Question about filming movies in 3-D

Discussion in 'Archived Threads 2001-2004' started by Tom-G, Feb 16, 2002.

  1. Tom-G

    Tom-G Screenwriter

    Joined:
    Mar 31, 2000
    Messages:
    1,638
    Likes Received:
    2
    Location:
    Pittsburgh, PA
    Real Name:
    Tom G
    First off, how are movies filmed in 3-D? Secondly, was this just a gimmick that faded in and out over the years? I can't think of the last film in 3-D. Jaws 3 maybe? Or was it one of the Nightmare on Elm Street movies?
     
  2. Hendrik

    Hendrik Supporting Actor

    Joined:
    Oct 23, 1998
    Messages:
    595
    Likes Received:
    0
    ...have a look here:
    http://www.mindspring.com/~dmerriman/Imaxwrk.htm
    ...in the history of the cinema, 3D movies came (MGM's anaglyph shorts from the late 1930s) and went and came again (early 1950s, see below) and went again and came again (1970s and 80s - remember Jaws 3D and Fiday The 13th Part III and Andy Warhol's Flesh For Frankenstein) and went again... and now they're back - on the IMAX screen...
    ...did you know that Alfred Hitchcock's Dial M For Murder was filmed in 3D?...
    ...so was at least one MGM musical - George Sidney's Kiss Me Kate...
    ...John Wayne appeared in 3D, too: John Farrow's Hondo...
    ...so did Vincent Price: House Of Wax - whose director, André de Toth, only had one eye so he could not actually see the 3D effect...
    ...ahh... memories of long ago...
    . . . [​IMG] . . .
     
  3. Leo Kerr

    Leo Kerr Screenwriter

    Joined:
    May 10, 1999
    Messages:
    1,698
    Likes Received:
    0
    3D-IMAX is something of a special version of how it all works.
    "Conventional" 3D films are not near so fancy. First, they may or may not be photographed with two cameras. An alternative mode is to use a 3-D adaptor which screws onto the front of the lens, and divides the film frame into two seperate sub-frames. This is much easier to work with, because then you aren't always fighting to keep both pieces of film in sync all the way through the editing and the rest of the post process.
    This also solves another important issue - especially important in the world of color.
    If you are working in color, and are using two seperate pieces of film, there are a tremendous number of areas that you can generate false 'differences' that make the 3-D process work. If the film stocks are slightly different. If the processing chemistry changes ever so slightly. If the optical printer suffers a voltage variation to change the brightness and color temperature of the lamp - all for one eye only.
    On final distribution, however, most send out only one 'film' with split images. The projectionist then mounts the appropriate adapter onto the projector, the ticket clerk hands out the glasses, and poof! 3-D!
    There are... numerous variations of how to shoot 3-D. Some mount the seperated frames side-by-side. Others top and bottom. Within that pair of variations, comes the pair of variations of how they are mirrored or not. Anamorphic or not?
    The Russians came up with their own variation that did not require special glasses to watch. Instead, it needed a special screen, shaped with vertical ridges. The images were projected from a steeper off-set, so one image would only illuminate one side of the ridges, whilst the other lit the opposite sides. Then, if the viewer sat in the area for where this miracle worked, Wow! 3-D without the glasses!
    I wonder, as an aside, how well this worked, and how limited the viewing area was. I'd sure like to see it work, rather than just a drawing of how it should have worked.
    One of the great liabilities of 3-D - particularly polarized 3-D - is light.
    A good polarizer eats 1 stop of light, that is, 50%. So, let us consider an IMAX-3D.
    The dual-projector has two 15kW Xenon arc lamps. The light passes through the film, which then converts anywhere from 10%-99% of the light to heat. Sorry, that's how film works. On average, let us imagine that we've just cut 50% of the light.
    The light then passes through the lens, and then hits the primary polarizer. This immediatly dissipates another 50% of the light into heat. We are now down to the effect of having an IMAX projector with a 7.5kW lamp (I'm not counting the film here - that would be there anyway.)
    The projection expands out and hits the screen. Reflecting back, it meets first with the secondary polarizers - the ones in the glasses. Now, in theory, these don't filter out that much light - after all, the light has been match-polarized to the glasses, right? Everything should just pass through, right?
    Wrong! Roughly 50% of the light is now filtered out. Again.
    The effect is that the projector has a useful light of 3750 watts/eye. Assuming, of course, that the screen has a perfect reflection (which it doesn't.)
    But remember as well that this 3750 equilvalent - nearly twice that of a conventional movie house - is being spread over a screen, say, 8 times the size. Thus, if my Sunday morning math engine is working, we have a useful illimination of ¼ that of the conventional movie-house.
    Scary, isn't it?
    Now do the same - in a movie house!
    Leo Kerr
    Lkerr1@alumni.umbc.edu
     
  4. Hendrik

    Hendrik Supporting Actor

    Joined:
    Oct 23, 1998
    Messages:
    595
    Likes Received:
    0
  5. Tom-G

    Tom-G Screenwriter

    Joined:
    Mar 31, 2000
    Messages:
    1,638
    Likes Received:
    2
    Location:
    Pittsburgh, PA
    Real Name:
    Tom G
    Gentleman, I learned a lot about 3-D from your posts and links. Thank you for taking the time to share. I remember seeing The House of Wax during the Halloween season when I was about 10 years old (I'm 28 and too young to have been around for the original release). I enjoyed the film immensely, but that was when I was a child. I'd like to watch it again at some point, hopefully in 3-D.

    Leo, I suppose the Russian innovations for 3-D viewing didn't quite pan out the way they hoped? Although it is somewhat of a gimmick, it seems like that type of screen and way of watching movies is something that would have been attempted in this country as well.

    Interesting stuff. I'd like to watch a film using the Russian variation.
     

Share This Page