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Astronomik L-3 UV-IR Blocking Filter - 27 mm Round - L3-27

SKU: ASF-L3-27

Astronomik UV-IR Blocking Luminance Filters

For an exceptional final image, the Luminance channel is probably the most crucial. The filter should feature the highest possible transmission with a wide spectral bandpass so you get as much signal as is viable. This combination enables impressive sensitivity and provides you with the greatest pixel photon counts. While the high transmission level is an excellent feature of Astronomik's new Luminance filters, not all optical instruments, or supplemental optical devices such as correctors, field flatteners, or reducers, enjoy perfect color correction. Thus the Luminance filter's spectral bandpass width can be an issue. A band pass with too much width enables the transmission of light that is not completely focused (chromatic aberration), making stars display as soft or bloated. In such instances image processing can be challenging. Therefore, having a marginally narrower spectral window in your Luminance filter can lessen or even do away with this detrimental effect altogether.

In order to provide users with all the necessary tools to gather the best possible data, Astronomik has bolstered their Luminance filter line. Now you can choose Luminance filter ideally suited for your telescope type to achieve the highest signal and sharpest image for the Luminance channel.

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.

If your optical system is completely chromatic aberration free, you should get an L1 filter for your setup. For general use with most optical systems employing a corrector, flattener or reducer in the optical train, the L2 is optimal. The L3 filter is made for users with refractors that have less than ideal color correction. Plus, when used in conjunction with Astronomik's new Deep-Sky RGB filters, the L3 filter will reduce that annoying bluish halo 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 all available Astronomik filters
  • Provides full protection from the effects of scratching, aging, and high humidity
  • Diffraction limited for no compromise in your telescope system's optical performance!
  • Astronomik filters come with a long-lasting, superior quality plastic storage container