EIKI AH-AC24020 Zoom Long-Throw Lens for EK-831DU EK-831U EK-833DU EK-836DU

Eiki Genuine Lens AH-AC24020 Zoom is an original optical accessory for Eiki professional projectors. It is a long-throw lens (Long Throw) with a 2.37-3.60:1 throw ratio. The manufacturer's compatibility list covers 4 models. Before installation, simply verify the projector model and panel size—there is no need to make do with adapter rings. The value of an original lens lies not in the extra figures in the specification sheet, but in its factory calibration to the optical path and mount of that projector series: once installed, the image circle, edge illumination, and focus travel all meet the design specifications, with no need to use keystone correction to compensate for image quality.

I. 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 contact us with the projector model. Placing an order solely because the model looks similar risks a lens that will not fit.

II. Calculating Installation Distance from Throw Ratio

A throw ratio is the ratio of the installation distance to the image width. This original lens is a zoom lens (2.37-3.60:1), so a given image size corresponds to a range of installation distances, and the lens can focus at any position within that range.

These figures represent the clear distance from the front of the lens to the screen and do not account for space behind the projector for heat dissipation and cable connections. They are calculated for a 16:10 image aspect ratio; actual values should be confirmed through on-site measurement and the original manufacturer's manual.

Image quality varies at the two ends of the zoom range: near the short-throw end, the image is brighter and the edges are slightly softer; near the long-throw end, the edges are sharper but brightness is slightly lower. When the venue permits, target the middle of the range. After installation, find the sharpest setting on the focus ring first, then fine-tune the lens shift.

III. Compatible Models (4 Projectors)

The following table comes from the manufacturer's compatibility list. Brightness and resolution are populated from the model database; values that cannot be obtained are shown as “—” and are not estimated.

For a model not on the list, please send us photos of the projector nameplate and the existing lens so we can verify whether it is compatible. Projector platforms of the same generation often share a mount, but the risk of ordering based on a similar model is not worth taking.

Throw Ratios by Model Series

The rated throw ratio differs among the series below when the same AH-AC24020 Zoom lens is installed. Select the value based on the series of the projector you actually have.

IV. Three Checks Before Replacement

• Confirm the projector chip and resolution. The original lens is designed for a specific panel size. With a different panel specification, the image circle cannot cover the full image, causing vignetting or edge light loss after installation.
• Calculate the installation distance first. This lens has a rated throw ratio of 2.37-3.60:1. Use the table in Section II to calculate the distance for your venue. A fixed-focus lens offers no adjustment margin, and even a zoom lens should have 10–20 cm of extra room at both ends.
• Verify 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. A skewed image or soft edges are usually caused by an incompletely engaged lock, not by a problem with the lens itself.

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