SC391 Projector Lens 1.05–1.59:1 for 3 XGIMI Engineering Projectors Including S90, S80, S70

SC391 is a medium-to-long-throw lens for 0.8-inch panels (XGIMI), with a 1.05–1.59:1 throw ratio and lens shift. It is compatible with 3 models across 1 model series. This article presents the lens specifications, installation distances, model compatibility list, and replacement considerations in one place.

1. Lens Specifications

Lens shift is the key differentiator of this lens. A shift range of ±35.5 horizontal and ±16 vertical allows the projector to be installed off the screen's center axis, with lens shift moving the image back into alignment without the need for keystone correction. Keystone correction comes at a cost—each correction step reduces the effective pixel count and makes text edges appear soft. In professional installations, never use keystone correction when lens shift can solve the alignment issue; preserving image quality is the priority.

2. Calculating Installation Distance from Throw Ratio

The throw ratio is the ratio of installation distance to image width. This lens has a zoom range of 1.05–1.59:1, so each image size corresponds to a range of installation distances, and focus can be achieved anywhere within that range during installation.

The distances above are clear distances from the front of the lens to the screen and do not include space for rear chassis cooling and cable connections. Values are calculated for a 16:10 aspect ratio; actual distances should be verified on site and against the 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 less defined; near the long-throw end, the edges are sharper and brightness is slightly lower. When the venue allows, use the middle of the range. After installation, first find the sharpest position on the focus ring, then fine-tune the lens shift—adjusting both at the same time makes precise alignment difficult.

3. Compatible Models (3 Models, XGIMI)

The table below is ordered from newest to oldest by model production date and includes each model's resolution, brightness, and factory lens zoom ratio, enabling quick identification according to project requirements.

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

Common Features of These Models

The factory standard lenses for these 3 models generally have throw ratios in the 1.2-1.8:1 range. The 1.05–1.59:1 ratio of the model discussed here effectively adjusts the focal range, allowing different image sizes at the same projection distance—this is the direct reason for replacing the lens. It also retains full lens shift capability, allowing the image to remain properly aligned after the focal range is adjusted.

4. Three Checks Before Replacement

• Confirm that the panel and resolution match. This model is compatible with a 0.80-inch panel. Projectors with a different panel size or resolution will show some differences in projection performance, so checking the chassis nameplate before installation is the safest approach.
• Check the interface and locking mechanism. Interfaces are generally compatible across platforms of the same generation, but the position of the locking latch differs between generations. If the image is skewed or the edges are not sharp after installation, the lock is usually not fully engaged; this is not a problem with the lens itself.
• Factor the lens shift margin into the installation. The shift range provides some installation flexibility, but edge image quality declines when the shift is pushed to its limit. For normal use, keep the actual shift within 70% of the specified value.

For models not included in the list, the safest option is to send us the chassis nameplate and a photo of the original lens for verification—platforms of the same generation often share interfaces, but the risk of ordering based solely on a similar model designation is not worth taking.