Christie 121-136101-XX Short Zoom Lens Guide for LWU755-DS and LWU900-DS

Christie Original Lens 121-136101-XX Short Zoom is an OEM optical accessory for Christie professional projectors. It is a standard-throw lens (Standard Throw) with a throw ratio of 0.74-0.98:1. The OEM compatibility list covers 2 models. Before installation, simply verify the projector model and panel size; there is no need to resort to adapter rings. The value of an OEM lens lies not in the additional figures in its specification sheet, 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 as designed, with no need to compensate for image quality using keystone correction.

I. Lens Specifications

The above specifications are subject to the manufacturer’s original specifications. For mechanical dimensions, flange distance, and mount type not shown in the specification sheet, please verify them with us based on the projector model. Ordering directly based on a similar model carries the risk that the lens will not fit.

II. Calculating Installation Distance from Throw Ratio

The throw ratio is the ratio of the installation distance to the image width. This OEM lens is a zoom lens (0.74-0.98:1), so a given image size corresponds to a range of distances, and the lens can focus anywhere within that range during installation.

These distances represent the clear distance from the front of the lens to the screen and do not account for space behind the projector for heat dissipation and cable connections. They are calculated for a 16:10 image; actual values are subject to on-site measurements and the manufacturer’s manual.

Image quality varies at the two ends of the zoom range: near the close end, the image is brighter and the edges are slightly softer; near the long end, the edges are sharper and the image is slightly dimmer. When the venue allows it, it is recommended to place the projector in the middle of the range. After installation, find the sharpest setting on the focus ring before fine-tuning the lens shift.

III. Compatible Models (2 Models)

The following list is taken from the OEM compatibility list. Brightness and resolution are populated from the model database. Values that cannot be retrieved are shown as “—”, with no assumptions made.

For models not included in the list, please send us photos of the projector nameplate and the current lens so that we can verify compatibility. Platforms of the same generation often share mounts, but the risk of ordering based on a similar model is not worth taking.

Throw Ratios for Different Model Series

The rated throw ratio differs when the same 121-136101-XX Short Zoom is used with the series listed below, so select the value based on the series of the actual projector.

IV. Three Things to Confirm Before Replacement

• Confirm the projector 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 edge light loss after installation.
• Calculate the installation distance first.This lens has a rated throw ratio of 0.74-0.98:1. Use the table in Section II to calculate the distance for your venue. Fixed-focus lenses provide no adjustment margin, and zoom lenses still require 10–20 cm of clearance at both ends.
• Verify the mount and locking mechanism.OEM lenses are calibrated to the mounts of projectors in the relevant series. After installation, you must hear the lens click into the locked position. A skewed image or soft edges are usually caused by incomplete locking rather than a problem with the lens itself.

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