Experience with Astronomik ProPlanet 642 BP IR-Pass filter on the Moon

My first experience with the IR-Pass filter.

The filter is used for image-based IR photography, high-resolution lunar and planetary photography, and deep-sky astrophotography of H-alpha nebulae. The filter offers three filters in one, depending on the camera used.

1. IR photography with a digital camera

2. It reduces seeing and improves contrast in planetary and lunar imaging.

3. An affordable H-alpha filter for getting started with deep-sky astrophotography of H-alpha nebulae.

 

"BP" is an abbreviation for "Bandpass": The filter opens at 642nm and closes again at 842nm, blocking long-wave infrared radiation, unlike the other two Pro Planet filters. It reduces seeing and enhances contrast in high-resolution planetary and lunar photography. The filter screws into the front of the camera's lens barrel. It is available in 1.25" and 2" sizes. I tested it with the ASI 120 MCS and the Celestron Maksutov Custom 127/1500 telescope.

Examples on the Moon with the same equipment:

Without filter

Mit Filter : 



The seeing was slightly better for this image, and the images weren't taken on the same day.

No filter.





With filter

I was surprised by the filter's effect. The seeing improved, and it reduced atmospheric turbulence by about 30-40%. The contrast and clarity are definitely better. This filter is ideal for 5-6 inch telescopes and larger; there are others for larger apertures. For these shots, I removed the IR cut filter from the ASI (it's a small filter disc that sits on a rubber base over the sensor. Unscrew it, remove it, and you're done).

The Astronomik ProPlanet 642BP is a bandpass filter that allows almost only infrared light to pass through. You CANNOT take true RGB images with this filter; for that, you would need to use an L-filter, which blocks IR. Then the RGB Bayer matrix on the camera's sensor would work, and you would get a color image. Using both IR-pass and IR-block filters in one shot makes little sense. It would be simpler to leave the cap on the lens...

Regards, Rudi Rakete