ΦΙΛΤΡΟ ASTRONOMIC ASIR2 IR-CUT 2''

Φίλτρο Astronomic ASIR2 IR-CUT 2"

This IR blocking filter should be used as a standard at all imaging applications with sensors having a low sensitivity in the UV. Put this filter in front of your camera and you will get rid of all problems caused by IR like bright halos around all objects and a very soft overall image.

If you compare the transmission data of the Astronomik IR-blocker with the data from other sources, you will notice, that most other manufacturers would call this already an UV-IR blocker. The filter Astronomik calls an "UV-IR blocker" is superior to any UV-IR blocker from other manufacturers worldwide!

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

Main use: The IR Blocker gives you a perfect parfocal filter. It blocks all IR light without modifying the visual part of the spectrum. It is also great as a dust protection for your telescope and camera.

Other uses:

• As dust protection of Schmidt-Cassegrain, Schmidt-Newton or Maksutov systems or as dust protection in front of DSLR cameras.
• As an alternative instead of the UV-IR-Blocker if your camera has a low 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 UV-IR blocker if your camera has a high 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 luminance 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 and CMOS photography: Very good, if used with optics which contain refracting elements
• DSLR photography (original): It depends, for dust protection only
• DSLR photography (astro modified): It depends, for dust protection only
• DSLR photography (MC modified): Very good, if used with optics which contain refracting elements
• Planets: Very good, if used with optics which contain refracting elements
• Deep Sky: Very good, if used with optics which contain refracting elements

Technical Data:

• Transmission of 97-99%
• Extremly steep edge at approx. 685 nm
• Parfocal with other Astronomik filters
• Glass thickness: 1 mm
• 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.

Filter transmission curve:

• The horizontal axis is the wavelength in nanometers (nm). 400 nm is deep blue, at 520 nm the human eye senses green and at 600 nm red. At 656 nm 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 ~510 nm 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 656 nm is 0% at night!
• Photographic filters: The grey line in the background shows the sensitivity of a typical astro camera sensor.
• 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 most important emission lines from nebulas are shown in green. The most important lines are from ionized hydrogen (H-alpha and H-beta), double ionized oyxgen ([O III]) and ionized sulfur ([S II]). The square brackets indicate that these lines are forbidden.