Christie 121-113106-XX Medium Zoom Long-Throw Lens for LW401 LW551i LWU421 LWU501i LX501

Christie Original Lens 121-113106-XX Medium Zoom is an OEM optical accessory for Christie professional projectors. It is a long-throw lens (Long Throw) with a throw ratio of 1.50-3.00:1. The official compatibility list covers 5 models. Before installation, simply verify the projector model and panel size; no adapter rings are needed. The value of an original lens lies not in the additional rows it adds to a specification sheet, but in the fact that it is factory-calibrated to the optical path and mount of the projector series. Once installed, the image circle, edge illumination, and focus travel are all set to 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 official product specifications. For mechanical dimensions, flange distance, and mount type not shown in the specifications table, please contact us with 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

The throw ratio is the ratio of installation distance to image width. This original lens is a zoom lens (1.50-3.00:1), so each image size corresponds to a range of installation distances. The lens can be focused anywhere within that range during installation.

These figures represent the clear distance from the front surface of the lens to the screen and do not include clearance at the rear of the projector for heat dissipation and cable connections. The calculations are based on a 16:10 image; actual values should be verified through on-site measurements and the official manual.

Image quality differs at the two ends of the zoom range: the image is brighter and the edges are slightly softer near the close end, while the edges are sharper and brightness is slightly lower near the far end. When the venue allows, place the projector in the middle of the range. After installation, use the focus ring to find the sharpest image position, then fine-tune the lens shift.

III. Compatible Models (5 Models)

The following table is based on the official compatibility list. Brightness and resolution are populated from the model database; unavailable specifications are shown as “—” and are not estimated.

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

Throw Ratios by Projector Series

The nominal throw ratio of the same 121-113106-XX Medium Zoom lens varies depending on the projector series it is installed on. Select the value based on the series of the actual projector.

IV. 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 cover the full image, resulting in vignetting or edge light loss after installation.
• Calculate the installation distance first. The nominal throw ratio of this lens is 1.50-3.00:1. Use the table in Section II to match the dimensions of your venue. Fixed-focus lenses offer no adjustment margin, while zoom lenses should also allow a 10–20 cm margin at both ends.
• Verify the mount and locking mechanism. Original lenses are calibrated to the mount of the relevant projector series and must audibly lock into place after installation. A skewed image or soft edges are usually caused by incomplete lens locking rather than a problem with the lens itself.

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