Explore lunar and planetary detail in near-infrared
The Optolong IR Pass 685 nm filter in a 1.25-inch mounted cell is designed for lunar and planetary imaging with an infrared-sensitive camera. It passes near-infrared light while suppressing shorter visible wavelengths, helping you capture an IR image or a luminance layer for an IR-RGB composite.
Why use an IR-pass filter?
Longer wavelengths can be less affected by atmospheric seeing. Optolong designed the IR685 for imaging detail on the Moon and planets, including use as the luminance component of an IR-LRGB workflow. The benefit depends on the target, seeing conditions and the camera's sensitivity in this wavelength range.
- Lunar and planetary imaging: capture near-infrared detail on bright Solar System targets.
- IR-RGB workflow: combine a separately captured IR image with RGB data when that approach suits your processing.
- 1.25-inch mounted format: supplied in a filter cell for compatible 1.25-inch filter holders.
- Protective storage: supplied with a protective plastic case and EVA lining.
What does 685 nm mean?
685 nm identifies the filter's nominal transition region. This is a long-pass imaging filter, rather than a narrowband filter with a 685 nm bandwidth. Optolong describes it as suppressing wavelengths below approximately 670 nm, with transmission rising into the near-infrared.
Manufacturer reference transmission curve, provided as a guide rather than an individual test certificate.
Camera and filter-holder compatibility
Your camera and optical path must transmit near-infrared light. Check the camera's spectral response and sensor-window specification. A UV/IR-cut filter or IR-blocking camera window will suppress the light this filter is intended to pass.
Check that your filter wheel, drawer or camera nosepiece accepts mounted 1.25-inch filters and has sufficient clearance. Refocus after fitting the filter and take a short test sequence before committing to a longer capture.
Specifications
| Brand | Optolong |
|---|---|
| Model | IR Pass 685 nm / IR685 |
| Supplied size | 1.25-inch mounted |
| Filter type | Near-infrared long-pass imaging filter |
| Nominal transition designation | 685 nm |
| Main applications | Lunar and planetary imaging; IR-LRGB luminance capture |
| Camera requirement | Near-infrared sensitivity with a suitable optical path |
What's included
- One Optolong IR Pass 685 nm filter in a 1.25-inch mounting cell.
- Protective plastic case with EVA lining.
For imaging. Not a solar filter. Do not use this filter to observe or photograph the Sun.
Browse the Optolong filter range at Dark Clear Skies or consult Optolong's IR Pass 685 product information.
