NEC NP31ZL-4K Zoom Standard Throw Lens for PX1005QL-B, PX1005QL-B-18, PX1005QL-W, PX1005QL-W-18

NEC Original Lens NP31ZL-4K Zoom is an OEM optical accessory for NEC business projectors. It is a standard-throw lens (Standard Throw) with a throw ratio of 0.74-0.93:1. The OEM compatibility list covers 4 models, so you only need to verify the projector model and panel size before installation; there is no need to make do with adapter rings. The value of an OEM lens lies not in the extra figures in the specification sheet, but in the fact that it is calibrated at the factory to the optical path and lens mount of that projector series. Once installed, the image circle, edge illumination, and focusing travel all meet their design values, eliminating the need to compensate for image quality with keystone correction.

1. Lens Specifications

The above specifications are based on the OEM specifications. For mechanical dimensions, flange distance, and lens-mount type not shown in the specification table, please contact us with the projector model for verification. Ordering solely on the basis of a similar model carries the risk of a lens that will not fit.

2. Converting Throw Ratio to Installation Distance

The throw ratio is the ratio of the installation distance to the image width. This OEM lens is a zoom lens (0.74-0.93:1), so a given image size corresponds to a range of installation distances. During installation, focus can be achieved at any distance within that range.

These distances represent the clear distance from the front surface of the lens to the screen and do not include the space required for cooling and cable connections at the rear of the projector. They are calculated for a 16:10 image; the actual distance should be confirmed through on-site measurement and in accordance with the OEM manual.

Image quality varies at the two ends of the zoom range: near the close end, the image is brighter and the edges are slightly softer; near the far end, the edges are sharper and brightness is slightly lower. Where the venue allows, we recommend positioning the lens in the middle of the range. After installation, first find the sharpest setting on the focus ring, then fine-tune the lens shift.

3. Compatible Projector Models (4 Models)

The table below is taken from the OEM compatibility list. Brightness and resolution are populated from the model database; where the data is unavailable, “—” is shown, with no assumptions made.

For compatibility with a model not listed, please send us photos of the projector nameplate and current lens so we can verify it. Platforms from the same generation often share the same lens mount, but the risk of ordering based solely on a similar model is not worth taking.

Throw Ratios by Projector Series

The rated throw ratio of the same NP31ZL-4K Zoom varies by projector series when installed on the series listed below. For model selection, use the value for the series of the projector in use.

4. Three Checks Before Replacement

• Confirm the projector panel and resolution. The OEM lens is designed for a specific panel size. If the panel specifications differ, the image circle cannot cover the full image, resulting in vignetting or light loss at the edges.
• Calculate the installation distance first. This lens has a rated throw ratio of 0.74-0.93:1. Use the table in Section 2 to match the dimensions of your venue. A fixed-focus lens offers no adjustment margin, while a zoom lens should still allow 10–20 cm of margin at both ends.
• Check the lens mount and locking mechanism. The OEM lens is calibrated to the lens mount of that projector series. After installation, you must hear it lock into place. A skewed image or soft edges usually indicate that the lens is not fully locked, rather than a problem with the lens itself.

If you are unsure, send us one photo of the projector nameplate and one of the lens nameplate. Verification against the actual items is the safest approach.