Astronomik ProPlanet 642 BP IR-pass Filter

Astronomik ProPlanet 642 BP IR-pass Filter

  (2 Reviews)
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About this product

Model:  ak_pp_642-bp_2
Part Number:  10227200

The Astronomik ProPlanet 642 BP offers a wide range of applications for daylight IR-Photography, high-resolution lunar and planetary imaging and for taking beautiful and deep images of H-alpha regions when used for Astrophotography.

"BP" are short for "Bandpass": The filter gives you a 200nm spectral window from 642nm to 842nm. Contrary to the other two ProPlanet filters it blocks the longer infrared. Together with the Astronomik ProPlanet 742 and the ProPlanet 807 you can now have three choices to match your needs when imaging in the IR. The Astronomik ProPlanet 642 BP will be the right choice for the best image quite often! 


  • More then 96% transmission for wavelengths of 642nm to 840nm
  • Blocking of wavelengths between 350nm and 630nm
  • Optically polished substrate, striae-free and free of residual stresses
  • Not sensitive to high humidity or aging effects
  • Scratch-resistance!
  • 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

Three Filters in One! 

Depending on your camera, the Astronomik ProPlanet 642 BP is a great tool either for daylight IR-imaging with your digital camera, or it will reduce seeing effects and enhance contrast when used for lunar- and planetary imaging, and third it will be a very good and low-priced H-alpha Filter for getting started in Deep-Sky Astrophotography of H-alpha regions. 

Daylight IR-imaging

  • Short exposure times, about the same as normal VIS-imaging

  • Perfect choice for Infrared-Videos

High-resolution Lunar and planetary imaging

  • Short exposure times

  • Effective reduction of Seeing

  • Enhanced contrast

  • No ghosts and best sharpness due to blocking the longer IR

Deep-Sky Astrophotography of HII regions

  • Best transmission of the H-alpha line at 656nm

  • About 40nm FWHM with astro-modified DSLRs

  • Amazing contrast under light polluted skies or moonlight

  • Low priced filter for getting started in H-alpha imaging

  • Easy focussing using camera display plus LiveView!

Guiding for Astrophotography

  • installing the 642BP in front of your guiding camera dramatically improves guiding quality, as image-motion from one frame to the next is minimised.

Transmission 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 blue line shows the transmission of the filter.
  • The most important emission lines from nebulas are shown in orange. The most important lines are from ionised Hydrogen (H-alpha and H-beta) and double ionised oxygen (OIII).

The major emission lines of artificial 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

Technical Data

  • More then 96% transmission for wavelengths of 642nm to 840nm
  • Blocking of wavelengths between 350nm and 630nm
  • Parfocal with all Astronomik filters
  • Thickness of 1mm
  • Not sensitive to moisture, scratch resistant or ageing
  • Optically polished substrate, striae-free and free of residual stresses
  • Astronomik filters are delivered in a high-quality, long lasting, filter box


Customer reviews

Average Rating (2 Reviews):  
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Rating (max 5):  
A complete set across 400nm to 1100nm.
Tuesday, 9 March 2021  | 

I purchased this to complete the set for use with an ATIK 383L+ and a EFW2 filterwheel. The complete set is Baader-C, Baader-R, Baader-G, Baader-B, Baader-L, ProPlanet-642, ProPlanet-807, Staranalyser-100, and a solid blank for darks. This gives me two different sets across the 400nm to 1000nm window, i.e. Penta-colour (R, G, B, 642, 807) and Tri-colour (L, 642, 807). The Atik 383L+ is sensitive between around 300nm and 1050nm. At the IR end there is a massive atmospheric absorption spike around 1100nm so there is no point going past there. Between them these filters chop the range that most CCD sensors can cover into usable chunks. I might now look for a low pass filter stopping at 400nm to replace the Baader-C, although it is useful to have a wide filter for focusing and target alignment. Perhaps I don't need the blank for darks perminantly fitted, the camera does have a darks shutter.

Rating (max 5):  
As good as expected
Tuesday, 25 August 2020  | 

I've been using it only once until now. I captured Saturn via a SC 9.25 XLT telescope with 2,5 x Barlow lens and Zwo ASI camera. The quality of the final image become essentially better than without this filter, in spite of the fact that the max altitude of the planet is ab. 6 degrees here in the Middle Finland now. So, highly recommended !


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