Astronomik L-2 UV-IR Blocker 1.25-Inch Filter

Astronomik 1.25-Inch L-2 Filter UV-IR Blocker for AstroPhotography
Mounted filter in 1.25" cell (M28.5mm x 0.5mm)UV and IR cut Filter for digital photography.

We have re-designed all of our photographic filters. Since the end of 2008 we are shipping our new "Halo-Free" filters.

The Astronomik UV-IR Blocker lets the full range of sensitivity of the human eye (according to DIN 5031) pass, and blocks all other parts of the spectrum in the UV and IR. The Astronomik UV-IR Blocker is the ideal choice as a luminance filter for any kind of digital photography.

Because of the perfect blocking of UV and IR all optical problems in these parts of the spectrum are avoided.

The filter is optimized for systems with focal ratios between f/0.5 and f/50. The typical transmission is higher than 99%.

Main use

The UV-IR Blocker gives you a perfect parfocal filter for the luminance channel. It is also great as a dust protection for your telescope and camera.

Other uses

• As a dust protection of Schmidt-Cassegrain, Schmidt-Newton or Maksutov system or as a dust protection in front of DSLR camera.
• As an alternative instead of the IR-Blocker if your camera has a high sensitivity at short wavelengths.
• As an alternative instead of the MC Clear if your system has any refracting elements

Alternatives

You should think about using the IR-blocker if your camera has a low sensitivity at short wavelengths. Think about using the MC Clear glass if you have a system without any refracting elements. If you do color imaging from light polluted places, please think about using the CLS CCD filter for the luminace data instead!

Suitability

• Visual observation (dark skies): It depends, for dust protection only
• Visual observation (urban skies): It depends, for dust protection only
• Film photography: It depends, for dust protection only
• CCD photography: Very good, if used with optics which contain refracting elements
• DSLR photography (MC modified): Very good, if used with optics which contain refracting elements
• DSLR photography (astro modified): It depends, for dust protection only
• DSLR photography (original): It depends, for dust protection only
• Webcam / Video (Planets): Very good, if used with optics which contain refracting elements
• Webcam / Video (Deep Sky): Very good, if used with optics which contain refracting elements

Technical Data

• Parfocal with other Astronomik filters
• Glass thickness: 1mm
• Completely resistant against high humidity, scratches and aging effects
• Diffraction limited, the filter will not reduce the optical performance of your telescope!
• Astronomik filters are delivered in a high-quality, long lasting, filter box

How to read the above chart?

    * The horizontal axis is the Wavelength in Nanometers (nm). 400nm is deep blue, at 520nm the human eye senses green and at 600nm red. At 656nm is the famous "H-Alpha" emission line of hydrogen.
    * The transmission in % is plotted on the vertical axis.
    * The red line shows the transmission of the filter.
    * Visual filters: The grey line in the background shows the relative sensitivity of the human eye at night. The maximum is at ~510nm and drops to longer and shorter wavelengths. You can easily see, that you can´t see anything of the H-alpha line at night (even if you can during daylight!) The sensitivity at 656nm is 0% at night!
    * Photographic filters: The grey line in the background shows the sensitivity of a typical CCD sensor.
    * The most important emission lines from nebulas are shown in green. The most important lines are from ionized Hydrogen (H-alpha and H-beta) and double ionized oyxgen (OIII) .
    * The most important artifical emission lines are shown in orange. The artifical light pollution is dominated by see mercury (Hg) and sodium (Na), which are used in nearly all streetlights.

The major emission lines of artifical light pollution: | Hg 435,8nm | Hg 546,1nm | Hg 577,0nm | | Hg 578,1nm | Na 589,0nm | Na 589,6nm | | Na 615,4nm | Na 616,1nm |

The major emission lines of nebulas: | H-β 486,1nm | OIII 495,9nm | OIII 500,7nm | | H-α 656,3nm |

Filter image is for demonstration purposes only.