|
Getting Started/ Help
Why isn't stereoscopic
photography more popular?
Surprisingly, a significant
percentage of the population just can't see 3D.
Where do I start?
Every available method for creating
3D images has some inherent flaws or drawbacks. This is a quick
overview in an attempt to avoid wasted effort and achieve good results.
To begin, you will need two
images of the same subject taken from slightly different horizontal
perspectives. Beginners can start by simply snapping two hand-held images
taken about 3 inches apart horizontally. Make sure that the camera is held at
roughly the same angle for each image and centered at the same point on the
horizon.
Two disposable cameras taped together facing the same
direction with zero parallax can also be used. When the shutters are released
simultaneously, the resulting images will be nearly equivalent to any stereo
camera of the 1950's. This is an easy method with no need for special film
processing or handling. The lenses should be spaced 2-1/4 to 3 inches apart.
The left camera image is viewed with the left eye and the right camera image
with the right eye.
Better results can be achieved
using two quality cameras hard mounted side by side on a bracket. The
shutters are released simultaneously using an electronic or dual cable
release. This configuration tends to be a bit awkward and bulky, but the
results are very consistent and predictable.
The downside of using two cameras is variation in the image exposure and
shutter synchronization.
For still life photography the
best system to use is simply a single camera mounted on a slide mechanism
which moves left to right 2-1/4 to
3 inches. Take one photo at each extreme position.
Slide mechanisms, dual cable releases,
brackets and other stereoscopic hardware are available at the Berezin Stereo
Photography Products link below.
3D Glasses
Checkout http://www.rainbowsymphony.com for
great prices on a variety of different formats of 3D glasses.
Anaglyph Images (red/blue)
Anaglyph images are produced
easily from existing image pairs using a computer. RGB (red-green-blue) color
separations are made of each image. Typically the red information for the
anaglyph comes from the left image only. The green and/or blue information
comes from the right image. The desired separations are merged together to
create the anaglyph. If identical features are aligned in the color
separations, those features will be flush with the image window when viewed
with red/blue(cyan) glasses. If a black and white image pair is used to
create the color separations the output anaglyph will be easy to view and in
a simple traditional format. If a color image pair is used to create the
separations the anaglyph will retain some of the color information and give
the effect of a 3D color image. This may be difficult to view in some cases,
especially if the original images are comprised of large areas of red, green or
blue. Color anaglyphs are best when they are mainly combinations of yellow,
magenta, gray or brown. Anaglyphs can also be created using color filters
with double exposures when a stereo image is photographed. However, the final
picture will usually tend to be confused with remnant images that bleed
through each filter because most films/video are sensitive to spectral ranges
extending beyond visible light. Cold mirrors or IR filters may be required to
correct this.
Color Bleed/Ghosting
Color Bleed will occur in
anaglyph images when the image data intended for one eye is also perceived by
the other. The most common reason for this to happen is from poor filtering
of the separate image colors. It can also occur when the final output images
are created using jpg and other "lossy" formats. These formats use
color substitutions that are rarely true to the original. This may jumble
together the left/right image data. It is highly reccommended to use
"lossless" file types such as gif, tiff, or bmp whenever possible,
especially if Color Bleeding is a problem.
ColorCode 3D Anaglyph
ColorCode 3D refers mainly to a
specific type of amber/blue glasses used to view anaglyph images which are
created in the yellow/blue format. Projected images can be quite stunning,
but printed images tend to be difficult to view especially using incandescent
light which lacks sufficient blue light.
Halfcolor (Truecolor) Anaglyph
Halfcolor is an anaglyph
technique of using one grayscale image and one color image as the stereo pair.
Results can be surprisingly good. To create a halfcolor red/cyan anaglyph,
the left color image is converted to gray then used to create the red color
separation. The right image is used un-altered to create the green and blue
separations. The output image will have muted reds since they have been
averaged with the blues and greens, but the overall image will be easier to
view because luminance from the blues and greens is no longer isolated to the
right image.
JPS Files (jpeg stereo)
JPS files are simply cross-eyed
stereo pairs that have been saved in the jpg image file format. Files created
with the Vrex software may also include file tags which enhance the format,
but are not part of the original standard.
Phantogram Images
Phantograms are anaglyphs designed
to be placed on a horizontal surface then viewed at a 45° angle. If done
properly the 3D image will appear to be resting on or above the surface. When
creating phantograms, placing the source objects on a rectangular grid can be
helpful. A stereo pair of the source objects is photographed at same location
that the phantogram will be viewed from, at 45° from the horizontal. An
anaglyph is created where the three dimensional image appears in front of the
anaglyph surface. The image is stretched to make the grid lines (imaginary or
otherwise) of the anaglyph distort where they appear rectangular (zero
parallax) having no perspective. When the final edited anaglyph image is
placed on the horizontal surface and viewed at 45° the grid lines in the
image will follow the normal perspective. This gives the illusion from the
viewing point that 3 dimensional objects in the anaglyph (phantogram) are
resting on the horizontal surface.
Jigglevision/Wobble Stereo
This is a very interesting method
that can produce 3D effect without the use of glasses simply by flipping back
and forth between the images of a stereoscopic pair. The most common computer
format is the animated GIF file (89a) looping the sequence with a delay of
1/10th second or a bit longer. This will allow 3D perception with
only one eye.
The 30:1 Rule
Unless the intention of the
photographer is to produce a hyper/hypo stereo pair it is generally advised
to use the 30:1 rule. This simply means that the horizontal offset used
in taking the images is 1/30 of the distance to the object.
Trapezoidal Distortion
In general, image pairs should be
photographed with zero parallax angle. This is because the images are
recorded on a flat plane. When the parallax angle of a stereo pair changes
from zero the resultant images will elongate opposite to each other. If the
subject is a box, the images become trapezoids.
Loreo/Argus Camera and Vivtar 3D Cam
The Argus/Loreo and Vivitar 3D Cam stereo cameras are probably the easiest to use for
prints. Using reflectors and lenses the camera creates a parallel stereo-pair
on a single frame of 35mm film. No special processing is required. The prints
can be easily viewed with the magnifying viewer which is supplied. The
drawbacks to the camera are a fixed focus lens, fixed shutter speed and in
the case of the Argus/Loreo the need to use a plastic adapter mounted on the
front of the camera to prevent internal reflections which ruin a photo.
Internal reflections and light leaks have ruined many photos that I have
taken with this brand of camera. The new Loreo MKII camera has been vastly
improved. It has glass mirrors and internal reflections have been reduced.
Loreo also sells a stereo adapter for
35mm SLR cameras called a “Lens in a Cap”. It is basically a complete
lens system that can create a stereo pair on a single 35mm frame. The
adapter has 3 focus settings and 2 f-stops (f22& f11). Images are okay,
but the mirrors in the unit I have are mis-aligned and the exposure for each
image is slightly different.
The Vivitar 3D Cam
camera is described at: http://www.vivitar.com
and available at Berezin Stereo Photography Products below.
Nimslo Camera
The easiest camera to use for 3D slides
is the Nimslo (4 lens) camera with the two center lenses masked. When
processed the images are half-frame 35mm (slightly offset) and the film
processor should be told to mount one image per slide. Half of the slide will
be black. The Nimslo is fixed focus, but has electronic exposure control. The
camera can be used as originally intended (all 4 lenses unmasked) with print
film and can be processed into lenticular prints which are quite novel. The
only drawback is that the lens spacing is not quite adequate and the photos
lack realistic three-dimensional effect.
Negative Scanners
An easy alternate method to use with unusual
film formats is a digital negative film scanner. I use an HP S20 scanner that
can accommodate the odd frame sizes.
NuView Video Adapter
The NuView adapter is quite
impressive and works with many different camcorders. The interlaced video can
be viewed on any TV with the addition of de-interlacing glasses. Since the
camera uses polarizing shutters to control interlacing, the system suffers
severe image flaws from polarized sunlight reflected from surfaces such as
windows and water. The system is expensive and somewhat bulky and is
currently available at http://www.razor3donline.com.
Pulfrich Effect
To experience the Pulfrich
effect, put on your Pulfrich glasses (described below) and
Click here
This is by far the most robust
method available to create 3D films or video. When objects move horizontally
across a background, and they are viewed with a moderately dark filter
covering only one eye, a stereoscopic phenomenon called the Pulfrich Effect
can occur. Depending on the speed and direction of objects and which
eye is covered, objects will appear near or far relative to each other. This
effect is the basis for the method used in many current 3D TV show specials
and videos.
You can create high quality 3D
sequences by doing simple dolly shots with a camera. View the sequence
through dark sunglasses with one lens removed. If the camera is moving right
to left, remove the left lens. The speed that the camera moves is not
critical. There is a minimum speed where the effect disappears and a maximum
speed where images move by so fast that you want to puke. The effect is based
on optical signal delay and ratios of shadow-like effects of the near and far
objects which are merged in the brain. Regardless of what speed you travel
the ratios are the same. Objects moving across the view-screen at the speed of
the camera (in the opposite direction to travel) will appear flush with the
screen. Objects moving the least will appear to be at the horizon. You can
capture a sequence off to the side as you walk and get 3D or from a bicycle
or car. Usually the effect will kick in if you are only moving a couple of
miles per hour. Less if you are close to the subject.
Pulfrich videos can also be
viewed with LCD glasses that are synchronized to view the interlaced images
in the proper field sequence order. Pulfrich videos are so versatile they can
even be viewed with no glasses at all as a 2D presentation.
You may need to experiment with
different strengths of filters. If the density is too dark or too light the
effect will tend to diminish. Also, the filter should be as neutral color as
possible.
Realist Format Cameras
High quality stereoscopic slides
can be created with antique (1950's) stereo Realist cameras. Kodak, the David
White Company and others produced cameras using an odd format which
requires special processing to mount the 24mm x 24mm images. Do-it
yourselfers can find supplies for this at the Reel 3D Enterprises link below.
Lab processing is also available, but hard to find.
Reel 3D Enterprises
To find all of your stereoscopic
needs go to: http://www.stereoscopy.com/reel3d/
or
Berezin Stereo Photograpy Products
at: http://www.berezin.com
Return to Index
Return to Main
|