Astronomik L-3 - UV IR block filter 2" (M48)

The luminance channel is most important for a successful astrophoto! Sharpness, contrast and low noise of the luminance data are crucial in order to achieve the best possible quality in the finished result.
 
 blocks UV and IR
 narrow band, good for telescopes with stronger chromatic aberration
 finely optically polished substrate
 homofocal to other astronomy filters

 
Astronomy Luminance L-1, L-2, L-3 filters
The luminance channel is most important for a successful astrophoto! Sharpness, contrast and low noise of the luminance data are crucial in order to achieve the best possible quality in the finished result.

Astronomik offers three UV+IR block filters for the luminance channel. The passbands are selected so that an optimally sharp and high-contrast image can be obtained with all optics and every CCD and CMOS camera.

The task of the L filter is to have the maximum transmission over the entire visible spectrum, because the combination of the widest possible passage and high transmission makes it possible to capture the largest possible number of photos.

Unfortunately, in the "real" world, not all telescopes or additional elements such as correctors, field levelers or Shapley lenses have perfect color correction. An L filter that is too broadband allows wavelengths to pass through for which an optic may not be fully corrected. The result is unsightly bloated, blurry stars that don't match the RGB color channels.

The Astronomik L-1, L-2 and L-3 filters eliminate or reduce the problem.
 
Choosing the right filter
Depending on the color correction of the instruments used, the L filter with the largest sensible transmission should be used. The L-1 filter has by far the largest spectral transmission, whereas the L-3 filter has the narrowest spectral window. The L-2 filter corresponds to a "normal" L filter.

If the optics you use can be classified as "free of color errors", the L-1 filter is the right choice. For general use, e.g. B. on telescopes of different color purity or the use of additional light-refracting elements in the beam path, we recommend the Astronomik L-2 version. For “colorful” optics, we recommend the Astronomik L-3 filter to increase image sharpness.

The transmission properties and coating technology of the Astronomik L series were developed to optimally suppress halos or reflections. Even with bright stars in the field of view, nebulae and galaxies are imaged with the finest structures and highest contrast.

Like all filters from Astronomik, the L-1, L-2 and L-3 filters have an extremely robust and long-lasting coating, applied to a special fine-optical substrate, which is also used in space travel. The basic requirement for such material is freedom from streaks, tension and bubbles. Furthermore, the Astronomik filter carriers are machined to the same thickness in a separate operation: perfect homofocality and the lowest wedge error are the resulting advantages.

An addition for photographers working under light-polluted skies:

Use the Astronomik CLS CCD filter instead of a luminance filter! You get an L signal without the lines of sodium and mercury vapor lamps, with much less background noise. Feedback from highly satisfied customers all over the world confirms the advantages of the CLS CCD filter for the luminance channel and makes color photography of the deep sky possible in some regions!
 
Type: interference filter, bandpass
Maximum transmission: over 95%
Carrier: Finely optically polished glass
Anti-reflective coating: Not sensitive to moisture, not aging, scratch-resistant
Filter thickness: 1mm
Homofocal: with all other astronomical filters
Frame: aluminum