The ZWO UV/IR-Cut Filter helps keep unwanted ultraviolet and infrared light out of your astronomical images while retaining the visible-light signal. It is intended for imaging setups that need separate UV/IR blocking, particularly colour cameras fitted with an AR-coated protective window rather than an integral UV/IR-cut window.
Camera sensors can record infrared light that your optics do not bring to the same focus as visible light. Blocking that contribution can help improve image sharpness. Choose between 1.25" and 2" mounted formats to suit your filter holder and imaging train.
Choose the right size
| Version | Manufacturer model | Mounting details |
|---|---|---|
| 1.25" | ZWO IRCUT1.25 | Mounted 1.25" filter cell; ZWO specifies 1.85 mm filter thickness |
| 2" | ZWO IRCUT2 | M48 × 0.75 male filter thread; ZWO specifies a 5 mm cell plus 2 mm thread |
The quoted 1.25" filter thickness and 2" cell dimensions describe different aspects of the products; do not treat them as equivalent optical glass thicknesses.
Check your camera and filter holder
- Check whether your camera already has UV/IR blocking built into its protective window before adding another filter.
- Match the mounted filter size to your nosepiece, filter wheel or drawer. Check thread compatibility and clearance, rather than relying on barrel diameter alone.
- Consider the sensor size, focal ratio and distance from the sensor when choosing a filter aperture; a smaller filter can restrict the illuminated field in some configurations.
- Refocus and check your spacing after changing the optical elements in an imaging train.
What this filter does
This is a UV/IR-cut imaging filter. It is not an infrared-pass filter for infrared-only imaging, and it is not a narrowband or dedicated light-pollution filter.
Supplied item
One mounted ZWO UV/IR-cut filter in the size selected. ZWO specifies a protective plastic case for the 1.25" version. Cameras, nosepieces, drawers and filter wheels are sold separately.
Frequently asked questions
Which size should I buy?
Choose the format supported by your filter holder, then check that its aperture is suitable for your sensor and optical arrangement. A 2" filter is not a direct fit in a 1.25" holder.
Will it improve every camera setup?
The benefit depends on whether unwanted UV/IR light is reaching the sensor and how the optics focus it. An additional filter may be unnecessary if the camera already provides appropriate blocking.
Can I use it as a solar filter?
No. This filter does not make a telescope safe for observing or imaging the Sun.
Explore more ZWO cameras and accessories at Dark Clear Skies, or contact us with your camera and filter-holder details for help selecting the format.