Astronomik ASIRBP6422 - ProPlanet 642 IR Band Pass Filter, 2", Planetary Filter

The Astronomik ProPlanet 642 BP is the lastest addition to the family of Astromik ProPlanet IR-pass filters. The filter thrills because of its wide range of applikations for daylight IR photography, high-resolution lunar and planetary imaging and for taking beautifull and deep images of H-alpha regions when used for astrophotography.

"BP" are short for "Bandpass": The filter gives you a 200 nm spectral window from 642 nm to 842 nm. 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!

With the Astronomik ProPlanet 642 BP, you get three filters in one product: depending on the camera, it is a fine tool for daylight IR photography with a digital camer, reduces seeing and enhances contrasts in high-reslution planetary and lunar imaging and is a economically-priced H-alpha filter for the start into deep-sky astrophotography of H-alpha nebulae.

How it works:

The ProPlanet IR 642 reduces dusturbing atmospheric affects when creating monochrome planetary and lunar videos. This is achieved through a transmission window where the wavelangth range has to fullfill a couple of requirements:

the unsharpness which is caused by vertical motion of air in the atmosphere (seeing) are minimized

the camera sensitivity is used best

the wavelength range is tuned to the resolution and correction of the telescope.

The filter is designed for (astronomical webcams without built-in IR blocking filter or MC-modified DSLR cameras with video function. The wavelength range which passes the filter is a mixture of seep red and short wave infrared. Thus the filter is usable for colour imaging with the Astronomik L-RGB filter set for replacing the L filter under bad seeing, so that clearly sharper and less deformed images can be achieved. This enhances the usability of the images in postprocessing considerably. By including the H-alpha and [[S II] lines, it is a wide-band, but economically priced alternative to pure line filters of those wavelengths.

The focal range for getting optimal results can be found between f/1 and f/30.

Deep-sky astrophotography:

At the well-known H-alpha emission line, the ProPlanet 642 BP reaches its mmaximal transmission of almost 100%. Whereas all photons of the beautiful H-alpha regions hit the sensor, shorter wavelengths with the bulk of the light pollution are blocked. If using an astronomically modified camera, the bandwidth is reduced to 40 nm. The result is an enormous gain in contrast due to a darker sky background.

Daylight IR imaging:

One initial point when develloping the ProPlanet 642 BP was daylight imaging with (modified) digital cameras.

For normal photography, an IR blocking filter is mounted directly in front of the sensor in the camera, as the sensors are sensitive up to more than 1100 nm. By removing this built-in filter, a camera can be used for the very interesting IR photography.

The Astronomik ProPlanet 642 BP starts transmittion in the deep-red spectral range and lets pass all light up to 842 nm. Thus you get images perfectly suitable for channel selection and allows for an outstanding color separation in postprocessing, as the starting wavelength of 642 nm, combined with blocking long-wavelength delivers especially constrasty images.

Other uses:

The Planet IR 642 Pro BP is suitable exclusively for cameras without IR blocking filter.

Especially with colour cameras without IR blocking filters, it is the best to take monochrome images, as the Beyer matrix is not defined in IR and the camera gets "color-blind". The Astronomik Planet IR 642 Pro BP is not suitable for solar observation or photography, even if used with a sun filter.

Alternatives:

For luminance exposures (monochrome cameras) or colour imaging in the visual range, we recommend the Astronomik L filter. For pure IR exposures, we recommend the Astronomik ProPlanet 742 IR pass-filter or Astronomik ProPlanet 807 IR pass filter.

If the seeing is not so bad or if the telescope is smaller than 10" (250 mm), we recommend the use of the Astronomik ProPlanet IR 742.

If the seeing is very bad and the instrument is 10" (250 mm) or larger, the Astronomik ProPlanet IR 807 may be the better choice.

Suitability:

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 on the film

CCD and CMOS photography: Neutral, can be used as an inexpensive H-alpha filter

DSLR photography (original): almost unusable

DSLR photography (astro modified): economically priced alternative to H-alpha filters

DSLR photography (MC modified): Very good, for IR daylight photography

Webcam / Video (Planets): luminance exposures at higher seeing

Webcam / Video (Deep Sky): experimental

Technical Data:

more then 95% transmission for wavelengths of 642 nm to 840 nm

blocking of wavelengths between 350 nm and 630 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