Optoma BX-CTA20 Semi-Wide Zoom Standard-Throw Lens for 9 Models

Optoma Genuine Lens BX-CTA20 Semi-Wide Zoom is an official optical accessory for Optoma professional projectors, offering a standard throw ratio of 1.20-1.50:1. The official compatibility list covers 9 models; before installation, simply verify the projector model and panel size, with no need for an adapter ring workaround. The value of a genuine lens lies not in the extra rows of specifications, but in its factory calibration to the optical path and lens mount of the relevant series: once installed, the image circle, edge illumination, and focusing travel all match the design specifications, eliminating the 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 specifications table, please contact us with the exact projector model. Placing an order solely because the model is similar carries the risk that the lens will not fit.

2. Calculating Installation Distance from the Throw Ratio

The throw ratio is the ratio of installation distance to image width. This genuine lens is a zoom lens (1.20-1.50:1), so a given image size corresponds to a range of installation distances, and focus can be achieved at any position within that range.

These figures represent the clear distance from the front face of the lens to the screen and do not allow for ventilation or cable connections behind the projector. They are calculated for a 16:10 image; actual distances should be verified through on-site measurement and in accordance with the manufacturer's manual.

Image quality differs at the two ends of the zoom range: near the close end, the image is brighter and the edges are slightly softer; near the long-throw end, the edges are sharper and brightness is slightly lower. Where venue conditions allow, use a position near the middle of the range. After installation, first find the sharpest setting on the focus ring, then fine-tune the lens shift.

3. Compatible Projector Models (9 Models)

The following table is taken from the manufacturer's compatibility list. Brightness and resolution are populated from the model database; unavailable figures are marked — without speculation.

To determine whether a model outside the list is supported, send us photos of the projector nameplate and the existing lens for verification. Platforms of the same generation often share the same lens mount, but the risks of ordering based on a similar model are not worth taking.

Throw Ratios by Projector Series

The nominal throw ratio varies by series when the same BX-CTA20 Semi-Wide Zoom is installed. Select the value corresponding to the series of the actual projector.

4. Confirm Three Things Before Replacement

• Confirm the projector imaging chip and resolution. Genuine lenses are designed for specific panel sizes. When the panel specifications differ, the image circle cannot cover the full panel, resulting in vignetting or light loss at the edges after installation.
• Calculate the installation distance first. The nominal throw ratio of this lens is 1.20-1.50:1. Apply the table in Section 2 to your installation site's dimensions. Fixed-focal-length lenses provide no adjustment margin, while zoom lenses still require a 10–20 cm margin at both ends of the range.
• Verify the mount and locking mechanism. Genuine lenses are calibrated for the lens mounts of the corresponding projector series. After installation, you must hear the lens click into the locked position. Most cases of image skew or soft edges result from incomplete locking, not a problem with the lens itself.

If you are unsure, take one photo each of the projector nameplate and the nameplate on the existing lens and send them to us. Verification against the actual items is the safest approach.