ZWO 1.25" UV/IR Cut Filter

Product Overview

The ZWO 1.25" UV/IR Cut Filter is a simple but important imaging accessory for colour astronomy cameras, especially cameras with an AR protect window rather than a built-in UV/IR blocking window. It blocks ultraviolet and infrared light from reaching the camera sensor, helping produce sharper, cleaner visible-light images.

Silicon camera sensors are sensitive beyond the visible spectrum, including infrared. Since most telescope optics are not designed to bring infrared light to the same focus as visible light, unwanted IR can soften stars and reduce image sharpness. A UV/IR cut filter helps keep the recorded image focused on the visible spectrum.

Who Is This Product Best For?

This filter is best for astrophotographers using colour CMOS or CCD cameras that need UV/IR blocking for sharper broadband imaging. It is especially useful with ZWO colour cameras that have an AR protect window instead of an integrated IR-cut window.

Why Choose This Product?

• Sharper colour-camera images: Blocks out-of-focus infrared light that can soften stars and fine detail.
• Protects downstream filters: ZWO notes it can help protect expensive H-alpha filters from infrared radiation during solar-related setups.
• 1.25" threaded format: Fits common 1.25" astronomy filter holders, filter wheels, and accessory threads.
• Protective case included: The vendor lists a protective plastic case with the filter.

Recommended Uses

• Broadband colour astrophotography
• Planetary imaging with colour cameras
• Lunar imaging
• Visible-light imaging through telescopes that do not focus IR cleanly
• Colour cameras with AR protect windows

Compatibility and Accessory Notes

This listing is for the 1.25" ZWO UV/IR Cut Filter. ZWO also offers a 2" version as a separate size. The 1.25" version is suitable for common 1.25" filter cells, filter wheels, and imaging accessories where the optical path accepts 1.25" mounted filters.

Important Limitations

• Not a narrowband filter: This is a UV/IR blocking filter, not an H-alpha, OIII, SII, or light-pollution filter.
• Use the correct size: Choose the 1.25" or 2" version based on your camera, filter wheel, filter drawer, and optical train.
• Not needed for every camera: Some cameras already include UV/IR blocking glass. Check your camera window before adding another filter.

Frequently Asked Questions

What does this filter block?

It blocks ultraviolet and infrared light so the camera records primarily the visible spectrum.

Why do colour astronomy cameras need a UV/IR cut filter?

Many sensors are sensitive to infrared light. If that infrared light reaches the sensor, stars and fine detail can appear softer because the telescope may not focus IR at the same point as visible light.

Does it come with a case?

Yes. ZWO lists a protective plastic case with the 1.25" filter.

Our Recommendation

Ontario Telescope recommends the ZWO 1.25" UV/IR Cut Filter for colour-camera imaging setups that need clean visible-light capture and sharper star profiles. It is a small accessory that can make a noticeable difference when your camera or optical train does not already include effective UV/IR blocking.