left and just above dead centre of the pic, where the bright bit of light is emanating - the two things either side move to allow the film to be placed onto the sprockets, then snap shut again. The complete prism is hidden beneath the dark housing. <enough film editing lore> Thanks guys. Cheers, Cotty ___/\__ || (O) | People, Places, Pastiche ||=====| www.macads.co.uk/snaps _____________________________
