BenQ LS1ST3 Wide Fixed Short-Throw Lens: LU9915 Compatibility

BenQ Original Lens LS1ST3 Wide Fixed is an original optical accessory for BenQ business projectors. It is a short-throw (Short Throw) lens with a throw ratio of 0.76:1. The official compatibility list covers one projector model; before installation, simply verify compatibility using the projector model and panel size, with no need to make do with an adapter ring. The value of an original lens lies not in the additional figures in the specification sheet, but in its factory calibration to the optical path and mount of that model series: once installed, the image circle, edge illumination, and focusing travel are all at their design values, so there is no need to use keystone correction to compensate for image quality.

I. Lens Specifications

The above specifications are subject to the manufacturer's official specifications. Mechanical dimensions, flange distance, and mount type that are not shown in the specification table should be verified with us according to the projector model. Ordering solely on the basis of a similar model carries the risk that the lens will not fit.

II. Converting Throw Ratio to Installation Distance

The throw ratio is the ratio of the installation distance to the image width. This original lens is fixed-focus (0.76:1), so the installation distance varies linearly with image size, with no adjustment margin. Accurate measurements are essential before installation.

These figures represent the clear distance from the front surface of the lens to the screen and do not include clearance behind the projector for heat dissipation and cable connections. They are calculated for a 16:10 image; actual values should be confirmed through on-site measurements and the manufacturer's manual.

III. Compatible Projector Models (1 projector)

The table below is taken from the official compatibility list. Brightness and resolution are populated from the model database; unavailable data is shown as “—” rather than estimated.

To determine whether a model outside the list can be used, please send us photos of the projector nameplate and the existing lens for verification—projector platforms from the same generation often use the same mount, but ordering based solely on a similar model is not worth the risk.

Throw Ratios by Projector Model Series

The nominal throw ratio differs when the same lens, LS1ST3 Wide Fixed, is used with the series listed below; select the value according to the series of the actual projector.

IV. Three Checks Before Replacement

• Confirm the projector chip and resolution. The original lens is designed for a specific panel size; if the panel specifications differ, the image circle cannot cover the panel, resulting in vignetting or light loss at the edges after installation.
• Calculate the installation distance first. This lens has a nominal throw ratio of 0.76:1; use the table in Section II to calculate the distance for your site dimensions. A fixed-focus lens has no adjustment margin, and even a zoom lens should have 10–20 cm of clearance at both ends.
• Verify the mount and locking mechanism. The original lens is calibrated to the mount of that model series, and you must hear it click into place after installation. A skewed image or poorly defined edges usually means the lock is not fully engaged, not that the lens itself is defective.

If you are unsure, take one photo of the projector nameplate and one of the existing lens nameplate and send them to us; verification against the actual equipment is the safest approach.