Methane-filter - which one is best?
Dear Team Baader-Planetarium,
since I am using your 8nm Methanband Filter (#2458295), I am really looking forward to the new Jupiter season 2017. It gives a different and special view of the giant planet, and I really really like it!
Ok, the image is not that bright, since most cameras are not very sensitive at this wavelength, but when using apertures bigger than 150-200mm one can get stunning views of Jupiter and the other gas giants.
Someone may ask: what is this Methanband filter good for and why is it that narrow?
Images done in Methane-band are looking quite similar to images taken in the infrared part of the spectrum. They are showing deeper and warmer details. Storms like the Great Red Spot shine brightly, while the normal clouds are much darker. The latest impacts into Jupiters atmosphere where also well detectable. The moons appear very bright too, since they reflect the sunlight almost completely. Jupiters normal atmosphere leaks within the Methanband (at 889nm), and reflects almost no sunlight, but allows thermal radiation of lower atmosphere layers to clearly shine through.
The effect is similar on Saturn. The planet itself becomes obviously darker, while the rings remain relativly bright. Also a good opportunity to hunt for faint moons of the giant planets.
There are some other Methanband filters on the market in the meantime, but none of them is as narrow as this Baader-Filter. The problem of broader Methanband filters, e.g. 20nm or 50nm, is the huge amount of obfuscating red light within the desired bandpass. At it's best, a broad Methane filter will only provide a high contrast IR-pass image, but the real Methane-effect will be washed out. All those wider methane-filter-results will show slightly emphasized storms, but again - this can be done with any IR-pass filter just the same.
So, in my eyes, the Baader 8 nm Methane-filter with it's very narrow HBW is absolutley on top. Best in detail and contrast.