Astronomik ProPlanet 742 IR Pass Photo Filter 2-Inch
Astronomik 2-Inch ProPlanet 742 IR-Pass Filter for AstroPhotography
Mounted filter in 2" cell ( M48.5mm x 0.75mm )
Ideal filters for the reception of the moon and planets, notably Mars, with telescopes from 6" (150mm) aperture.
The planet IR Pro 742 only allows infrared light with wavelengths of more than 742 nm to pass. In this wavelength range the effects of seeing are significantly lower than in the visible spectrum of the human eye. This allows much sharper images than are usually obtained from your device and location. Another advantage is that the sky background of advanced dawn is dark and so the filter even allows photography of the planets and the moon at daylight.
The Astronomik ProPlanet 742 cuts off the visible part of the spectrum and allows the light of wavelengths longer then 742nm to pass. Due to this behavior the part of the spectrum that is most sensitive to bad seeing is rejected. This approach does a big improvement to the imaging of planets and the moon. The image is more steady than the image in the visible light with nearly identical exposure times.
- Besides astrophotography the filter allows you to get stunning results in nature photography. If an EOS-Clip Filter is used in an MC modified DSLR you get tremendous results imaging the flora. The filter cuts off the part of the spectrum where Chlorophyll looks green and shows its high reflectivety in the near infrared. If trees are photographed in spring and summer under blue skies you get stunning images with white trees and clouds in front of a near black background.
- Darkens the background during twilight.
- Imaging of bright planets, stars and comets by day.
- Imaging of young stars in dust clouds and stellar nurseries.
When the seeing is very bad and the instrument is 10" (250 mm) or larger, the Astronomik ProPlanet 807 may be the better choice.
- Visual observation (dark skies): Unsuitable, the eye is insensitive at this spectrum
- Visual observation (urban skies): Unsuitable, the eye is insensitive at this spectrum
- Film photography: It depends,
- CCD photography: Reasonable, for special IR photography (as chlorophyll)
- DSLR photography (original): Unsuitable
- DSLR photography (astro modified): Unsuitable
- DSLR photography (MC modified): Very good, for IR daylight photography
- Webcam / Video (Planets): Very good, rejects problems with seeing
- Webcam / Video (Deep Sky): Very good, rejects problems with seeing
- more then 96% transmission for wavelengths of 742nm to 1100nm
- blocking of wavelengths between 350nm and 730nm
- 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 filled with grey 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 of the eye 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 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 |