Barco EN51 Standard Zoom Long-Throw Projector Lens: Compatible with CTHD-61B, CTPN-41B, CTWQ-51B

Barco Original Lens EN51 Standard Zoom is a genuine optical accessory for Barco installation projectors, belonging to the long-throw category, with a throw ratio of 1.71-2.37:1. The original compatibility list covers 9 projector models; before installation, simply verify against the projector model and panel size — no adapter rings needed. The value of an original lens isn't a few extra rows of numbers on a spec sheet, but that it is calibrated at the factory to the optical path and bayonet of that projector series: once mounted, the image circle, edge illumination, and focus travel all match design values, so you don't need keystone correction to compensate for image quality.

1. Lens Specifications

The above specifications are subject to the original manufacturer's specifications. For mechanical dimensions, flange focal distance, and bayonet type not shown in the spec table, please verify with us against your projector model — ordering based on model similarity alone carries the risk of incompatibility.

2. Converting Throw Ratio to Installation Distance

Throw ratio is the ratio of installation distance to image width. This original lens is a zoom lens (1.71-2.37:1), so a given image size corresponds to a range of distances; as long as installation falls within this range, focus can be achieved.

The above figures are the clear distance from the lens face to the screen, excluding rear ventilation and cabling space behind the projector body. Calculated for 16:10 aspect ratio; actual values are subject to on-site measurement and the original manufacturer's manual.

Image quality differs at the two ends of the zoom range: toward the near end the image is brighter with slightly softer edges; toward the far end the edges are sharper with slightly reduced brightness. Where space permits, it is recommended to land in the middle of the range; after installation, first find the sharpest position on the focus ring, then fine-tune the shift.

3. Compatible Models (9)

The table below is taken from the original compatibility list; brightness and resolution are filled in from the model database, with "—" where unavailable, without speculation.

To determine whether models outside the list are usable, please send us photos of the projector nameplate and the existing lens for verification — same-generation platforms often share a bayonet, but ordering based on model similarity is a risk not worth taking.

Throw Ratio Across Model Series

The same EN51 Standard Zoom mounted on the following series does not have the same nominal throw ratio; selection should be based on the series of the actual projector.

4. Three Things to Confirm Before Replacement

• Confirm the projector chip and resolution. Original lenses are designed for specific panel sizes; with a different panel specification, the image circle cannot cover it, resulting in vignetting or edge light loss after installation.
• Calculate the installation distance first. This lens has a nominal throw ratio of 1.71-2.37:1; use the table in Section 2 to map it to your venue's dimensions. Prime lenses have no margin, and even with a zoom lens, leave 10–20 cm at both ends.
• Verify the bayonet and locking. Original lenses are calibrated to the bayonet of that projector series; after installation, you must hear it lock into place. A skewed image or soft edges are mostly due to incomplete locking, not a problem with the lens itself.

If unsure, take a photo of the projector nameplate and the existing lens nameplate and send them to us — verification against the actual hardware is the safest approach.