From: 739chan1@gw.wmich.edu
Newsgroups: rec.photo
Subject: Re: How to make a good ghost illusion?
Date: 1 Oct 92 18:00:39 EST
Summary:   :*  Creating Ghosts!!
Keywords: Ghost, multiple exposure
Distribution: world
Organization: Western Michigan University

In article <1992Sep24.110944.25666@sequent.com>, blue@sequent.com (Gil Delavous) writes:
> Hi,
> 
> I'd like to take a funny picture of ghosts!!!  This is how I would
> proceed:
> 
> 1/ Take a first picture of a couple of guys in front of any
> background.
> 
> 2/ On the same picture, take another shot of the backgound whithout
> the guys.
> 
> That way, the guys should be partially covered by the background and
> looks like ghosts.
> 
> I'd take that picture during the night and using a flash. Since
> I never tried this kind of picture, do you have an idea if that
> may work?  Is one extra shot enough?  Did anybody try a picture like
> this? How did you proceed? What was the result?> 

    I did try something like that a few months ago. Like one of the guys who
replied to this, my intention was different; I wanted to get a shot of my
friends standing with their "twins". So we went to the middle of a golf course
at about midnight (we couldn't find any other dark place). My camera does not
have a facility for multiple exposures. So I had to use the B setting and make
long exposures.(Hence the need for a dark place). 

Here's how we did it:

1) My friends get into position.
2) I open the shutter, using a locking cable release. (Shutter speed,
   B setting).
3) I manually fire a flash.
4) My friends walk to a new position.
5) I fire the flash again.
6) I close the shutter.

   Since it was a dark place, the film only recorded the images when I fired
the flash. My friends' walking around were not recorded. The pictures turned
out beautifully, except for a few, where the people looked like ghosts. This
was probably due to me firing the flash before it was fully charged. My
friends, however, were absolutely delighted at the shots.

   If I learned anything from this experiment, it was how to produce ghosts.
Firing a semi-charged flash is equivalent to underexposing a subject. In fact
some books say you SHOULD underexpose subjects in multiple exposures. This is
because the cumulation of exposures will result in overexposure for a single
frame. I calculated the exposure for my shots based on the flash index. I under
exposed by 1 stop. The properly exposed shots had "twins" (solid people) , 
the underexposed ones (due to the semi-charged flash) had ghosts.

   So you might want to try this in normal lighting:
1) Find a suitable background.
2) Set up your camera with a tripod.
3) Take an exposure reading.
4) Take the picture, one stop underexposed.
5) Ask you subject to step in.
6) Activate your multiple-exposure facility.
7) Take the picture again, two stops underexposed.

  Of course this is a very rough guide on how to do it. You should experiment
with different amounts of underexposure as well as backgrounds. But the general
rule is, the more underexposed your shot, the fainter the "ghost" will be.

Good luck, and tell me how things turn out.

Boo,
__________________________________________________________________________
Chan Lee Meng          \  "Let us endeavour to live so that when we die,
739chan1@gw.wmich.edu    \   even the undertaker will be sorry."
X92chan3@gw.wmich.edu      \   - Mark Twain.
Western Michigan University. \