Astronomik ASLRGB2 - LRGB Filter set, 2"

A filter set especially designed for astrophotography with CCD and CMOS cameras. These filters provide a natural color reproduction of planets, stars, emission and reflection nebulae.

The transmission properties of the L-RGB Typ 2c filters are optimized for CCD and CMOS astrophotography. The set allows to take images in correct colour for all types of objects. Where other brands make strange compromises, Astronomik does the best colour reproduction possible. Both, stars as well as objects that emit only in spectral lines, are reproduced in their true colors. You get images with perfect colors, as if the objects where bright enough to be seen with photopic vision. This feature is the main difference between Astronomik LRGB filters an those of other manufacturers.

The following aspects have been most important for the design of Astronomik LRGB filters:

♦ simple image processing for the user

♦ highest transmission (nearly 100%) for short exposure times

♦ adjusted transmissions of the individual filters for optimal colour reproduction

♦ integrated IR blocking up to approx. 1150 nm

♦ the use of industry standards

Astronomik doesn´t stop thinking at the step of taking the picture. More important a tool should be given to the astrophotographers that offers a simple and elegant editing process. To maintain the colour, they calculated their filterset for the sRGB color space, that is used as an industry standard from most manufacturers of monitors, printers and imaging software. As a user you do not need to spend time to learn about colourimetry and colour spaces. Astronomik have solved the special problems of astrophotography for you.

Due to the high-precision machining of the carrier substrate, Astronomik filters are parfocal with wedge errors below all usual margins. In order not to be the bottleneck in a high-quality optical system, Astronomik filters are of course diffraction limited. Issues concerning focal distances as well as the exact location of the images of each colour image are not a problem at all!

Main use:

The L-RGB filter set divides the spectrum into its components red, green, blue and luminance. Thus colour separation can be achieved with pure b/w CCD and CMOS sensors. The separation corresponds to the colour sensitivity of the human eye according to DIN 5032. By using the sRGB color space, it is possible to maintain the color of the image throughout the entire image processing and output. With an Astronomik L-RGB filter set and your camera, you create ideal raw material for imageprocessing in the sRGB color space.

Other uses:

♦ In combination with the Astronomik line filters, your images will show interesting details of astronomical objects. For example, the red image can be enhanced by H-alpha or the green image by [O III].
♦ For planetary observation and photography, the color filters are gladly "misused".

Suitability:

♦ Visual observation (dark skies): Good, used as colour filter for planetary observations
♦ Visual observation (urban skies): Good, used as colour filter for planetary observations
♦ Film photography: Unsuitable
♦ CCD and CMOS photography: Very good, excellent colour separation with RGB and L-RGB pics
♦ DSLR photography (original): Unsuitable
♦ DSLR photography (astro modified): Unsuitable
♦ DSLR photography (MC modified): Unsuitable
♦ Webcam / Video (Planets): Good, used as colour filter for imaging planets
♦ Webcam / Video (Deep Sky): Good, used as colour filter for imaging planets

Technical Data:

♦ Parfocal with other Astronomik filters
♦ Glass thickness: 1 mm
♦ Completely resistant against high humidity, scratches and aging effects
♦ Diffraction limited, the filter will not reduce the optical performance of your telescope!
♦ Astronomik filters are delivered in a high-quality, long lasting, filter box

Filter transmission curve:




♦ The horizontal axis is the wavelength in nanometers (nm). 400 nm is deep blue, at 520 nm the human eye senses green and at 600 nm red. At 656 nm is the famous "H-Alpha" emission line of hydrogen.
♦ The transmission in % is plotted on the vertical axis.
♦ The red line shows the transmission of the filter.
♦ Visual filters: The grey line in the background shows the relative sensitivity of the human eye at night. The maximum is at ~510 nm and drops to longer and shorter wavelengths. You can easily see, that you can´t see anything of the H-alpha line at night (even if you can during daylight!) The sensitivity at 656 nm is 0% at night!
♦ Photographic filters: The grey line in the background shows the sensitivity of a typical astro camera sensor.
♦ The most important artifical emission lines are shown in orange. The artifical light pollution is dominated by see mercury (Hg) and sodium (Na), which are used in nearly all streetlights.
♦ The most important emission lines from nebulas are shown in green. The most important lines are from ionized hydrogen (H-alpha and H-beta) and double ionized oyxgen ([O III]). The square brackets indicate that these lines are forbidden.

♦ 4 Filters in plastic boxes