Optoma BX-CTA26 Zoom Standard-Throw Lens: ZK1050 & ZK750 Compatibility

Optoma Genuine Lens BX-CTA26 Zoom is an original optical accessory for Optoma professional projectors. It is a standard-throw lens (Standard Throw) with a throw ratio of 1.20-1.73:1. The official compatibility list covers 2 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 extra rows of specifications, but in the fact that it is factory-calibrated to the optical path and mount of the corresponding model series. Once installed, the image circle, edge illumination, and focusing travel are all at their intended design values, with no need to use keystone correction to compensate for image quality.

1. Lens Specifications

These specifications are subject to the manufacturer's official specifications. For mechanical dimensions, flange distance, and mount type not listed in the specification table, please contact us with the exact projector model for verification. Ordering solely based 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 the installation distance to the image width. This genuine lens is a zoom lens (1.20-1.73:1), so a given image size corresponds to a range of installation distances, and the lens can be focused anywhere within that range.

These figures represent the clear distance from the front of the lens to the screen, excluding space behind the chassis for cooling and cable connections. They are calculated for a 16:10 image; actual values depend on on-site measurements and the manufacturer's manual.

Image quality differs at the two ends of the zoom range: the image is brighter and the edges are slightly softer toward the short end, while the edges are sharper and brightness decreases slightly toward the long end. Where the venue allows, use the middle of the range. After installation, find the sharpest setting on the focus ring, then fine-tune the lens shift.

3. Compatible Models (2 Models)

The following table is taken from the manufacturer's compatibility list. Brightness and resolution are populated from the model database; values that cannot be obtained are shown as “—” rather than estimated.

To check whether a model outside the list is supported, send us photos of the projector nameplate and the existing lens for verification. Platforms from the same generation often share the same mount, but it is not worth the risk of ordering based solely on a similar model.

Throw Ratio by Model Series

The rated throw ratio differs among the series listed below when the same BX-CTA26 Zoom is installed. Select the value based on the series of the actual projector.

4. Three Checks Before Replacement

• Confirm the projector imaging chip and resolution. Genuine lenses are designed for a specific panel size. If the panel specification differs, 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 rated throw ratio of 1.20-1.73:1. Apply the table in Section 2 to your venue dimensions. Fixed-focus lenses offer no adjustment range, and zoom lenses should also allow for 10–20 cm of extra margin at both ends.
• Verify the mount and locking mechanism. Genuine lenses are calibrated to the mount of the corresponding model series. You must hear the lens lock into place after installation. A skewed image or soft edges usually indicate that the lens is not fully locked 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 and send them to us. Verification against the actual hardware is the safest approach.