Astronomik L-1, L-2 and L-3 Luminance Filters

Astronomik now offers you a range of three different UV + IR blockers as luminance filters. The different spectral window of each new luminance filter is designed to tune your setup to get the sharpest image from any optical design and any camera.

The importance of the luminance layer

The luminance channel is probably the most important for a nice final image! You want as much signal as possible so that the filter has the highest possible transmission with a wide spectral bandwidth. This combination provides the highest sensitivity and gives you the most photons on your pixels. Although the high level of transmission is an important aspect of the new Astronomik Luminance filters, not all optical instruments or additional optical elements such as correctors, field flatteners or reducers have perfect color correction, which can match the spectral bandwidth of the Luminance Filter which can cause problems. Too wide a bandpass will allow transmission of incompletely focused light (chromatic aberration), making stars appear soft or puffy. 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.


The transmission curve characteristics and coatings of the new luminance filters have been designed and manufactured so that no halos or reflections are visible. Even with bright stars in the field of view, you will be able to reveal the faintest structures in nebulae or galaxies.

Like all Astronomik filters, the new luminance filters are manufactured using an extremely durable, scratch-resistant coating deposited on the finest polished optical substrate, free of ridges or internal stresses. All substrates are exactly the same thickness, so all our filters are parfocal.

Additional note for observers working under lightly polluted skies:

If your observing site suffers from light pollution, you should try using our CLS-CCD as a replacement for the luminance filter. The CLS-CCD's transmission curve will give you approximately the same amount of power in all three color channels while blocking out almost any unwanted artificial light pollution. Customers who have replaced the L filter with the CLS-CCD are surprised by the improved quality of their data. This small change gives you the ability to take much deeper images of your current observing site.