Christie 121-130105-XX Medium Zoom Long-Throw Lens Guide: 15 Compatible Models

Christie Original Lens 121-130105-XX Medium Zoom is an original optical accessory for Christie engineering projectors. It is a long-throw (Long Throw) lens with a throw ratio of 1.70-2.90:1. The factory compatibility list covers 15 projector models. Before installation, simply verify the projector model and panel size; no adapter ring workaround is needed. The value of an original lens lies not in the additional figures in its specification sheet, but in its factory calibration to the optical path and lens mount of the corresponding projector series. Once installed, the image circle, edge illumination, and focusing range all meet the design specifications, eliminating the need to compensate for image quality with keystone correction.

1. Lens Specifications

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

2. Calculating Installation Distance from the Throw Ratio

The throw ratio is the ratio of installation distance to image width. This original lens is a zoom lens (1.70-2.90:1), so a given image size corresponds to a range of installation distances. It can achieve focus anywhere within this range during installation.

The figures above represent the clear distance from the front of the lens to the screen and do not include space for rear housing ventilation and wiring. They are calculated for a 16:10 image; actual values are subject to on-site measurements and the original manufacturer's manual.

Image performance differs at the two ends of the zoom range: images are brighter with slightly softer edges near the short-throw end, while edges are sharper with slightly lower brightness near the long-throw end. Where the venue allows, placing the projector near the middle of the range is recommended. After installation, first find the sharpest setting on the focus ring, then fine-tune the lens shift.

3. Compatible Models (15 Models)

The table below is taken from the factory compatibility list. Brightness and resolution are populated from the model database; unavailable figures are marked as "—", with no estimates made.

To determine whether a model not listed here is compatible, send us photographs of the projector nameplate and the existing lens. Platforms of the same generation often share the same mount, but the risks of ordering solely on the basis of a similar model are not worth taking.

Throw Ratio by Projector Series

The rated throw ratio of the same 121-130105-XX Medium Zoom lens varies by projector series. Use the value for the series of the actual projector when selecting a lens.

4. Three Checks Before Replacement

• Confirm the projector imaging chip and resolution. Original lenses are designed for specific panel sizes. If the panel specifications differ, the image circle cannot cover the panel, resulting in vignetting or edge light loss after installation.
• Calculate the installation distance first. The rated throw ratio of this lens is 1.70-2.90:1. Apply the table in Section 2 to your venue dimensions. Fixed-focus lenses provide no adjustment margin, while even a zoom lens should have 10–20 cm of allowance at both ends of the range.
• Verify the mount and locking mechanism. Original lenses are calibrated to the lens mount of the corresponding projector series. After installation, you must hear the locking mechanism engage. 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 photograph of the projector nameplate and one of the existing lens nameplate, then send them to us. Verification against the physical items is the most reliable approach.