The Antlia LRGBR+ Dark series filters are designed for deep space photography with monochrome cameras. The Dark series has an extended spectral range of 390 - 1000nm, allowing you to take advantage of the high sensitivity in the ultraviolet and near infrared range of modern CMOS cameras.
The LRGB Dark series filters are made of quartz glass which has excellent thermal and mechanical properties due to its ultra-low thermal expansion coefficient. This makes these filters perfect for imaging and research in challenging environmental conditions.
Note: The Dark series can be purchased with just the LRGB filters or with an additional R+ filter which has a transmission of between 700 - 1000nm. Please choose carefully.
Each filter is fully multi-coated to minimise internal reflections, halos around stars and to assure a high transmission which is above 95%. To even further enhance the contrast, reduce the glare and internal reflections, Antlia applies edge-blackening coating on each filter.
The width of bandpass of the 3 RGB filters is balanced with the spectral response of the most common CCD and CMOS cameras. This expedient allows to balance the exposure of each channel with the ratio of 1:1:1. That means the exposure time in red is equal to the exposure time in green and in blue.
During the post-processing, it will be easier to obtain images with a natural colour balance thus without colour dominances. The R and R+ data can be combined to form an enhanced red channel, which can then be combined as you normally would with the other channels.
The LRGB Dark series filters are best paired with the new Antlia 2.5nm & 2.8nm narrowband filters as they share the same quartz substrate and refractive index. This means they are more parfocal and less refocusing may be needed between filters.
|Glass thickness||2.0 mm ±0.05|
|Optical flatness||1/4 λ (wavefront)|
|Coating||Double-sided multilayer nano-coating|
|Surface quality||60/40 (in accordance with US military watch MIL-O-13830)|
|Glass type||Monolithic optical substrate (non glued)|
|Filter size||Mounted 2", Unmounted 36 mm