BenQ LS1ST1 Wide Zoom Standard-Throw Lens Review: LU9915 Compatibility

BenQ Original Lens LS1ST1 Wide Zoom is an original optical accessory for BenQ business projectors. It is a standard-throw lens (Standard Throw) with a throw ratio of 1.25:1 - 1.79:1. The official compatibility list covers 1 model; before installation, simply verify the projector model and panel size, with no need to force compatibility using adapter rings. The value of an original lens lies not in the additional rows of specifications, but in the fact that its optical path and mount are calibrated at the factory for that model series: once installed, the image circle, edge illumination, and focusing travel all meet their design values, so there is no need to compensate for image quality with keystone correction.

1. Lens Specifications

The above specifications are subject to the manufacturer's official specifications. For mechanical dimensions, flange distance, and mount type not listed in the specification table, please provide your projector model for verification. Ordering solely on the basis of a similar model carries the risk that the lens will not fit.

2. Calculating Installation Distance from Throw Ratio

The throw ratio is the ratio of installation distance to image width. This original lens is a zoom lens (1.25:1 - 1.79:1), so a given image size corresponds to a range of installation distances, and the lens can focus anywhere within that range.

These figures represent the clear distance from the front of the lens to the screen and do not include space for rear projector ventilation or cable connections. They are calculated for a 16:10 image; actual values must be confirmed through on-site measurements and the manufacturer's manual.

Image quality differs at the two ends of the zoom range: toward the short-throw end, the image is brighter and the edges are slightly softer; toward the long-throw end, the edges are sharper and brightness decreases slightly. Where site conditions allow, use the middle of the range. After installation, first find the sharpest position using the focus ring, then fine-tune the shift.

3. Compatible Models (1 Model)

The table below is taken from the official compatibility list. Brightness and resolution have been populated from the model database; where unavailable, they are marked “—” and have not been estimated.

To verify compatibility with a model not on the list, send us photos of the projector nameplate and current lens. Platforms of the same generation often share mounts, but ordering based on a similar model is not worth the fit risk.

Throw Ratios by Model Series

The rated throw ratio of the same LS1ST1 Wide Zoom varies across the series listed below. Select the value based on the series of your projector.

4. Three Checks Before Replacement

• Confirm the projector panel and resolution. Each original lens is designed for a specific panel size. If the panel specifications differ, the image circle cannot cover the full image, resulting in vignetting or light loss at the edges.
• Calculate the installation distance. This lens has a rated throw ratio of 1.25:1 - 1.79:1; use the table in Section 2 to calculate the distance for your installation space. Fixed-focus lenses offer no adjustment range, while zoom lenses should also allow an additional 10–20 cm at both ends.
• Verify the mount and locking mechanism. The original lens is calibrated to the mount of that model series and must audibly lock into place after installation. If the image is skewed or the edges are not sharp, the lens is usually not fully locked rather than the lens itself being defective.

If you are unsure, send us one photo each of the projector nameplate and the nameplate on your existing lens. Verification against the actual hardware is the most reliable approach.