BP is an abbreviation for bandpass: the filter opens at 642 nm and closes again at 842 nm. Unlike the other two ProPlanet filters from Astronomik, it blocks long-wave infrared light.
Together with the Astronomik ProPlanet 742 and ProPlanet 807 filters, you can now choose three wavelength ranges for infrared photography to get the best results.
With the ProPlanet 642 BP, you get three filters in a single product: depending on which camera you use the filter with, it is a great tool for infrared photography with a digital camera, reduces seeing and enhances contrast in high-resolution planetary and lunar photography. It is also an inexpensive H-alpha filter for getting started in deep sky astrophotography of emission nebulae.
Infrared photography:
- High-contrast images with excellent colour differentiation
- Great reproduction of the Wood effect
- Avoidance of hot spots
- Exposure times as under "normal light"
- Great for IR film photography!
High-resolution moon and planet photography:
- Short exposure times
- Effective reduction of air turbulence (seeing)
- Enhanced contrast in the red range
- No ghost images and optimum sharpness thanks to blocking of long-wave IR
Deep sky astrophotography of H-alpha nebulae:
- Maximum transmission of the H-alpha line at 656 nm
- Enormous contrast gain under light-polluted skies or in moonlight
- Inexpensive entry into H-alpha photography
- Easy focusing with LiveView possible!
Additional application: Guiding in astrophotography. The 642BP in front of your autoguider significantly improves the quality of your tracking, as it minimises image jumps caused by seeing!
Our expert comment:
The filters fit Canon full-frame cameras. Operation is only possible with the mirrors fully raised. 5D MK II, 5D MKIII and 6D can be focused easily using Live View. The 5D MKI only works without Live View. The 6D MkII, 5DS, 5DSR and 5D Mk IV models do not work.
The mounted XL clip filter fixes the swing mirror in the upper position. The optical finder cannot be used while an XL clip filter is mounted. Focusing, searching for and centring objects can only be done via the Live View monitor on the back of the body or via the camera's remote control using a USB cable. All functions such as autofocus and image stabilisation remain available.
(Bernd Gährken)
