What is the primary use of the Antlia IR Pass 850nm filter?
Antlia highly recommends the IR Pass 850nm filter for planetary photography. It passes only infrared light with wavelengths longer than 850nm, where atmospheric seeing has much lower impact on sharpness, resulting in the sharpest and highest contrast planetary image possible.
How does the Antlia 850nm filter help when imaging Jupiter on a night of poor seeing?
Turbulent air blurs fine detail in Jupiter's cloud belts. At wavelengths longer than 850nm, planetary images are less disturbed by wavefront distortions in the atmosphere, so the filter gives a sharper, higher-contrast image than visible light on the same night. Combined with RGB and U-Venus data, this IR luminance image significantly enhances overall image sharpness.
Can I use the Antlia IR Pass 850nm filter for visual observing?
No. At these longer wavelengths the sensitivity of the unaided eye is reduced, so it is not suitable for visual observation. It is a filter for planetary photography with a camera that is sensitive to infrared light. Never look at the Sun with Antlia filters, as serious eye damage will result.
Why is the Antlia IR Pass 850nm filter useful for imaging planets during the day?
The filter makes it possible to image planets during daylight thanks to the dark background sky it creates. The daytime sky is bright mainly because the atmosphere scatters the shorter (blue) wavelengths of sunlight; by passing only light beyond 850nm, the filter darkens that background so the planet stands out.
What's the benefit of using the Antlia 850nm filter to create a luminance channel for Saturn with a monochrome camera?
Combine a luminance image taken with the IR pass filter with RGB and U-Venus filters: overall image sharpness is significantly enhanced and details of planets in different bands are captured. Because seeing has much lower impact beyond 850nm, the IR luminance defines the fine detail in Saturn's rings and cloud bands, while the RGB data provides the color.
Is the Antlia 850nm filter parfocal with other filters?
The substrate thickness is 2mm +/-0.05mm, but parfocality is not specified for this filter. Filters of the same thickness usually need less refocusing when you switch between them, but check focus after each filter change.
