Astronomik IR Planet Pro 807

During 2006, the german firm Astronomik introduced two new IR pass filters of excellent quality, the IR Planet pro 742 and IR Planet pro 807. Being myself a very satisfied user of their LRGB filters set since 2003, I was curious to try those products, and this is why I bought the 807. I had long hesitated with the 742 but I had already a good filter at 700 nm with the IR70 Murnaghan. The idea was to switch with the Schuler IR78, with a filter with a better mean transmission between 700 and 1000 nm.

The glass is surprising at first as you can see light through it with unaided eye. As I first though to have received a defectuous filter, the Mecastronic society learned me that this one the interferometric type, not as the other IR pass filters who are "died in the mass". There is really a residual transmission in visible light and even a noticeable UV leakage (see curve), but in CCD they have no consequences as the chip is much more sensitive to the IR transmission of the filter.

At use there is no problem at all with the images and the 807 now occupies on my equipment the role the IR78 once played. For those who would like to buy a first IR pass filter, however, the 742 is now currently the probable best choice on the market. The IR 807 is a complementary tool.

- Infrared imaging of the planets
- Excellent image steadiness, especially when seeing is bad

Mars 28 november 2007 - Cassegrain 250, SKYnyx 2-0M Same remarks as with the comparison between IR70 and IR78 : apart of a small albedo difference at the polar caps, the lower resolution of the IR807 makes it less interesting on Mars than any 700 nm filter.
Saturn 9 april 2007 - Cassegrain 250, SKYnyx 2-0M Because of the weak resolution, the filter doesn't look interesting for Saturn. Use a 700 nm filter instead. That last one will be used at F/30 better than F/24 here.
Jupiter a) 9 april 2007 - Cassegrain 250 - SKYnyx 2-0M à F/24 b) idem but on 31 july 2007 Maybe more interesting on Jupiter - the typical aspect of the planet is enforced in comparison with 700 nm filters. The contrast looks increased also. However, the difficulty of use makes those differences hard to detect as the technical quality of the images is generally low. During 2007, the filter was used with profit because of the low altitude of the planet. It many times produced a sharper image than the IR70, despite a much lower frame rate (25 fps for the 700 nm, only 10 for the 807).
Venus 3 may 2007 - Cassegrain 250 and SKYnyx 2-0M The IR 807 filter is now the only IR filter I systematically used on Venus. Without any problem of image brightness on this planet, it's interesting to use "deeper" IR filters. Moreover, 700 nm filters do not contrast enough the IR details visible on Venus. Those details are clouds located at a lower altitude than those visible to the human eye.