Optoma BX-CTA08 Zoom Standard Throw Lens Overview: Compatible with ZK1000 ZK1120 ZK1320

Optoma Original Lens BX-CTA08 Zoom is an original optical accessory for Optoma professional projectors. It is a standard-throw lens (Standard Throw) with a throw ratio of 1.25-2.00:1. The official compatibility list covers three models; before installation, simply verify the projector model and panel size—no need to improvise with adapter rings. The value of an original lens lies not in a few extra figures on the specification sheet, but in the fact that its optical path and mount are calibrated at the factory for that projector series: once fitted, the image circle, edge illumination, and focusing travel are all engineered values, so there is no need to compensate for image quality with keystone correction.

I. Lens Specifications

Brand	Optoma（Optoma）
Lens Model	BX-CTA08 Zoom
Throw Ratio	1.25-2.00:1
Product Type	Standard throw (Standard Throw)
Compatible Models	3 units
Warranty	12 months; non-user-caused damage is eligible for after-sales service, subject to the date on the shipping invoice

The above specifications are subject to the manufacturer's specifications. For mechanical dimensions, flange distance, and mount type not shown in the specification table, please check with us using the projector model; ordering directly based on a similar model carries the risk that the lens will not fit.

II. Converting Throw Ratio into Installation Distance

The throw ratio is the ratio of the installation distance to the image width. This original lens is a zoom lens (1.25-2.00:1), so a single image size corresponds to a range of distances; any installation position within this range can be brought into focus.

Image Size	Image Width	Required Installation Distance
100 inches	2.15 m	approx. 2.69 – 4.30 m
120 inches	2.58 m	approx. 3.22 – 5.16 m
150 inches	3.22 m	approx. 4.03 – 6.45 m
200 inches	4.30 m	approx. 5.38 – 8.60 m

The distances above are clear distances from the front of the lens to the screen and do not allow for rear chassis cooling or cabling space. They are calculated for a 16:10 aspect ratio; actual installation should be based on on-site measurements and the manufacturer's manual.

Image quality differs at the two ends of the zoom range: toward the close end, the image is brighter and the edges appear slightly softer; toward the wide end, the edges are crisper and brightness drops slightly. Where venue conditions allow, it is recommended to position the lens around the middle of the range. After installation, first find the sharpest position on the focus ring, then fine-tune the lens shift.

III. Compatible Models (3 Units)

The table below is taken from the manufacturer's compatibility list; brightness and resolution are populated from the model database. Entries that cannot be verified are marked '—' and are not guessed.

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

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

Throw Ratios for Different Model Series

The rated throw ratio of the same BX-CTA08 Zoom varies across the series listed below, so select the value according to the series of the actual projector.

Model Series	Throw Ratio
—	1.25-2.00:1

IV. Confirm Three Things Before Replacement

• Confirm the projector's imaging panel and resolution. The original lens is designed for a specific panel size. When the panel specifications differ, the image circle cannot cover the full frame, resulting in vignetting or edge light loss after installation.
• Calculate the installation distance first. This lens has a rated throw ratio of 1.25-2.00:1; use the table in Section II to work it out against 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.
• Check the mount and locking mechanism. The original lens is calibrated to the mount of that projector series, and you must hear it click into the locked position after fitting. A skewed image or soft edges are usually caused by incomplete locking, not by the lens itself.

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