Four images stacked as SDMask in MaximDL Pro and this one was 2-Passes and SigmaFactor 0.10 without IgnoreOver and Normalization: 25% using Linear . The Log showed that 10,000,000 pixels of 24,000,000 pixels had Median applied to them . x CCDWare.com website has a Manual section and 'Stacking' is a good PDF file to read and talks about Sigma and Normalization and 'pixel rejection' .x This is the last evaluation for M16 with … it looks like some low dark area banding is there so ISO3200 might be better . Linear seems a little better than Delta-Level … all images were "Equalize Stretch" to the first image .x The Baader Fringe Killer filter was used which is probably a reflective type filter when you look at it … like a Lumicon DeepSky so photons might have a hard time getting thru and needs a longer exposure … but a Lumicon Minus-Violet filter is easy to see thru and a lesser exposure might work .. but they say use a little longer exposure with the Minus-Violet .x