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The following is taken from an e-mail reply to a client
who asked about "how to take good laser photos". Others may have
different techniques or views; if so, please write
to us and we'll try to include your suggestions.
I have had good results with the Kodak DC260 series (now
the DC290). This is a megapixel digital camera with the ability to manually
control the shutter. The DC260 series can take time exposures up to 16
seconds(!). As explained below in the film camera section, it is important
to be able to take long time exposures. Around 1 second is minimum --
anything faster (e.g., 1/2 second, 1/4 second) might not be flexible enough for all the types of laser
photos you want to take.
The DC260 is especially nice because you can pop
out the Smart Media card ("film"), put it in a PCMCIA adapter,
plug it into a laptop, and see the photos within a minute after taking them.
If the photos are bad, you can do it again right away -- no waiting for the photo
developing.
There are certainly other digital cameras
which can take good laser photographs. For example, the Nikon
CoolPix 990 series also has long shutter speeds and plenty of manual
control.
For film cameras, I recommend Fuji Velvia slide film.
It is about ASA 50 speed, so you will have to do time exposures. Velvia has
very saturated color, so it is especially good for laser. You should use
slides almost all of the time since they capture the light more accurately.
With film, first the negative is developed, then the print is made; in both
areas adjustments can be made which are fine for "normal" photos
but which ruin laser photos. Of course, once you get good slides then you
can make duplicate prints out of them.
I mostly shoot graphics so the
tips below are for images on a wall or screen.
Your camera should be a
single-lens reflex so that you can see exactly what the lens sees. If
you are shooting anything where distortion could be a problem (circles,
squares) then put up a grid pattern, sight through the lens, and use a
Universal Geometric Corrector or similar device to get the grid square in
the lens. Do not worry about what it looks like on the wall or screen. Just
get the grid OK in the lens. I have done this with raster pictures (many
horizontal lines) and it is essential if you want the final photo to come
out flat and square (not keystoned).
For good results, have the
laser fairly close to the wall or screen. This makes the lines smaller
and thus sharper. Use manual focus; focus with the lights on using a target
taped to the wall or screen. The aperture should be stopped down as you want
sharp focus; such as F16. Don't change the aperture from now on. Change only
the shutter speed.
When I have a new subject, or
have been away from the camera for a while, I take about 5-10 shots of
each image. I start with a quick shutter, 1/16 second, and go up to a
manual time exposure of 16 or 32 seconds. Here's a good tip: After a while
it does not matter how long you open the shutter -- a longer exposure won't
make a significant difference (technically known as reciprocity
failure). So just double the shutter speed each time. Example: 1/16,
1/8/, 1/4/, 1/2, 1, 2, 4, 8, 16, 32 seconds. To avoid wasting film, use
every other exposure time: 1/8, 1/2, 2, 8, 32. For the longer exposures you
can just count off the seconds -- you do not have to be exact.
Of course, the shutter speeds
have an effect when they are fast because fast exposures may pick up only
part of the laser image's refresh. For example, if your scanners are
projecting 8 refreshes per second, and you use an exposure of 1/16 second,
you'll see only half of your graphic!
And it is not enough merely to
catch a single scan. For example, if you catch one-and-a-half scans you
still will see a noticeable brightness difference between the part of the
image which was scanned only once, and the part scanned twice. This is why long exposures
are a must -- you are guaranteed to catch many, many scans.
Be sure to write down the
F-stop for the roll of film, and the exposure for each shot. Also, be
sure that the first 1-2 photos you take AND the last 1-2 photos are with
room lights on. All you care about is to get some bright frames at the
start and end of the roll, so the film processor knows where to cut the
frames! Otherwise, they have an all-black roll of film punctuated with
colored lines. They have no way to tell how to center the colored lines.
I get the film processed the
same day so that I can leave the equipment up and so all the variables
are fresh in my mind. Then I can make any adjustments to the color balance
(using the laser software color controls), UGC, or shutter speeds. It
usually takes me two rolls for a "perfect" shot.
Work with a good lab that
caters to professionals. Tell them what you are doing so they won't
think there's something wrong with the film.
When the slides come back, I write
the F-stop and shutter speed on the slides immediately. You will always
lose the bracketing sheet, so write the data on the slide. You even may want
to write other info such as the film type (e.g., Velvia) or the laser
equipment.
For beams they should emerge from
behind a hole in a cloth or photographic background paper. This is so you
don't see the projector or objects behind the projector. I don't do beams as
often so I can't give you as many specific tips, except "bracket,
bracket, bracket"!
The final topic I want to discuss is electronic creation
or editing of laser graphics.
If you use a digital camera, or
scan in your slides, then you have the opportunity to fix up your photos or
be more creative. Of course, you can adjust the contrast, brightness,
saturation and other elements. But you can do much more.
Two scan heads from one
For example, if you are shooting
a two-scan head beam show, just shoot one scan head, then in a program like
Photoshop, flip the image and blend the two. Using the right blending mode,
you will get a perfectly symmetrical image which looks realistic
(double-bright where the beams overlap). You can see this technique used in
one or two of the beam photos on the webpage at Pangolin.com where you can
download "Windows wallpaper" photos.
Synthetic photos
One of the techniques I have developed is making "photographs" which really started out as drawings.
In Lasershow Designer I might do a screen capture of the LD Drawing Window
(enlarged to maximum size), with no grid lines, dot points, axis lines or
any other background -- just the laser lines. This screen capture is then taken
into Adobe Photoshop. I crop to get only the laser lines, and then add various
effects such as blur and noise. These help simulate what a laser photograph
looks like. Sometimes I will take two versions -- one sharper and brighter,
the other blurred and dimmer and superimpose them to make the
"glow" that can surround laser graphics.
I feel that if this technique is
used appropriately, it is perfectly valid for showing clients or others what the
laser images look like. The test is whether the Photoshop-created synthetic
photos look essentially the same as the real laser-projected images. I feel
they do.
You can see this effect very well
if you get our 4-color brochure with a hand and mouse making a laser spiral
on the cover. There are two versions of the brochure, one in English and one
in German. On one cover, I used the Photoshop synthetic-photo technique. On the other cover,
I shot a photo with a digital camera. Now remember, these photos are nearly
8.5 inches square at 1200 dpi, so you see any flaws! Yet most people would
call the two images essentially equivalent.
There are other examples at our
website of laser "images" which are not true photos but
Photoshop-created synthetic photos. Two notable exceptions are the many scanner
test photos, and the cheerleader photos.
The scanner test photos were taken using a digital camera since obviously the
actual image on the wall is important to evaluating the scanners. The
cheerleader photos were also taken using a digital camera. This was
because for "school spirit" it was important that the
cheerleaders were actually in the laser beams.
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