Eiki AH-AC23020 Zoom Long-Throw Lens for EK-831DU, EK-831U, EK-833DU, EK-836DU

Eiki OEM Lens AH-AC23020 Zoom is an OEM optical accessory for Eiki engineering projectors. It is a long-throw lens with a 3.53-5.65:1 throw ratio. Eiki’s factory compatibility list covers 4 models; simply verify the projector model and panel size before installation—no need to improvise with adapter rings. The value of an OEM lens lies not in a few additional specification figures, but in factory calibration to the optical path and mount of that projector series: once installed, image circle coverage, edge illumination, and focus travel all meet their design values, with no need to compensate for image quality using keystone correction.

1. Lens Specifications

Brand	Eiki (Eiki)
Lens Model	AH-AC23020 Zoom
Throw Ratio	3.53-5.65:1
Product Type	Long Throw
Compatible Models	4 projector models
Warranty	12 months; damage not caused by the user is eligible for after-sales service, based on the date shown on the shipping documents

These specifications are subject to the manufacturer’s official specifications. For mechanical dimensions, flange distance, and mount type not shown in the specifications table, please contact our team with the projector model. Ordering based solely on a similar model carries the risk that the lens will not fit.

2. Installation Distance from Throw Ratio

The throw ratio is the ratio of the installation distance to the image width. This OEM lens is a zoom lens (3.53-5.65:1), so a given image size corresponds to a range of installation distances; it can focus at any point within that range.

Image Size	Image Width	Required Installation Distance
100 inches	2.15 m	Approx. 7.59 – 12.15 m
120 inches	2.58 m	Approx. 9.11 – 14.58 m
150 inches	3.22 m	Approx. 11.38 – 18.22 m
200 inches	4.30 m	Approx. 15.18 – 24.30 m

These figures represent the clear distance from the front of the lens to the screen and do not include space for rear housing ventilation and cable connections. They are calculated for a 16:10 image; in practice, rely on on-site measurements and the manufacturer’s manual.

Image quality differs at the two ends of the zoom range: toward the close end, the image is brighter and the edges are slightly softer; toward the far end, the edges are sharper and brightness drops slightly. Where the venue allows, use the middle of the range. After installation, first find the position on the focus ring that produces the sharpest image, then fine-tune the lens shift.

3. Compatible Models (4 Models)

The following table is taken from Eiki’s factory compatibility list. Brightness and resolution are populated from the model database; entries that cannot be verified are shown as “—” and are not guessed.

Model	Brightness	Resolution
EIKI EK-831DU	—	—
EIKI EK-831U	—	—
EIKI EK-833DU	—	—
EIKI EK-836DU	—	—

To check compatibility with a model not on the list, send us a photo of the projector nameplate and the current lens. Platforms of the same generation often share a mount, but ordering based on a similar model number is not worth the risk.

Throw Ratios by Projector Series

When the same AH-AC23020 Zoom is installed on the following series, the rated throw ratio varies. Use the value for the series of the actual projector.

Projector Series	Throw Ratio
—	3.53-5.65:1

4. Three Checks Before Replacement

• Confirm the projector chip and resolution. OEM lenses are designed for a specific panel size. If the panel specifications differ, the image circle cannot cover the full image area, resulting in vignetting or light loss at the edges.
• Calculate the installation distance first. This lens has a rated throw ratio of 3.53-5.65:1. Use the table in Section 2 to calculate the distance for your venue. A prime lens offers no adjustment margin, and even a zoom lens requires 10–20 cm of clearance at both ends of the range.
• Verify the mount and locking mechanism. The OEM lens is calibrated for the mount used on that projector series, and you must hear the lock engage after installation. A skewed image or soft edges are usually caused by the lock not being fully engaged, not by the lens itself.

If you are unsure, take one photo of the projector nameplate and one of the current lens nameplate, then send them to us. Verification against the physical products is the most reliable approach.