SC381 Projector Lens 1.26–1.95:1 for 3 Viewsonic Business Projector Models

SC381 is a medium-to-long-throw lens for the 0.65/0.66/0.67 panel group (Simeline), with a 1.26–1.95:1 throw ratio and lens shift. It is compatible with 3 projector models across 1 model series. This article presents the lens specifications, installation distances, model compatibility list, and replacement considerations all in one place.

1. Lens Specifications

Lens-shift capability is the key differentiator of this lens. The 110% horizontal and 50% vertical shift ranges allow the projector to be installed off the screen centerline and the image repositioned through lens shift without using keystone correction. Keystone correction comes at a cost—each correction step sacrifices some effective pixels and softens text edges. In professional installations, always use lens shift rather than keystone correction whenever possible; preserving image quality is the bottom line.

2. Calculating Installation Distance from Throw Ratio

The throw ratio is the ratio of the installation distance to the image width. This is a zoom lens (1.26–1.95:1), so each image size corresponds to a range of distances, and the lens can be focused at any point within that range during installation.

These figures represent the clear distance from the front of the lens to the screen and do not include clearance for rear ventilation or cable connections. They are calculated for a 16:10 image; actual values should be confirmed through on-site measurements and the manual.

Image quality differs at the two ends of the zoom range: toward the short-throw end, the image is brighter and the edges are slightly less defined; toward the long-throw end, the edges are sharper and brightness is slightly reduced. Where the venue allows, the middle of the range is recommended. After installation, first find the sharpest setting on the focus ring, then fine-tune the lens shift—adjusting both at once makes it difficult to dial in accurately.

3. Compatible Projector Models (3 Models, Simeline)

The table below is ordered by model production date, from newest to oldest, and lists each model's resolution, brightness, and zoom ratio for the original lens, making it easy to identify the right option for your project.

The zoom ratio is the zoom factor of the model's original standard lens (upper limit ÷ lower limit of the original throw-ratio range), not the zoom range of the lens discussed in this article.

Common Features of These Models

The original standard lenses for these 3 models generally have throw ratios concentrated around 1.5-2.4:1. The 1.26–1.95:1 model discussed here provides an adjusted focal range, allowing different image sizes at the same projection distance—this is the direct reason for replacing the lens. It also retains the full lens-shift capability, so the image can still be aligned after the focal range has been adjusted.

4. Three Checks Before Replacement

• Match the panel and resolution. This model is compatible with a 0.67-inch panel. Projectors with a different panel size or resolution will show some differences in projection performance, so the safest approach is to check the nameplate on the projector before installation.
• Check the interface and locking mechanism. Interfaces are generally compatible across platforms of the same generation, but the position of the locking latch varies between generations. If the image is skewed or the edges are not sharp after installation, the locking mechanism is usually not fully engaged; this is generally not an issue with the lens itself.
• Include lens-shift margin in the installation plan. The shift range provides some installation flexibility, but edge image quality declines at the limits. For actual use, keep operation within 70% of the specified values.

For models not listed here, the safest approach is to send us the projector nameplate and a photo of the original lens for verification—platforms of the same generation often share the same interface, but the risk of ordering solely because the model names are similar is not worth taking.