Loadstar 128 #10/q10.d81/t.screen_photo

Text File | 1990-01-01 | 7.5 KB | 141 lines

                          PHOTOGRAPHING YOUR MONITOR

                              by Jeffrey L. Jones


     Have you ever noticed that TV images look funny in the background of
snapshots?  Photographing the television or the computer monitor has long
been a problem for still photographers as well as motion picture
photographers.  But the problem is easy to overcome.  All you have to do is
remember a couple of simple techniques.

     If you have a 35-millimeter camera, or a camera that allows control of
shutter speed, shooting photos of your monitor can be quite easy, especially
if you use a time-tested technique called "bracketing".  More on bracketing
later.  If you own a smaller, cheaper "sureshot-type" camera, there's still
help for you.  Read on.

                         OVERCOMING THE STROBE EFFECT

     The number one problem with shooting pictures of your monitor is
synchronizing the shutter with the screen display.  In other words, exposing
the film while the picture is actually on the screen.  This may sound weird
but it's true.  You perceive your TV as showing a constant picture when in
actuality, the monitor is strobing (flashing) a rapid series of pictures, 60
times per second.  This strobe effect can be seen if you spread your fingers
and rapidly wave your hand in front of your picture tube.  If the light were
constant, you'd only see a blur of your hand, but since your monitor is
flashing, you'll see individual sharp images of your hand as it moves back
and forth.

     Synchronizing with the strobing screen is simple.  You simply lower
your shutter speed below 1/60th second.  Since your screen flashes sixty
times per second, your film is exposed to at least one whole frame of the
image.  If the image is a still image, there shouldn't be a problem with
blurs.  If the image is moving, you may notice a double image, but not a
blurred one.  So if the image you're photographing is animated, you may want
to stop it.

                             SHOOTING THE PICTURE

     You really should have a tripod when you shoot below 1/60th of a
second.  Below that speed, your hands are just too unsteady.  Little things
like your heartbeat jarring your body will muff up pictures at these speeds.
You should also use a cable to snap the picture, since your finger can cause
the camera to shake when you push the button.  If you don't have a cable,
you can substitute a self timer.  Most cameras have 10-15 second timers that
allow you to get into the picture.  That delay also allows vibrations to die
down.

     If you don't own a tripod, you can try sitting in a comfortable chair
that's positioned squarely in front of your monitor.  When you press the
button, squeeze it slowly and don't breathe.  Don't force the button.  Just
ease it down.  Your camera's lens should be dead center on the screen,
especially if you're using a short lens.  You're shooting a flat image.  If
you're off center, you can tell.  Your brain tends to correct distortion in
the real world, but it doesn't correct distortion in small pictures.
Perspective distortion is less of a worry with longer lenses, 100-200mm
(though longer lenses usually can't focus close enough to close in on a
13-inch picture).

     If there is any type of glare, turn off all lights and close the
curtains.  If you can't seem to get rid of glares or reflections of
yourself, you might want to invest in a polarizing filter.

     Adjust the brightness and contrast on your monitor so that it looks
good to you.  Get close.  Try to block out the frame of the TV (unless you
want it there).  You may have to sacrifice a bit of your image.  Focus.  Set
your aperture to 4 and shoot.

     Here's where BRACKETING comes in.  You'll have to invest in five or so
pictures for bracketing.  Bracketing simply means shooting the same picture
a number of times at various exposures in order to assure that ONE of those
photos was at proper exposure.

     So you would shoot your first picture at an aperture of 4, then 5.6,
then 8 then 11 then 16.  If your camera has automatic exposure mode, you may
want to trust it for a shot or two, but make sure that only the APERTURE is
on automatic, not the shutter.  Sometimes automatic is better because in
cameras like mine the aperture is "stepless", allowing thousands of possible
apertures instead of six.  The average camera's exposure meter is
surprisingly accurate.  But there are pitfalls to auto exposure.  If the
meter is center-weighted and the center of the image on the CRT is black,
the camera may try to overexpose the picture.  If your meter takes an
average of a large portion of the viewing area, you're safer.  Check your
manual.

     The instructions above were for ASA 100 film (ASA is what veteran
photographers call ISO).  The 16 exposure will probably be way too dark, but
then again, I don't know what type of film you'll be using or how bright
your monitor is.  Basically, 16 with 400 speed film is the same as 8 on 100
speed film.  400 speed film is two stops faster and ten times grainier.
Faster is NOT better.  I'd suggest using a slower film like 100 film.  It's
cheaper and less grainy, and you only lose two stops.

     If your camera doesn't offer aperture and shutter speed control, there
are ways to overcome the limitation.  If your camera has a pop-up flash,
turn the flash on.  Of course you don't want to use the flash on your screen
-- that would cause a supreme glare.  But turning on the flash will usually
set your camera below 1/60th sec exposure unless it has a leaf shutter.  Now
all you have to do is block that flash.  Wrapping it in aluminum foil should
do the trick.  Aluminum foil is completely opaque.  You might find that
black electrical tape works, but it may not be as opaque as you think when
20-100 joules of energy is trying to force its way through.

     If your camera doesn't offer control over aperture size (f-stops), you
can bracket with the CRT's brightness control.  Select a range  of
brightnesses and shoot them.

     Another note on film: If you're shooting reversal film (slides), you'll
need to bracket because reversal films are less forgiving than negative
films.  What you shoot is what you get.  If your lens allows half stops, use
them.  You usually get about 1.5 stops latitude with reversal film.  Beyond
1.5 stops underexposure, slides start to look REALLY dark.  Overexposed
slides look very pale.  The upside is slides ARE more colorful and
contrasty.

     Color print film (negative film) offers more latitude and compounds
that latitude with the fine-tuning that a lab can offer when it prints the
negatives.  With color print film, your photos are usually color-corrected
and exposure-corrected before you see them, so a photo can be grossly under
or over exposed when you shot it yet it looks fine to you on paper.  For
picture perfect slides, you may want to shoot on color print film and then
have the negative made into a slide at the lab.  This can cost anywhere from
forty cents to a buck fifty.  The lab (if it's a good one) will correct your
image when they create the slide.  Note: your negative will be returned.

     Finally, you should check with your local labs and find out which ones
number your prints.  That way you can be sure you're matching up the proper
negative with the picture you like.  Believe me, it can get hairy trying to
distinguish one negative from another, especially when each is of the same
subject.

     That's about all there is to it.  Experiment and bracket, and you can't
miss.

JLJ

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