Christie 121-129103-XX Zoom Standard Throw Lens for 17 Models incl. LHD720i-D BLACK, LW651i-D

Christie Original Lens 121-129103-XX Zoom is an OEM optical accessory for Christie professional projectors. It is a standard-throw lens (Standard Throw) with a 1.19-1.80:1 throw ratio. The OEM model compatibility list covers 17 compatible projector models. Before installation, simply verify the projector model and panel size; there is no need to resort to adapter rings or other workarounds. The value of an OEM lens lies not in the extra rows of numbers in the specification sheet, but in the fact that it is factory-calibrated to the optical path and mount of that projector series. Once installed, the image circle, edge illumination, and focus travel are all at their design values, so there is no need to use keystone correction to compensate for image quality.

I. 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 send us the projector model for verification. Placing an order based solely on a similar model carries the risk that the lens will not fit.

II. Calculating Installation Distance from Throw Ratio

A throw ratio is the ratio of installation distance to image width. This OEM lens is a zoom lens (1.19-1.80:1), so a given image size corresponds to a range of installation distances. The image can be focused anywhere within that range.

These distances represent the clear distance from the front surface of the lens to the screen and do not include clearance for cooling and cable connections at the rear of the projector. The figures are calculated for a 16:10 image; verify the actual distances on site and consult the manufacturer's manual.

Image quality varies at the two ends of the zoom range: near the short-throw end, the image is brighter but the edges are slightly softer; near the long-throw end, the edges are sharper but brightness is slightly lower. Where the venue allows, we recommend targeting the middle of the range. After installation, first find the sharpest position on the focus ring, then fine-tune the lens shift.

III. Compatible Projector Models (17 models)

The following table is taken from the OEM model compatibility list. Brightness and resolution have been populated from the model database; values that could not be obtained are shown as —, and no estimates have been made.

For models not on the list, please send us the projector nameplate and a photo of the existing lens for verification. Same-generation platforms often share a mount, but the risk of ordering based on a similar model is not worth taking.

Throw Ratios by Model Series

The nominal throw ratio varies when the same 121-129103-XX Zoom lens is installed on the following series. Use the ratio corresponding to the actual projector series when selecting a lens.

IV. Three Checks Before Replacement

• Confirm the projector imaging chip and resolution. OEM lenses are 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. This lens has a nominal throw ratio of 1.19-1.80:1. Apply the table in Section 2 to the dimensions of your installation site. A fixed-focus lens offers no adjustment margin, and even a zoom lens should allow for 10–20 cm at both ends.
• Verify the mount and locking mechanism. OEM lenses are calibrated to the mount of the corresponding projector series and must audibly click into the locked position after installation. Image skew or soft edges are usually caused by incomplete locking, rather than a problem with the lens itself.

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