IR850 Filter -Size 1.25-inch - Planetary Filter
Our normal spectral/visual bandwidth is 400 to 700 nm. This absorptive filter highlights bandwidths 850 nm and up to 1050 nm. This beyond deep red is past the edge of visible light and fully in the infrared (ISO = NIR -the infrared subdivision "near infrared"). LED light is virtually non-existent in the range.
At long-wavelength spectral range the atmospheric air turbulence (seeing) has much lower impact on the sharpness. The closer to the infrared band, planetary images are less disturbed by wavefront distortions in the atmosphere (seeing), result in the sharpest and highest contrast image possible. Dark structures on the Moon, Mars, Jupiter, Saturn, Neptune, Uranus, and the Sun become much sharper.
IR filters are best used in planetary/ solar system imaging.
To see the graph, click on the Gallery thumbnail image to expand. Then use [CTRL]-scroll-up for an even closer look.
Note: Never use this filter to view the Sun.
The Antlia Filters Production Process:
In the production process, Antlia Filters uses very strict quality control standards. Each filter is individually tested and scanned to ensure that the product meets the parameters we need. In particular, starting from the selection of the substrate, they must control the tolerance of each substrate to a very high standard of +/-0.05 mm. As we all know, when light passes through optical materials, it will be refracted and the thickness of the glass will affect the length of light refraction. Antlia Filters allows their filters to achieve parfocal by minimizing this tolerance of +/-0.05 mm.
All Antlia Infrared filters edge are blackened. It is critical to minimize stray light for a filter that blocks most light except for the designated bandpass and longer. As edge blackening must be hand-made, it becomes very costly to them.
Their cut-off rate has reached a very high technical data point. Many users will be very concerned about how high the filter transmission rate is and ignore the cut-off rate. It is a very important quality index. They keep the signal of 88%T at the 685 nm line and longer. This makes it stable as the filter becomes spectrally narrower to ensure best Signal-to-noise Ratio, a cut-off rate of OD3 (0.1%) is required to reduce interference from other wavelengths. It is a very important quality index, and the accomplishment is very difficult, This process requires very high-end equipment, constantly thickens the layers of coating, add longer production times, and adds more cost to the completed product.
By combining a luminance image taken with the IR-Pass filter, along with RGB and U-Venus filters, overall image sharpness is significantly enhanced and details of planets in different bands are taken. The filter is also possible to image the other planets during daylight due to the dark background sky created by the 850 nm IR Pass Filter.
- Schott optical substrate.
- 1.25-inch (2 mm+/-0.05 mm).
- Surface Quality: 60/40 (Refer to MIL-O-13830).
- 2 sides fine-optically polished to ensure accurate 1/4 wavefront.
- 30 arcsec parallelism.
- Cut-off Wavelength of Antlia IR850 filter below: 850 nm.
- IR 850 nm T＞88%, (88% transmission at line 850 nm ＞OD3（0.1%）at 850 to 1100 nm).
- 2 sides Multi-layers anti-reflection coating.
- Single / Non-glued substrate.
- Filter Ring: 1.25-inch (M26*0.6 thread). Ultra-thin filter cell to minimize vignetting by maximizing possible clear aperture. Black Anodized Finish.
- Laser Engraving No Fading..
- Size: Mounted; 1.25-inch.