Slide Projection Systems

General Information

1. All of the auxiliary slide projection systems (not counting special effects) use Kodak carousel Ektagraphic III-E slide projectors.
2. Many of the 21 auxiliary slide projectors are located in the Projection Booth. Most projectors are mounted in Chief projection racks to facilitate stacking, stability, and alignment control.
3. One additional projector is located in the Planetarium workroom to facilitate slide sorting.
4. DO NOT MOVE ANY PROJECTOR! Projectors have been carefully and tediously aligned. If moved, to realign them may easily require a full day's work (or more) by two people.
5. Projectors are named after the location of the projection field, rather than the location of the projector. For example, the right panorama is located on the left side of the Projection Booth. It is called "right" because it projects straight across the dome onto the right side of the dome, as viewed by an east-facing audience. In other words, the viewer's frame of reference is privileged, not ours!
6. Panorama and Informational projectors (see below) are double-stacked in Chief racks to provide "dissolve-pairs," that is, the ability to dissolve between identically-aligned images. The top projector of any dissolve-pair is referred to as A, and the bottom member of any dissolve-pair is B.
7. Slide projectors are connected to Castor control units to facilitate automation. Four Castors are controlled by one Gemini unit, which relays the signals passed to it from the Hercules computer located at the console. For automation purposes, each Gemini is assigned a "unit" number, and each Castor plugged into a Gemini is assigned a "slot" number (increasing from 1 to 4 as the plugs on the Gemini's rear panel move outward).
8. Every projector should have its switch in the FAN position, rather than set to OFF, HI, or LOW.
9. Slide trays hold 80 Wess-mounted slides. For convenience in checking projector alignment, most carousel trays have a horizontal grid slide in slot #80, and a vertical grid slide in slot #79.
10. Every carousel tray has a contents list on the computer, which should be updated any time changes are made. Slides for several shows can be kept in many trays at the same time, but do not rearrange any slides casually. If any slides are rearranged or assigned to new positions in the tray, the automation files for the show using those slides must be updated.
11. Add slides to carousel trays with the images upside down, with the correct (i.e., readable) side facing the lamp. Wess mountings should consistently show along the top of the tray either the serrated finger-openings (horizontal image) or the circular notch (vertical image).
12. Spare lamps are kept in the projection booth. If a lamp burns out during a show, manually turn off the projector and replace the lamp. After the projector is turned back on again, the automation system will automatically advance the projector to the slide where it should be at that time.

Informational Projectors

1. The informational system consists of three slide projector dissolve-pairs, designated as left, center and right. This system supplies the bulk of the visual material making up a typical planetarium presentation.

1. The informational projection system spans approximately 120 degrees of the dome azimuth, centered at the focus of the audience viewing area. The vertical center of these projections lies midway up the dome, to provide comfortable and unobstructed viewing for the audience.
2. These program projectors can also be used by science faculty for ordinary slide shows in the planetarium theater on any subject (even without the star projector).
3. Informational Focal Length: 4 in.

Code	Description	Type	Unit	Slot	PP
IRA	Informational Right A	SP	3	1	22
IRB	Informational Right B	SP	3	2	22
ICA	Informational Center A	SP	4	1	21
ICB	Informational Center B	SP	4	2	21
ILA	Informational Left A	SP	5	1	27
ILB	Informational Left B	SP	5	2	27
INFA	Informational Group A	GP	NA	NA	NA
INFB	Informational Group B	GP	NA	NA	NA

Panorama Projectors

1. Panoramas often are used to project a low, wide image of an edge (or chord) of a planet below, as it might appear from orbit. Panoramas also provide a basis for complementary video special effects, such as a moving space shuttle or telescope shown above an Earth panorama, or a video of a solar flare projected above a Sun panorama.
2. We will often use pans to show constellation figures as the constellation rises in the east.
3. The panorama projection system spans approximately 180 degrees of the dome horizon, centered at the focus of the audience viewing area. Each panorama consists of three panels, overlapping 25% to conform to multi-image industry standards.
4. Each panel consists of projector dissolve pairs, providing panorama crossfade capability.
5. Each projector can be individually controlled, allowing any projector in the pan system to stand alone and present individual images.
6. Panorama Focal Length: 2 in.

Code	Description	Type	Unit	Slot	PP
PRA	Panorama Right A	SP	3	3	22
PRB	Panorama Right B	SP	3	4	22
PCA	Panorama Center A	SP	4	3	21
PCB	Panorama Center B	SP	4	4	21
PLA	Panorama Left A	SP	5	3	27
PLB	Panorama Left B	SP	5	4	27
APAN	Panorama Group A	GP	NA	NA	NA
BPAN	Panorama Group B	GP	NA	NA	NA

To Pan or Not to Pan? Info's vs. Pan Projectors

Since Pans give a bigger field of view, why use Informationals at all?

1. Horizontal vs. Vertical
   Pans show only horizontal images (vertical images will drop below the dome and show on the wall, and may be cut off overhead). If a series of related slides includes any vertical images, the entire series must be put in Informational projectors.
2. Resolution and Brightness
   As a general rule, pan images are projected at a rather dim intensity (e.g., about 20 or 30%). The lateral pan images (left and right) are reflected through mirrors, which makes them more difficult to keep in a clear, precise focus. Generally, due to the curvature of the dome, only the lower third of a horizontal pan image will be in focus anyway (despite our special lenses, which compensate for the curvature to some degree). The bottom line is that if a series of related slides includes any that require bright illumination or that depict details necessitating a clear and precise focus, then put the entire series in Informational projectors rather than pans.
3. Dissolve Pairs vs. Dissolve Triplets
   All other things being equal, the Informational projectors are better suited for dissolve pairs, since they are aligned together. In contrast, the Pan fields of view are aligned in groups of three, abutting, rather than aligned with their corresponding field of view. In other words, PCA is aligned with PLA and PRA rather than with PCB. If there is a sequence of slides that includes one or more dissolve pairs, put them all in Informationals unless there is some reason why they must be in pans. Conversely, when switching between panorama scenes, it is usually best to fade through black (unless the scenes are quite similar).
4. Visibility
   Informationals are easily visible to all seats, whereas Pans are only partially visible. With a pan, the only thing that matters is that much of it is visible from any given seat. All other things being equal, if it is crucial that everyone see the entire image, put it in an Informational rather than a Pan.

Wide Angle Projectors

1. The wide angle projection system span a large vertical portion of the dome, almost 90 degrees from the springline to the zenith, centered at the focus of the audience viewing area.
2. The projected images of this two-field system includes most viewer's peripheral vision, effectively enveloping the participant with a single visual.
3. Sample use: Any towering image, such as tall forest trees in conjunction with snow special effect projectors above a panorama of a winter scene.
4. Wide Angle Focal Length: 1.4 in.

Code	Description	Type	Unit	Slot	PP
TN	Top North	SP	6	1	16
TS	Top South	SP	6	1	16
TG	Top Group	GP	NA	NA	NA

Special Projectors

1. Three 'special' projectors are included to help fill out the viewing area and add interest to the scene. These projectors are singles, not dissolve pairs.
2. Typically, 'specials' are oriented outside the normal field of view, and are used to provide orientation hints to the audience and direct their attention to objects of interest outside of their normal forward-looking cone of view.
3. Special Focal Length: 3 in.

Code	Description	Type	Unit	Slot	PP
SPE	Special East	SP	6	3	21
SPN	Special North	SP	1	1	15
SPS	Special South	SP	2	1	3
SPG	Special Group	GP	NA	NA	NA

Slew Zoom Rotator Projection

1. Phase II: Not yet installed at OBU.
2. A slew-zoom-rotator projector adds motion to the images in the environment. The range of motion allows the producer to place images in unexpected parts of the dome and move them through a travel that far exceeds the dimensions of a video image.
3. This special purpose projector is very versatile, combining the functionality of many separate devices into one combined package. A device such as this is instrumental in adding interest and preventing a presentation from becoming sterile.

All-Sky System

1. Not possible in a small planetarium without an elevator for the star projector.
2. 6 slide projectors with wide-angle lenses (like our Top North and Top South projectors), located around the circumference of the gallery at 60 degrees intervals, mounted in 6 rigid, anchored projection racks.
3. Each projector location is assigned a number from 1 to 6, beginning with due south.
4. This "all-sky" set of slide projectors fills the entire dome with a composite image; e.g., the cockpit of a spaceship, a full-view of a galaxy or nebula, or a map of constellations and other celestial objects superimposed upon the starfield. In addition to its routine use in planetarium shows, dissolving from one all-sky image to another can effectively demonstrate many concepts in general science.
5. Through whole-dome ("all-sky") projection, students might explore the scales of magnitude of powers of ten, dissolving up from quarks to atoms to people to stars to galaxies to galactic strings and back down again.
6. A series of whole-dome images could be used to present a guided tour of the biochemistry and large structures of a cell, as seen from the inside.
7. Look up from the center of a volcano (using a whole-dome projection image), then tour volcanoes and volcanic phenomena throughout the solar system. Or, similarly, tour the meteorological phenomena of various planetary bodies, including Earth.

| Top | ©1997