Vivitek 3797858100-SB Long Zoom 2 Lens Guide: DU9000, DU9800Z-BK

Vivitek Original Lens 3797858100-SB Long Zoom 2 is an original optical accessory for Vivitek engineering projectors. It is a Long Throw lens with a 4.00-7.00:1 throw ratio for inch panels in the DU/DW/DX engineering series. The factory compatibility list covers 2 models. Before installation, verify the projector model and panel size; there is no need to improvise with adapter rings. The value of an original 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 mount of that projector series. Once installed, the image circle, edge illumination, and focus travel all match the design values, with no need to use keystone correction to compensate for image quality.

1. Lens Specifications

Brand	Vivitek (Vivitek)
Lens Model	3797858100-SB Long Zoom 2
Throw Ratio	4.00-7.00:1
Product Type	Long Throw
Applicable Panels	DU/DW/DX engineering-series inch panels
Compatible Models	2 models
Warranty	12 months; for damage not caused by human error, after-sales service applies, based on the date on the shipping documents

The above specifications are subject to the manufacturer's official specifications. For mechanical dimensions, flange distance, and mount type not shown in the specifications table, please verify them with us using the projector model. Ordering solely on the basis of a similar model carries the risk that the lens will not fit.

2. Calculating Installation Distance from Throw Ratio

The throw ratio is the ratio of the installation distance to the image width. This original lens is a zoom lens (4.00-7.00:1), so each image size corresponds to a range of installation distances. The lens can focus at any position within that range.

Image Size	Image Width	Required Installation Distance
100 inches	2.15 m	approx. 8.60 – 15.05 m
120 inches	2.58 m	approx. 10.32 – 18.06 m
150 inches	3.22 m	approx. 12.90 – 22.57 m
200 inches	4.30 m	approx. 17.20 – 30.10 m

These figures represent the clear distance from the front surface of the lens to the screen and do not include space at the rear of the projector for ventilation and cable connections. The calculations are based on a 16:10 image; actual distances should be confirmed through on-site measurements and the manufacturer's manual.

Image quality differs at the two zoom extremes: near the short end, the image is brighter and the edges are slightly softer; near the long end, the edges are sharper and brightness is slightly reduced. Where the venue allows, a position near the middle of the range is recommended. After installation, find the sharpest setting using the focus ring, then fine-tune the lens shift.

3. Compatible Models (2 Models)

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

Model	Brightness	Resolution
DU9000	12000 lumens	1920x1200
DU9800Z-BK	18000 lumens	1920x1200

For a model not on the list, send us photos of the projector nameplate and the existing lens so we can verify compatibility. Platforms of the same generation often share the same mount, but the risks of ordering based on a similar model are not worth taking.

Throw Ratio by Projector Series

The nominal throw ratio differs by series when the same 3797858100-SB Long Zoom 2 is installed on the models below, so use the value for the series of the actual projector when selecting a lens.

Model Series	Throw Ratio
—	4.00-7.00:1

4. Three Checks Before Replacement

• Make sure the panel size matches. 3797858100-SB Long Zoom 2 is designed for DU/DW/DX engineering-series inch panels. On a projector with a different panel size or resolution, the image circle and edge illumination may be affected even if the lens fits the mount.
• Calculate the installation distance first. This lens has a rated throw ratio of 4.00-7.00:1. Use the table in Section 2 to match the lens to your venue dimensions. A fixed-focus lens offers no adjustment margin, and even a zoom lens requires a 10–20 cm margin at both ends of the range.
• Verify the mount and locking mechanism. The original lens is calibrated to the mount used on that projector series, and you must hear it lock into place after installation. A skewed image or soft edges are usually caused by incomplete locking rather than a problem with 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 actual equipment is the most reliable approach.