Optoma BX-CTA10 Short Zoom Lens for ZK1000, ZK1120, ZK1320

Optoma Genuine Lens BX-CTA10 Short Zoom is an OEM optical accessory for Optoma professional projectors. It is a short-throw (Short Throw) lens with a throw ratio of 0.50-0.65:1. The official compatibility list covers 3 models. Before installation, simply verify the projector model and panel size; there is no need to make do with adapter rings. The value of a genuine lens lies not in the extra 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 as designed, with no need to use keystone correction to compensate for image quality.

1. Lens Specifications

The above specifications are subject to the official specifications. Mechanical dimensions, flange distance, and mount type are not included in the specification table. Please verify them with us according to the projector model; ordering solely because the model numbers are similar carries the risk that the lens will not fit.

2. Converting Throw Ratio to Installation Distance

The throw ratio is the ratio of the installation distance to the image width. This genuine lens is a zoom lens (0.50-0.65:1), so a given image size corresponds to a range of installation distances; it can focus at any point within that range.

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

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

3. Compatible Models (3 Models)

The table below is taken from the official compatibility list. Brightness and resolution are populated from the model database; where the data is unavailable, “—” is shown, with no values estimated.

To verify whether a model outside the list can be used, please send us photos of the projector nameplate and the existing lens. Platforms from the same generation often share the same mount, but the risk of ordering based solely on a similar model is not worth taking.

Throw Ratios for Different Model Series

The rated throw ratio varies by the model series on which the same BX-CTA10 Short Zoom is installed. When selecting a lens, use the value corresponding to the series of the projector in use.

4. Three Checks Before Replacement

• Check the projector chip and resolution. The genuine lens is designed for a specific panel size. If the panel specifications differ, the image circle cannot cover the image, resulting in vignetting or edge light falloff after installation.
• Calculate the installation distance first. This lens has a rated throw ratio of 0.50-0.65:1. Use the table in Section 2 to calculate the distance based on your site dimensions. A fixed-focus lens provides no adjustment margin, and even a zoom lens requires an additional 10–20 cm at both ends.
• Verify the mount and locking mechanism. The genuine lens is calibrated to the mount used on projectors in that series. After installation, you must hear the lock engage fully. A skewed image or soft edges are usually caused by incomplete locking, not by a problem with the lens itself.

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