Optoma BX-CTA18 Short Zoom Standard-Throw Lens Guide: WU1500 ZU1700 ZU1900 ZU2200

Optoma Original Lens BX-CTA18 Short Zoom is an OEM optical accessory for Optoma engineering projectors. It has a standard throw (Standard Throw) and a throw ratio of 0.84-1.02:1. The OEM compatibility list covers 4 models. Before installation, simply verify the projector model and panel size; there is no need to make do with adapter rings. The value of an OEM lens lies not in the extra rows of figures in a specification sheet, but in the fact that it is calibrated at the factory to the optical path and lens mount of the corresponding projector series. Once installed, the image circle, edge illumination, and focus travel all meet their design specifications, eliminating the need to use keystone correction to compensate for image quality.

1. Lens Specifications

These specifications are subject to the original manufacturer’s specifications. For mechanical dimensions, flange distance, and mount type not listed in the specification table, please contact us with the exact projector model. Ordering based solely on 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 OEM lens is a zoom lens (0.84-1.02:1), so a single image size corresponds to a range of installation distances. The lens can be focused at any position within this range.

These figures represent the clear distance from the front of the lens to the screen and do not include space behind the projector for cooling and cabling. They are calculated for a 16:10 image; actual distances should be verified on site and confirmed against the manufacturer’s manual.

Image quality varies between 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 the venue allows, it is recommended to use the middle of the range. After installation, first find the sharpest image using the focus ring, then fine-tune the lens shift.

3. Compatible Models (4 Models)

The table below is taken from the OEM compatibility list. Brightness and resolution are reproduced from the model database; values that cannot be obtained are shown as “—” and are not estimated.

For models not on the list, please send us photos of the projector nameplate and the existing lens so we can verify compatibility. Platforms of the same generation often share a lens mount, but the risk of ordering based on a similar model is not worth taking.

Throw Ratios by Model Series

The nominal throw ratio of the same BX-CTA18 Short Zoom varies across the series listed below. Select the value that corresponds to the actual projector series.

4. Three Checks Before Replacement

• Confirm the projector chip and resolution. Each OEM 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 edge light loss after installation.
• Calculate the installation distance first. This lens has a nominal throw ratio of 0.84-1.02:1. Use the table in Section 2 to calculate the distance for your venue dimensions. A fixed-focus lens offers no adjustment margin, and even a zoom lens requires 10–20 cm of allowance at both ends of the range.
• Verify the mount and locking mechanism. Each OEM lens is calibrated to the lens mount of the corresponding projector series. After installation, you must hear the lens lock into place. Image skew or soft edges are usually caused by incomplete locking, rather than a problem with the lens itself.

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