Alice’s Trip: Projection on a Budget 2

This is a follow-up to last week’s post concerning the ongoing planning of a projection element for the upcoming production of Alice’s Trip at Theatre Simpson.

At the moment we have identified 2 projectors which we intend to use for the side screens.  These projectors are  PowerLite Epson 6110i projectors. PowerLite 6110i Specifications Sheet (PDF). Since our budget is tight, we need to make them work.  They are rated to produce 3500 lumens.  This is bright compared to the standard classroom-style projector, but since theatrical projectors are often rated at 5000 to 10,000 lumens according to the panel from 1012 USITT workshop Static and Video Projection of Scenery on your Stage they will not be overly bright.  Therefore, we need to maximize their impact.  This can be done by placing them as close to the screen as the optics will permit  and by utilizing as much of their image as efficiently as possible.

Image of aspect ratio of screen in landscape orientationTo the left is a diagram that illustrates the size an aspect ratio of these projectors used in the traditional landscape format.  The pale yellow square indicates the 4×3 native aspect ratio of the projector.  In order to achieve the 13′-9″ height of the screen, the projector must be approximately 28′-8″ from the screen.  Notice that this results in a width of approximately 18′-4″ and a whole lot of wasted image and loss of brightness.

Image of S.R. Screen for Alice in Portrait orientationMeanwhile, the illustration to the right shows the same screen and projector.  The difference is that the projector is placed upon its side generating a 3×4 aspect ratio.  In this case, the projector can be as close as 25′ from the screen.  In addition to a reduction in the backstage distance needed for this effect, the closer proximity harnesses a greater percentage of the available lumens by utilizing a larger percentage of the projected image area.

image of a plan of backstage showing the projector for the SR ScreenThe plan to the left illustrates both throw distances.  Notice that the 25′ distance illustrated by the green lines and representing the side-mounted portrait-formatted projection barely fits in the available backstage space. Meanwhile the 28′-9″ throw distance of the landscape-oriented projector (shown in blue) exceeds the available backstage space.  The illustration conjectures the use of a mirror to bend the projected image, effectively increasing the throw distance.  It is also possible to replace the standard zoom lens provided with the projectors with a short-throw lens.  However, since we don’t currently own such lenses, the additional cost to purchase or to rent them is prohibitive.

The central screen offers additional challenges.  The first challenge is that we have yet to identify a projector for it.  Since we will have to rent or borrow this projector, this fact may give us some flexibility, including the possibility of renting a brighter projector and/or a wide-angle lens. Another challenge is the fact that like the side screens, this screen is also taller than it is wide as seen to the right.  Therefore, it also does not conform to the standard native landscape format of most projectors.  At approximately 16′ high x 12′ wide, it is about the same aspect ratio as a standard projector except that this orientation requires the center  projector to be mounted sideways as well (complicating the content creation).  The center screen hangs 19′ downstage of the backstage wall.  Since projectors with standard lenses (such as the two Epson projectors already identified) require a full 25′ to project an image of 16′ x 12′, I calculate that in addition to mounting the projector on its side, we will need to reflect the image off a mirror of approximately 3’6″ wide and nearly 4′-8″ high mirror in order to achieve the appropriate size.  This is illustrated in the floor plan above and to the left.

Though landscape format (as shown at right) would simplify the installation by allowing us to mount the projector in its standard way, the throw distance required is about 33′-4 and this would require a mirror of around 8′-0″ width and 4′-9″ height.  Since such a mirror is prohibitively large, and since a large percentage of the available brightness would be falling outside of the screen (and would, therefore, be wasted), this option is probably not feasible.

We are also exploring our front-projection options for the center screen.  Used as a front projection screen, both the fabric of the rear projection screen and the light-colored profile flat representing swagged drapery that surrounds it could serve as a single projection surface. The front of the lighting booth (as seen in the section view ab0ve) offers the most likely position for a  projector to be mounted in order to project images on this surface.  At that position, the throw would be around 55′. If we do use this position, the standard
medium/long throw zoom lens should be able to project the needed 18′ high x 16′ wide image.  If the projector were installed in normal landscape orientation, the image would be 24′ wide in order to achieve the needed 18′ height.

An unfortunate consequence of this is that the edges of the projected image in landscape orientation extend well past the edges of the composite projection surface.  While this would mean that some of the image would fall upon black drapes and probably not be too much of a distraction, the placement of the side screens is likely to cause them to catch this extra image width, resulting in unsightly distraction.  This is illustrated in the plan above and to the left.

By orienting the front-projection projector mounted on the booth-front position on its side we can limit the problems caused by the edges of the landscape-oriented image and zoom the image to correspond to the 16′ width of the central projection surface (as shown in the diagram to the left).  In this case, the extra image would fall above, and/or below the projection surface and avoid catching the side screens altogether.

We can see, therefore that the most efficient use of all 3 projectors will be in portrait orientation.  While the projectors for the side screen will definitely be behind the screens providing rear projection, we have the option of projecting from either the front or the rear for the center screen/projection surface.  It is unclear to me what problems this side-mounting of the projectors might cause with their proper operation.  However, considering the shape of all of the screens (all being higher than they are wide) and the need to maximize the lumen output of the fairly dim non-theatrical grade projectors, I do not see an alternative.  Only time will tell if this will work.

In a later post, I intend to explore some of the software that we might use to deliver content to the projectors, as well as to describe and link to some very powerful software for theatrical projection that we will not be able to employ for this project owing to the cost that accompanies such powerful and specialized programs.

Meanwhile, that’s enough for now! Have fun!  But be safe!

SJM

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