Christie 121-115108-XX Ultra Long Zoom Lens Overview: 22 Compatible Projector Models

Christie Original Lens 121-115108-XX Ultra Long Zoom is an OEM optical accessory for Christie engineering projectors, featuring a long-throw design with a 4.90-8.30:1 throw ratio. The factory compatibility list covers 22 models. Before installation, simply verify the projector model and panel size; no adapter ring is needed. The value of an OEM lens lies not in the extra rows of specifications, but in the fact that it is calibrated at the factory to the optical path and mount of that projector series: once installed, image circle coverage, edge illumination, and focusing travel all match the design values, eliminating the need for keystone correction to compensate for image quality.

I. Lens Specifications

These specifications are subject to the original manufacturer’s specifications. For mechanical dimensions, flange distance, and mount type not shown in the specifications table, please verify them with us using the projector model. Placing an order based solely on a similar model carries the risk that the lens will not fit.

II. Calculating Installation Distance from the Throw Ratio

The throw ratio is the ratio of the installation distance to the image width. This OEM lens has a zoom range of 4.90-8.30:1, so each image size corresponds to a range of installation distances, and the lens can be focused at any distance within that range.

These figures represent the clear distance from the front of the lens to the screen and do not allow for ventilation and cabling space behind the projector. They are calculated for a 16:10 image; actual distances are subject to on-site measurements and the original manufacturer’s manual.

Image quality varies at the two ends of the zoom range: toward the near end, the image is brighter and the edges are slightly less crisp; toward the far end, the edges are sharper and the brightness is slightly lower. Where venue conditions allow, use the middle of the range. After installation, find the sharpest position on the focus ring first, then fine-tune the lens shift.

III. Compatible Models (22 Models)

The following table is taken from the original manufacturer’s compatibility list. Brightness and resolution are populated from the model database; unavailable values are marked as — and have not been estimated.

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

Throw Ratios by Projector Series

The nominal throw ratio of the same 121-115108-XX Ultra Long Zoom varies depending on the projector series it is installed on. Select the value based on the series of the projector in use.

IV. Three Checks Before Replacement

• Confirm the projector chip and resolution.OEM lenses are designed for specific panel sizes. If the panel specifications differ, the image circle cannot cover the full image, resulting in vignetting or light loss at the edges after installation.
• Calculate the installation distance first.This lens has a rated throw ratio of 4.90-8.30:1. Use the table in Section II to match it to your venue dimensions. Fixed-focus lenses provide no margin, and zoom lenses should also allow an additional 10–20 cm at both ends.
• Verify the mount and locking mechanism.The OEM lens is calibrated to the mount of this projector series. After installation, you must hear it lock fully into place. A skewed image or soft edges are usually caused by incomplete locking rather than a defect in the lens itself.

If you are unsure, photograph both the projector nameplate and the nameplate on the existing lens, then send the photos to us. Verification against the actual equipment is the most reliable approach.