Optoma BX-CTA07 Zoom Standard Throw Lens Guide for ZK1120 and ZK1320

Optoma Genuine Lens BX-CTA07 Zoom is an original optical accessory for Optoma professional projectors. It is a standard-throw (Standard Throw) lens with a 1.30-1.80:1 throw ratio. The official compatibility list covers 2 models. Before installation, simply verify the projector model and panel size; no adapter ring workaround is needed. The value of an original lens lies not in extra rows of specifications, but in the fact that it is factory-calibrated for the optical path and lens mount of that model series. Once installed, image circle coverage, edge illuminance, and focus travel all meet their design values, eliminating the need for keystone correction to compensate for image quality.

1. Lens Specifications

The above specifications are subject to the official manufacturer specifications. For mechanical dimensions, flange distance, and mount type not shown in the specification table, please contact us with the projector model for verification. Placing an order solely because the model numbers are similar carries the risk of an incompatible fit.

2. 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 (1.30-1.80:1), so each image size corresponds to a range of installation distances. It can be focused anywhere within that range.

The distances above are the clear distances from the front of the lens to the screen and do not include space for rear housing cooling and cabling. These figures are calculated for a 16:10 image; actual distances are subject to on-site measurement and the manufacturer's manual.

Image quality varies at the two ends of the zoom range: the image is brighter and the edges are slightly softer at the short-throw end, while the edges are sharper and brightness is slightly lower at the long-throw end. Where site conditions allow, use the midpoint of the range. After installation, find the sharpest position on the focus ring, then fine-tune the lens shift.

3. Compatible Models (2 Models)

The following table is taken from the official compatibility list. Brightness and resolution are populated from the projector model database; where the data is unavailable, “—” is shown, and no assumptions are made.

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

Throw Ratio by Projector Model Series

The nominal throw ratio varies by series when the same BX-CTA07 Zoom is installed. Select the ratio based on the series of the actual projector.

4. Three Checks Before Replacement

• Confirm the projector imaging chip and resolution.Original lenses are designed for a specific panel size. If the panel specifications differ, the image circle cannot provide full coverage, resulting in vignetting or edge light loss after installation.
• Calculate the installation distance first.This lens has a nominal throw ratio of 1.30-1.80:1. Use the table in Section 2 to calculate the distance for your venue. A fixed-focus lens provides no adjustment range, while a zoom lens should also have an additional 10–20 cm at both ends of the range.
• Verify the mount and locking mechanism.Original lenses are calibrated to the mount used on that model series. After installation, you must hear the lens lock into place. A skewed image or soft edges are usually caused by incomplete locking, not by a fault in the lens.

If you are uncertain, send us one photo each of the projector nameplate and the existing lens nameplate. Verification against the physical equipment is the most reliable approach.