Finally, some month after I purchased the Baader Ultra-Narrowband SHO filterset optimized for f/3 optics, I could try it out on this very well known target.
Such narrow filters require long exposure times to swamp the read noise, however my setup is not protected against wind and so I decided to use 300s exposures as a compromise.
Although a lot of subframes had to be sorted out, I could collect enough good subframes to process this image and the resulting noise was on an acceptable level.
Compared to the 7nm filters I used before at my light polluted place, the result is - as I hoped for - superior, even though less integration time was used:
M16 in SHO 
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