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Astronomik L-3 UV-IR Blocking Filter - 31 mm Round - L3-31

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SKU: ASF-L3-31

Astronomik UV-IR Blocking Luminance Filters


In order to achieve spectacular final image results, the Luminance channel is probably the most critical element. Therefore the filter being used should feature the highest possible transmission with a wide spectral bandpass in order to gain as much signal as you can. These two factors enable the greatest sensitivity and provide you with the highest photon counts on your pixels. Although the high level of transmission these new Astronomik Luminance filters have is a terrific feature, not all optical instruments (or additional optical elements such as correctors, reducers, and flatteners) can boast ideal color correction. Because of this, a wider spectral band pass can cause problems like the appearance of soft or bloated stars that are the result of insufficiently focused light (chromatic aberration). In such instances, image processing can be a challenge. So having a spectral window that is marginally more narrow can either totally eliminate or at least lessen this damaging effect.

Astronomik has updated their Luminance filter line to include three different spectral window widths so that you can match your L filter to the type of telescope you use. The "L-2" filter is very similar to the classic Astronomik Luminance filter. By contrast, the L-1 has a wider spectral window, while the L-3's spectral window is narrower.

The spectral window width you choose for Luminace data will be determined by the color correction of your telescope. The widest spectral window is offered by the L1, while the L3 provides the most narrow. In the middle is the L2 which is about the same as the current Astronomik L-Filter.

For optical systems that are totally free of chromatic aberration, the L1 filter is the best option. When working with most optical systems using a correcto, flattener, or reducer in the optical train for common use, the L2 is your choice. Lastly, for users with refractors that feature less than perfect color correction, the L3 filter works best. Also, the L3 can combine with Astronomik's new Deep-Sky RGB filters to lessen the bluish halo effect 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 galaxies or nebulae.

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 Astronomik filters are parfocal.

Astronomik UV-IR Blocking Luminance Filter Highlights


  • Parfocal with any available Astronomik filter
  • Offers total resistance to the effects of scratching, aging, and high humidity
  • Diffraction limited, this filter will not compromise the optical efficiency of your telescope system
  • Astronomik filters are delivered with a long-lasting plastic storage container of superior quality