Christie 121-124108-XX Ultra Long Zoom Lens for 13 Projector Models

Christie Original Lens 121-124108-XX Ultra Long Zoom is an OEM optical accessory for Christie engineering projectors. It is a long-throw (Long Throw) lens with a throw ratio of 5.46-8.70:1. The official compatibility list covers 13 models; before installation, simply verify the projector model and panel size, with no need to resort to adapter rings. The value of an original lens lies not in the extra figures in its specification sheet, but in its factory calibration to the optical path and mount of that model series: once installed, the image circle, edge illumination, and focusing travel all meet their design values, eliminating the need to use keystone correction to compensate for image quality.

I. Lens Specifications

The above specifications are governed by the manufacturer's official specifications. For mechanical dimensions, flange distance, and mount type not shown in the specifications table, please contact us with your projector model before placing an order, as ordering solely because the model numbers are similar risks a fitment failure.

II. 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 (5.46-8.70:1). Each image size corresponds to a range of installation distances, and the lens can focus at any distance within that range when installed.

The values above represent the clear distance from the front surface of the lens to the screen and do not include space behind the projector for cooling and cable connections. The calculations are based on a 16:10 image; actual distances must be verified on site and in accordance with the manufacturer's manual.

Image quality varies at the two ends of the zoom range: at the short-throw end, the image is brighter and the edges are slightly softer; at the long-throw end, the edges are sharper and the image is slightly dimmer. When site conditions allow, use the middle of the range. After installation, first find the sharpest position using the focus ring, then fine-tune the lens shift.

III. Compatible Models (13 Units)

The following table is taken from the official compatibility list. Brightness and resolution have been populated from the model database; values that could not be retrieved are shown as “—” and have not been estimated.

To check whether a model not listed is compatible, send us photos of the projector nameplate and the current lens. Platforms from the same generation often share a mount, but ordering based only on a similar model carries risks that are not worth taking.

Throw Ratio by Model Series

The specified throw ratio differs among the series listed below when the same 121-124108-XX Ultra Long Zoom lens is installed, so use the value for the actual projector series during selection.

IV. Three Checks Before Replacement

• Confirm the projector's imaging chip and resolution. The original lens is designed for a specific panel size. With different panel specifications, the image circle cannot cover the full image, resulting in vignetting or light loss at the edges after installation.
• Calculate the installation distance first. The specified throw ratio of this lens is 5.46-8.70:1. Use the table in Section II to calculate the required distance for your venue. A fixed-focus lens offers no margin, and even a zoom lens requires 10–20 cm of clearance at both ends.
• Check the mount and locking mechanism. The original lens is calibrated to the mount of that projector series, and you must hear the lock engage fully after installation. Skewed images and soft edges are usually caused by incomplete locking, not by a problem with the lens itself.

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