Optoma BX-CTA12 Zoom Standard-Throw Lens Guide: Compatible with ZK1000 ZK1120 ZK1320

Optoma Original Lens BX-CTA12 Zoom is an original optical accessory for Optoma professional projectors. It is a standard-throw lens (Standard Throw) with a throw ratio of 0.90-1.30:1. The manufacturer's compatibility list covers 3 models. Before installation, simply verify the projector model and panel size—there is no need to make do with an adapter ring. The value of an original lens lies not in the extra rows of specifications, but in the fact that it is calibrated at the factory to the optical path and mount of that projector series: once installed, the image circle, edge illumination, and focusing travel are all at their designed values, so there is no need to use keystone correction to compensate for image quality.

I. Lens Specifications

Brand	Optoma (Optoma)
Lens Model	BX-CTA12 Zoom
Throw Ratio	0.90-1.30:1
Product Type	Standard Throw (Standard Throw)
Compatible Models	3 models
Warranty	12 months; after-sales service is available for damage not caused by the user, based on the date shown on the sales invoice

These specifications are subject to the manufacturer's specifications. For mechanical dimensions, flange distance, and mount type not shown in the specification table, please verify them with us using the projector model. Placing an order based solely on a similar model carries the risk that the lens may not fit.

II. Calculating Installation Distance from Throw Ratio

The throw ratio is the ratio of the installation distance to the image width. This original lens is a zoom lens (0.90-1.30:1), so a given image size corresponds to a range of distances. Focus can be achieved anywhere within this range during installation.

Image Size	Image Width	Required Installation Distance
100 inches	2.15 m	Approx. 1.94 – 2.79 m
120 inches	2.58 m	Approx. 2.32 – 3.35 m
150 inches	3.22 m	Approx. 2.90 – 4.19 m
200 inches	4.30 m	Approx. 3.87 – 5.59 m

The distances above are the clear distances from the front surface of the lens to the screen and do not include space behind the projector for ventilation or cable connections. These figures are based on a 16:10 image; actual distances should be verified through on-site measurement and the manufacturer's manual.

Image quality differs at the two ends of the zoom range: at the close end, the image is brighter and the edges are slightly softer; at the far 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 on the focus ring, and then fine-tune the lens shift.

III. Compatible Models (3 Models)

The table below is taken from the manufacturer's compatibility list. Brightness and resolution have been populated from the model database; values that are unavailable are marked “—” and are not estimated.

Model	Brightness	Resolution
ZK1000	10000 lumens	3840x2400
ZK1120	11500 lumens	4K (3840 x 2160)
ZK1320	13500 lumens	4K (3840 x 2160)

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

Throw Ratio by Projector Series

The rated throw ratio of the same BX-CTA12 Zoom varies by projector series. For selection, use the value for the series of the actual projector.

Projector Series	Throw Ratio
—	0.90-1.30:1

IV. Three Checks Before Replacement

• Confirm the projector chip and resolution. The 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 first. The rated throw ratio of this lens is 0.90-1.30:1. Use the table in Section 2 to apply it to the dimensions of your installation site. A fixed-focus lens offers no adjustment margin, and even a zoom lens requires 10–20 cm of margin at both ends.
• Check the mount and locking mechanism. The original lens is calibrated to the mount of that projector series, and you must hear it lock into place after installation. A skewed image or soft edges are most often caused by an incompletely locked lens, rather than a problem with the lens itself.

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