The luminance is very important for the success of Astro Photo! Sharpness, contrast and low noise of the luminance data is vital in order to achieve the best quality in the final result can!
Role of L-filter is to have the maximum transmission over the entire visible spectrum is, because the combination of the broadest possible passage and high transmission makes it possible to collect the largest possible number Photo.
Not all telescopes or additional elements such as correctors, field flattener and Shapley lenses have a perfect color correction. A to broadband L-filter allows wavelengths to pass, for your appearance is not corrected properly. The result is unsightly bloated, blurred stars that do not match the RGB color channels.
Astronomik presents three different UV + IR blocking filter for the luminance channel, they will be denoted by L-1, L-2 and L-third Please pay attention to the corresponding designation in the product name.
To find the right luminance filter: Depending on the color correction of the instruments used the L-filter with the largest passage should be used. The L-1 filter has by far the largest spectral passage, whereas the L-3 filter has the narrowest spectral window. If your used optics can be classified as free from chromatic aberration, the L-1 filter is the right choice. For general use, eg. As in telescopes of different color purity or the use of additional, refractive elements in the beam path, we recommend the Astronomik L-2 version. For a "colorfully" optics, eg an achromatic lens, we recommend the Astronomik L-3 filter to increase image sharpness.
The transmission characteristics and the coating technology of the new Astronomik L-series has been designed so that no halos or reflections are visible. Even with bright stars in the field of nebulae and galaxies with extremely fine structures and high contrast can be displayed.
Like all filters made by Astronomik, the L-1, L-2 and L-3 filters have an extremely resistant and durable coating, applied to a fine special optical substrate as it is also used in the aerospace industry. Prerequisite for such material is streaking, voltage and absence of bubbles. Furthermore, the Astronomik filter carriers are processed in a separate operation in the same thickness: Perfect Homofokalität and lowest wedge errors are the resulting benefits!
Tip: Instead of a luminance to Astronomik CLS-CCD filter! You get a low signal, without the lines of sodium and mercury lamps with much less background noise.