Vivitek GC805G Ultra Short Fixed Lens Guide: D5280U Compatibility

Vivitek OEM Lens GC805G Ultra Short Fixed is an OEM optical accessory for Vivitek professional projectors. It is a short-throw (Short Throw) lens with a 0.77:1 throw ratio, designed for D/H Engineering·Cinema Series panels measured in inches. The official compatibility list covers 1 projector model; before installation, simply verify the projector model and panel size, with no need for an adapter ring. The value of an OEM lens lies not in the extra figures it adds to a specification sheet, but in the fact that it is calibrated at the factory to the optical path and mount of projectors in that series. Once installed, the image circle, edge illumination, and focusing travel are all at their design values, eliminating the need to compensate for image quality with keystone correction.

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 contact us with the projector model for verification. Placing an order based solely on a similar model carries the risk of the lens not fitting.

II. Calculating the 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 fixed focal length (0.77:1), so the installation distance varies linearly with image size and offers no adjustment margin. Accurate measurements are essential before installation.

The figures above represent the clear distance from the front surface of the lens to the screen and do not include space behind the projector for heat dissipation and cable connections. They are calculated for a 16:10 image aspect ratio; in practice, follow on-site measurements and the original manufacturer's manual.

III. Compatible Models (1 Projector)

The table below is taken from the official compatibility list. Brightness and resolution are populated from the model database; values that cannot be obtained are shown as “—”, with no assumptions made.

For compatibility with a model not on the list, please send us photos of the projector nameplate and existing lens for verification. Projectors of the same generation often share the same mount, but ordering based solely on a similar model carries unnecessary risk.

Throw Ratios for Different Model Series

The rated throw ratio varies by series when the same GC805G Ultra Short Fixed lens is used with the series listed below. Select the value according to the series of the actual projector.

IV. Three Checks Before Replacement

• Make sure the panel size matches. GC805G Ultra Short Fixed is designed for D/H Engineering·Cinema Series (inches) panels. Even if the lens fits the mount, a projector with a different panel size or resolution may experience image circle and edge illumination problems.
• Calculate the installation distance first. This lens has a rated throw ratio of 0.77:1. Use the table in Section II to calculate the distance for your installation site. A fixed-focal-length lens offers no adjustment margin; even a zoom lens requires 10–20 cm of clearance at both ends.
• Verify the mount and locking mechanism. The OEM lens is calibrated to the mount of projectors in this series, and you must hear it lock securely into place after installation. A skewed image or soft edges are usually caused by incomplete locking rather than 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 physical items is the safest approach.