Ricoh 308938 Zoom #4 Long-Throw Lens for PJ WU6181N, PJ WX6181N, PJ X6180N

Ricoh Genuine Lens 308938 Zoom #4 is an original optical accessory for Ricoh engineering projectors. It is a long-throw (Long Throw) lens with a 4.70-7.20:1 throw ratio. The official compatibility list covers 3 projector models; before installation, simply verify the projector model and panel size—there is no need to improvise with adapter rings. The value of a genuine lens lies not in the additional figures on a specification sheet, but in the fact that it is factory-calibrated for the optical path and lens mount of that projector series. Once fitted, the image circle, edge illumination, and focusing travel are all delivered at their designed values, with no need to use keystone correction to compensate for image quality.

I. Lens Specifications

The above specifications are subject to the manufacturer's official specifications. For mechanical dimensions, flange distance, and lens mount type not shown in the table, please provide your projector model when contacting us. Ordering directly based on a similar model carries the risk that the lens will not fit.

II. Converting Throw Ratio to Installation Distance

The throw ratio is the ratio of the installation distance to the image width. This genuine lens is a zoom lens (4.70-7.20:1), so each image size corresponds to a range of installation distances. Focus can be achieved at any distance within that range.

These figures represent the clear distance from the front surface of the lens to the screen and do not include space for rear projector ventilation and cable connections. They are calculated for a 16:10 image aspect ratio; actual distances should be verified on site and against the manufacturer's manual.

Image quality differs at the two ends of the zoom range: the image is brighter with slightly softer edges near the short-throw end, while edges appear sharper and brightness decreases slightly near the long-throw end. Where the venue allows, the middle of the range is recommended. After installation, first find the sharpest position using the focus ring, and then fine-tune the lens shift.

III. Compatible Models (3 Projectors)

The table below is taken from the official compatibility list. Brightness and resolution are populated from the model database; entries that cannot be verified are marked as «—» and are not estimated.

To verify whether a model outside the list is compatible, send us photos of the projector nameplate and the existing lens. Platforms of the same generation often share the same mount, but ordering on the basis of a similar model introduces unnecessary risk.

Throw Ratios for Different Model Series

The rated throw ratio varies by the series to which the same 308938 Zoom #4 is fitted. Select the value based on the series of your actual projector.

IV. Three Checks Before Replacement

• Confirm the projector chip and resolution. Genuine lenses are designed for a specific panel size. When the panel specification differs, the image circle cannot cover the full panel, resulting in vignetting or light loss at the edges.
• Calculate the installation distance first. This lens has a rated throw ratio of 4.70-7.20:1. Use the table in Section 2 to match it to your venue dimensions. A fixed-focal-length lens offers no adjustment range, and even a zoom lens should be given 10–20 cm of margin at both ends.
• Verify the lens mount and locking mechanism. The genuine lens is calibrated for the mount of that projector series, and you must hear it click into the locked position after installation. Image skewing and soft edges are usually caused by an incompletely locked lens rather than by a fault in the lens itself.

If you are unsure, send us one photo each of the projector nameplate and the lens nameplate. Verification against the physical units is the most reliable approach.