Astronomik L2 UV-IR Block filter (36mm)

The Luminance channel is probably the most important for a great final image! You want as much signal as possible so the filter should have the highest transmission possible with a wide spectral bandpass. This combination provides the greatest sensitivity and gives you the highest photon counts on your pixels. While the high transmission level is a great aspect of the new Astronomik Luminance filters, not all optical instruments or additional optical elements like correctors, field-flatteners or reducers, have perfect colour correction so it can be the width of the spectral band pass of  the Luminance filter that can cause problems. A band pass that is too wide will allow the transmission of incompletely focused light (Chromatic aberration), making stars appear soft or bloated. In such cases image processing can become difficult, so having a slightly narrowed spectral window in your Luminance filter can reduce or eliminate this damaging effect.

To give you all the tools to gather the best data possible : Now you can select a Luminance filter perfectly matched to the kind of telescope you use, to get the highest signal and sharpest image for the Luminance channel! Depending on the color correction of your scope you may use a wider spectral window for the Luminance data. The L1 filter has the widest spectral window, the L2 is about the same as our current L-Filter and the L3 is much narrower. If you use an optical system that is completely free of any chromatic aberration you should get an L1 filter for your setup. For general use the L2 filter is well suited to most optical systems with a corrector, flattener or reducer in the optical train while the L3 filter is designed for users of refractors with a less-than-perfect color correction and in combination with the new Deep-Sky RGB filters, the L3 filter will minimise the problem of bluish halos around stars. The transmission curve characteristics and coatings on the new Luminance filters have been designed and engineered in such a way that no halos or reflections will be visible. Even with bright stars in the field of view you will be able to reveal the faintest structures in nebulas or galaxies. Like all Astronomik Filters, the new Luminance filters are made using an extremely durable and scratch resistant coating, deposited on the finest polished optical substrate, which is free of any striae or internal strains. All substrates are made to exactly the same thickness, so all of our filters are parfocal. If your observing site suffers from light pollution you should try to use our CLS-CCD as a replacement for the Luminance filter. The transmission curve of the CLS-CCD will give you approximately the same amount of energy in all three colour channels while blocking nearly all unwanted artifical light pollution. Customers who replaced the Lx filter with the CLS-CCD are amazed by the increased quality of their data. This small change gives you the opportunity to take much deeper images from your current observing site.we have expanded our line of Luminance filtersAdditional note for observers working under light polluted skies:

The transmission properties of the L-RGB Typ 2c filters are optimized for CCD astrophotography. The set allows to take images in correct colour for all types of objects. Where other brands make strange compromises, we do 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 CCD 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 filters an those of other manufacturers.

The following aspects have been most important for the design of our filterset:
- simple image processing for the user
- highest transmission (nearly 100%) for short exposure times
- adjusted transmissions of the individual filters for optimal colour reproduction
- 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, we calculated our 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. We have solved the special problems of astrophotography for you.

Due to the high-precision machining of the carrier substrate, our 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 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 OIII.
• For planetary observation and photography the color filters are gladly "misused".

Technical Data

• Parfocal with other Astronomik filters
• Glass thickness: 1mm
• 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
• Since 2008 we do ship filters with a completely new design. Any kind of halo or strange reflection is a matter of past