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Antlia IR Pass 685nm Filter - 1.25"
The Antlia IR Pass 685nm filter isolates the infrared spectrum by passing only light with wavelengths longer than 685nm, where atmospheric turbulence (seeing) has much lower impact on sharpness. Built on a 2mm thick Schott optical substrate, each filter has 2 sides fine-optically polished to ensure accurate 1/4 wavefront, with 30 arcsecond parallelism.
Beat Atmospheric Seeing with Imaging Beyond 685nm
Atmospheric turbulence, or "seeing," has a much greater effect on shorter wavelengths of light. By passing only light beyond 685nm, this filter records planets with less disturbance from wavefront distortions in the atmosphere, which gives the sharpest and highest contrast image possible on planets such as Jupiter, Mars and Saturn.
1/4 Wavefront Accuracy and 30 Arcsecond Parallelism
A filter is a critical component in your imaging train, and the Antlia 685nm IR Pass is built to high optical standards. Both sides of the Schott substrate are fine-optically polished to ensure accurate 1/4 wavefront, and the two surfaces are parallel to within 30 arcseconds.
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Schott Substrate: Antlia uses a Schott optical substrate, 2mm +/-0.05mm thick.
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Ultra-Thin Filter Cell: The black-anodized, laser-engraved 1.25" (M28.5x0.6) cell is ultra-thin to minimize vignetting by maximizing the clear aperture.
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Surface Quality: 60/40, per MIL-O-13830.
Daylight Imaging and the 685nm Luminance Advantage
Beyond its primary role in reducing seeing, the 685nm IR Pass filter enables advanced imaging techniques. The dark background sky it creates makes it possible to image planets during daylight. It also works well as a luminance channel: combining a luminance image taken with the IR-Pass filter with images taken through RGB and U-Venus filters enhances overall image sharpness and records planetary detail in different bands.
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Why can't I use the Antlia IR Pass 685nm filter for visual observing?
At wavelengths beyond 685nm the sensitivity of the unaided eye is reduced, so the filter is not suitable for visual observation. It is designed for planetary photography.
How does the Antlia 685nm filter help with imaging Jupiter on a turbulent night?
Atmospheric seeing has much lower impact on sharpness at long wavelengths. By passing only light beyond 685nm, the filter records Jupiter with less disturbance from wavefront distortions in the atmosphere, which helps the sharpness and contrast of its cloud bands.
Can I use the Antlia 685nm filter to image planets during the day?
Yes. The filter makes it possible to image planets during daylight because of the dark background sky it creates. DO NOT LOOK AT THE SUN WITH ANTLIA FILTERS.
What is the benefit of using the Antlia 685nm filter as a luminance layer?
Combine a luminance image taken with the IR-Pass filter with images taken through RGB and U-Venus filters. The IR luminance is less affected by seeing and enhances overall image sharpness, while the other filters record planetary detail in different bands.
Is the Antlia IR Pass 685nm filter suitable for deep-sky imaging?
Antlia presents this filter for planetary photography and does not describe deep-sky use. Most nebulae emit their strongest lines in the visible spectrum, which this filter blocks below 685nm. It is not for solar observing or imaging.
Can I use the Antlia IR Pass 685nm filter for solar observing?
No. Antlia does not recommend this filter for solar observing or imaging. DO NOT LOOK AT THE SUN WITH ANTLIA FILTERS. Serious eye damage will result if you fail to observe this warning.
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| Filter Type |
IR pass planetary filter (absorptive) |
| Passband |
Infrared light with wavelengths of more than 685nm |
| Substrate |
Schott optical substrate |
| Filter Thickness |
2mm +/-0.05mm |
| Wavefront Accuracy |
1/4 wavefront |
| Parallelism |
30 arcsec |
| Surface Quality |
60/40 (refer to MIL-O-13830) |
| Filter Ring |
1.25'' (M28.5x0.6), ultra-thin black anodized cell |
| Primary Use |
Planetary photography |
| Secondary Use |
Daylight imaging of planets |
| Not Recommended For |
Solar observing and imaging, visual observation |
| Filter Size |
1.25" mounted |
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Antlia IR Pass 685nm Filter - 1.25" Mounted
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