Astronomik L3 UV+IR Blocking Luminance Filter

Astronomik L3 UV+IR Blocking Luminance Filter

  (2 Reviews)
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About this product

Model:  ak_uv-ir_l-3_125
Part Number:  10163125

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

The Luminance channel is probably the most important for a great final image! You want as much signal as possible so the filter should have the highest transmission possible with a wide spectral bandpass. This combination provides the greatest sensitivity and gives you the highest photon counts on your pixels.

While the high transmission level is a great aspect of the new Astronomik Luminance filters, not all optical instruments or additional optical elements like correctors, field-flatteners or reducers, have perfect colour correction so it can be the width of the spectral band pass of  the Luminance filter that can cause problems.

A band pass that is too wide will allow the transmission of incompletely focused light (Chromatic aberration), making stars appear soft or bloated. 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.

L1, L2 or L3?

If you use an optical system that is completely free of any chromatic aberration you should get an L1 filter for your setup. 

For general use the L2 filter is well suited to most optical systems with a corrector, flattener or reducer in the optical train. 

The L3 filter is designed for users of refractors with a less-than-perfect colour correction and in combination with the new Deep-Sky RGB filters, the L3 filter will minimise the problem of bluish halos around stars.


  • Free of halos and reflections
  • Not sensitive to high humidity or ageing effects
  • Scratch-resistant!
  • Excellent quality substrate, diffraction limited - the optical performance of your telescope will not be reduced
  • Parfocal with other Astronomik filters
  • 1mm Glass Thickness
  • Supplied in a high-quality, long lasting, filter box

Additional note for observers working under light polluted skies:
If your observing site suffers from light pollution you should try to use our CLS-CCD as a replacement for the Luminance filter. The transmission curve of the CLS-CCD will give you approximately the same amount of energy in all three colour channels while blocking nearly all unwanted arifical light pollution. Customers who replaced the Lx filter with the CLS-CCD are amazed by the increased quality of their data. This small change gives you the opportunity to take much deeper images from your current observing site.

Transmission Chart


Customer reviews

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Game changing filter
03 June 2022  | 

I bought this filter to combat my CA issue with my sw 72ed. I was recommended this filter on sgl and it hadn't disappointed at all. I needed an ir uv cut filter for my 294mc pro and had issues with CA and star bloat on my zwo ir uv cut filter. So this L3 filter being the strongest at blocking the offending CA and really tightening up the stars is perfect for my scope. I'm really pleased I bought it and worth the expense in my opinion.

Rating (max 5):  
Before and after
04 March 2022  | 

I am using this filter with a 130EDT refractor. Before - the Trapezium stars were a single merged blob. After - the individual stars recorded are much tighter and separate. That is the effect the filter is supposed to have.


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