DeltaOptical IR-Cut 1.25″ filter
If you are involved in astrophotography with CCD or CMOS cameras, you know how significant an impact infrared radiation can have on the final image quality. The DeltaOptical IR-Cut filter was designed precisely to address this problem - it cuts off the unwanted part of the spectrum and noticeably improves both sharpness and star roundness in your photographs.
Why does infrared radiation degrade your images?
The optics of most refractors are corrected for chromatic aberration only within the visible light range. With the exception of premium instruments such as Takahashi telescopes, the infrared portion of the spectrum is practically uncorrected. As a result, radiation at wavelengths above 690 nm reaches the sensor at a different focal point than visible light, causing star bloat and an overall drop in contrast. By cutting off this poorly corrected infrared component, you achieve a significant improvement in star sharpness and roundness - something especially appreciated by photographers working with astrographs and mid-range apochromatic refractors.
Key optical properties
- Blocks radiation at wavelengths λ > 690 nm - everything above the visible spectrum boundary
- Fully preserves the hydrogen H-alpha emission line (λ = 656 nm), which is essential for photographing emission nebulae
- Maximum transmission of 95% in the visible light range - no significant signal loss
- Does not block UV radiation - if UV blocking is also required, a separate UV filter should be added
Build quality and compatibility
The filter body is machined from anodized aluminum. The solid and precise construction ensures long service life and reliable seating in a standard 1.25″ eyepiece barrel. The filter threads in easily and fits any standard 1.25″ focuser or camera nose piece.
Who is this filter for?
The DeltaOptical IR-Cut 1.25″ filter is primarily intended for astrophotography with CCD and CMOS cameras. The manufacturer also recommends it as supplementary protection during solar observations - always in combination with a certified solar filter.
This filter is particularly well suited for:
- Photographers working with refractors that lack full APO correction into the infrared range and want to get the most out of their existing optics
- Those photographing emission nebulae who need to preserve the intensity of the H-alpha line while suppressing infrared noise
- Anyone looking for a simple, drop-in addition to their existing 1.25″ accessory set
About DeltaOptical
DeltaOptical is a brand created in collaboration with astronomers and night sky enthusiasts, with the goal of delivering quality optical accessories focused on practical performance and reliability. The extensive product range includes filters, eyepiece accessories, and add-ons for both visual and photographic observation - all designed with the real needs of astronomers in the field and under the starry sky in mind.
Specifications
| Parameter |
Value |
| Barrel size |
1.25″ |
| Cut-off wavelength |
λ > 690 nm |
| H-alpha line transmission (λ = 656 nm) |
Yes - fully preserved |
| Visible light transmission |
up to 95% |
| UV blocking |
No |
| Filter body material |
Anodized aluminum |
| Primary application |
CCD and CMOS astrophotography |
