A venue has a fixed projector position nine metres from an inflatable movie screen. The screen’s usable image width is six metres. Can the projector fill that width from the available position? The answer depends on the lens’s throw ratio range and on how its manufacturer defines the measurement points.

Start with the image width

Use the width of the rectangle the projector is intended to fill. The outside width of an inflatable frame includes its supporting structure, and a diagonal measurement crosses the picture from corner to corner. Either figure can be useful when ordering a screen, but inserting it in the width field can give the wrong distance.

For instance, a fictional screen has a 6.8 m outside width and a 6.0 m usable image width. At a throw ratio of 1.50, those inputs produce distances of 10.2 m and 9.0 m respectively. The difference comes from choosing a different measurement, even though the arithmetic is correct in both cases. If a quotation gives only a diagonal, confirm the actual viewing dimensions. The inflatable screen aspect ratio guide covers picture format and viewing area.

Turn the lens range into a distance range

Throw ratio is the projection distance divided by the projected image width, using the same units for both. For a known width, multiply the width by the ratio to find the corresponding distance. Sony documents this relationship and directs users to the projector’s lens specifications. Sony throw distance calculation

Assume a fictional zoom lens lists a throw ratio from 1.20 to 1.80 for the proposed configuration. For a 6.0 m image width, the calculated range is 7.2 to 10.8 m. Each end represents a different optical zoom setting. If a lens lists a single fixed ratio, the same calculation gives one nominal distance for that width.

The numbers are illustrative. At 9.0 m the required ratio fits the assumed lens range. At 6.6 m even the lowest listed ratio produces an image narrower than 6.0 m. At 11.4 m even the highest listed ratio produces an image wider than 6.0 m. The comparison tells the planner whether the width can be reached optically from the proposed position.

Compare two ranges when the position can move

Some venues offer a band of possible positions instead of a single spot. Suppose the usable band runs from 10.4 to 11.5 m, using the same measurement points as the lens calculation. The 7.2–10.8 m optical range overlaps it from 10.4 to 10.8 m. This is the part of the available band to carry into the model-specific check. A lens calculation that just touches the venue limit leaves little room for measurement differences or a change in screen position.

Check the width available from a fixed position

The same relationship works in reverse. Divide the distance by the ratio to find the corresponding image width. At the fictional 9.0 m position, the 1.20 setting yields a width of 7.5 m and the 1.80 setting yields 5.0 m. The width interval runs from 5.0 to 7.5 m. The lower ratio produces the larger image at this fixed distance, so the endpoints reverse when converting the ratio range into a width range.

This reverse check helps when the venue position is fixed and the screen has yet to be specified. Compare the usable width of each proposed screen with the interval, then consult the manufacturer’s model limits. If the proposed screen changes after the site visit, recalculate from its actual image width before carrying the previous projector position into the revised plan.

Confirm the exact configuration in the manufacturer’s table

Use the table or calculator for the quoted projector and installed lens. A projector family can have several lens options. Look for the applicable image size range, the measurement reference and any configuration notes. Epson, for example, separates the wide and tele distance limits and shows lens-center offset separately in its model documentation. Epson LS12000 projection distance table

Measure to the projection surface and from the reference point shown for the model. A venue dimension taken from the rear of a projector table may use a different reference. Also check whether the table expresses image size as a diagonal for a stated aspect ratio. The ratio formula uses width, while a manufacturer’s lookup table may label its rows by diagonal.

Save the actual lens table with the venue measurements for the crew. Record the usable image width, proposed position, projector and lens identifiers, and the matching row or calculator result. This keeps the distance decision traceable when a rental package changes. For broader equipment choices see the outdoor cinema buyer’s guide and drive-in setup guide. Contact Ginflatables for screen dimensions.

Cover image: AI-generated editorial illustration.