double exposure in-camera SFX

[Grainy]

Hi there -
I want to do that old trick where you create "twins" on camera by simply blacking off half the image, shooting a person in the non-blacked off section, rewinding the film, then blacking off the opposite side and having the same person be photographed again, in the new position, resulting in two images of the same person.
My question is: what's the best way to actually DO this? How does one black off a perfect halfway mark, then make another one exactly opposite so there isn't some hair-line mark indicating that two exposures have been made?
Does this make sense? I'm not very crafty with my hands, and I can totally imagine using a ruler or something to measure off two hunks of cardboard and having them end up being a tad off and botching the whole process... help!
G

 

[DaPetes]

Wish i could help u, but i was wondering this same thign as well, so im glad you posted. But these boards are moving slow as hell, so gl on a response lol,

 

[Filmosity]

That's an old film technique called matte. I assume you're using film, and that you have a decent camera. What you actually need is a mattebox into which you set a matte frame. The specifics of the technique are kind of foreign to me, as I'm a video guy, and I usually do that effect in post production.

 

[David Mullen ASC]

You'd have to set-up some sort of rigidly locked frame relative to the camera so that you could mark the two halves of the mattes on the frame and know exactly where one begins and the other ends, with no change in position relative to the camera. Now if this is a locked-off shot, you could lock-off the camera, sandbag it, put a frame in front of the lens, lock that down to the floor, but ideally you'd have a long mattebox where you can slide mattes in the front, unless you needed a sharper matte line.

 

[Grainy]

You'd have to set-up some sort of rigidly locked frame relative to the camera so that you could mark the two halves of the mattes on the frame and know exactly where one begins and the other ends, with no change in position relative to the camera.

that makes sense -- I guess what I'm wondering is whether there's a set way to make these markings. For example, would you use a clear glass slide with a black mask over one end, then flip it over? It seems like this was done so often in the old days that there'd be a "best practice" for it?
thanks
G

 

[David Mullen ASC]

If it's a simple vertical split, you don't need glass -- you just need an outer frame that you can mark up. You have a black card for the left half, let's say, and mark on the outer frame where the matte ends, and then you flip it and put the black card on the right side so that it ends at the same marks on the outer frame.

Glass is more useful for painting a complex matte around an area, let's say, an uneven "S" shape. But then you'd have to figure out how to paint a second plane of glass with the opposite "S" shape that lines-up, probably by overlaying the glass and tracing the edge onto the new glass.

The softer (more out-of-focus) the matte-edge, the less critical the alignment because there is some fuzzy overlap in the composite. The harder the matte edge, the more likelihood of seeing a matte line.

 

[directedition]

In terms of composition, it is best to have the slit line up with something like where two walls meet in the corner of the room or such, so the imperfections in the lineup appear to be a part of the scene. Though I have known people who live and breathe the Bolex who can piece together a matte perfectly all Uelsmann-like if they take their time.

 

[Grainy]

The softer (more out-of-focus) the matte-edge, the less critical the alignment because there is some fuzzy overlap in the composite. The harder the matte edge, the more likelihood of seeing a matte line.

Oh -- then is it correct that:
1 - the black card solution I build in a matte box would likely be out of focus (soft/fuzzy) unless the subject was macro-close.
2 - in terms of the space between the left/right black cards, if it wasn't 100% laser perfect, it'd be better to err on the side of there being a tiny gap, rather than the cards "overlapping" a bit between first and second pass, correct? Because if they overlap, it'd produce a black line?

 

[Grainy]

Though I have known people who live and breathe the Bolex who can piece together a matte perfectly all Uelsmann-like if they take their time.

If they'd be willing to share their setups, I'd LOVE to see them.
Never heard of Uelsmann, just looked him up -- he's all in-camera, then?
I read something about Buster Keaton having his personal engineer set up a device with precision sliders so he could rephotograph 8 different Busters seamlessly in one of his early films....

 

[directedition]

Well, Uelsman did his work in the darkroom, still very skilled. I don't have samples of their work with me, but I'll ask if they have quicktime transfers of their work.