a good experiment... This image was at Bin1 with pixel size 3.72microns and then at Bin2 to make the 'false-color' image with the "Color StacK" command and made to a finished JPG and then "Half Size" for the finished FITS image . Smoothing was needed and "Curves-Luminace" to the UHC image to brighten the stars before making it Mono . \\\\\\\\\\\\\\\ WITH_THIS example of 6-frames of UHC and of Baader 7nm Ha at 100secISO3200-6400 . I left as Bin1 and a "Convert Color" to each image without any other command and leaving them as the Bin1 size , I did this to each filter type 'light' frames ;;; I then I used the STACK command and first I did Sigma-Clip 'Linear' and Normalization: 30% and Sigma-Factor: 9.5 for the UHC and Baader 7nm Ha filter 'light' frames and I used the Sum for the 300sec and 400sec ISO3200 and ISO6400 'light' frames . Then I did the 'screen-stretch' to show the most and then "Color Balance -Scaling 100% and 'Auto' for Background" , and then the "Stretch" command to make the image 16BIT then "Save As..." a 16Bit stacked FITS for each filter type . These un-cropped images show differences in stacking methods trying to retain faint light-shades in the images without removing too much data as Bin1 'light' frames before stacking , but to get the 'false-color' to happen OK I had to make the Mono version of each filter type a Bin2 ?????!!! //////// . S234567 ()()() ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- 152mm A+M Refractor(OfficinaStellare-1200mmF/L) using a TeleVue 2XPowerMate for an effect of 2400mmFL using a Lumicon UHC(wide-band OIII) 2in. filter . **** I did RAWMonochrome images thru MaximDL Pro V6.16 . {{{{{{{{{ When I changed to the SII filter after the UHC images while doing M16.... the ASCOM Astro-Physics V2 Driver wanted to 'update' and wouldn't 'connect' ; it took about 35 minutes to get the laptop going again after it decided to 'Restart' itself last night Aug. 2 2021 or I would have got more images .... and the sky was clear . }}}}}}} *****x Also , the DSLR's 'Long Exposure Noise Reduction ON' was used .******** . I did do what Astro-Physics site said which was go to ASCOM and download the latest Platform and then I 'installed' it . I went back to the Astro-Physics site and followed the link to Ray Garalak's ASCOM Astro-Physics V2 Driver and I downloaded and 'installed' the v5.30.00 Driver which replaced the v5.10.02 Driver I was using }}}}}}}}}}.... and the second night Aug. 4 2021 I started imaging the 'M27 Dumbbell Nebula' as UHC-SII-Ha , but UHC and Ha were really dim at 100secISO3200-6400 for three images each ISO for each filter and I Sum stacked the two separate filter types ; and SII for 300secISO3200-6400 for one each ISO and 400secISO3200-6400 for one each ISO was also dim ... I Average stacked the SII filter type , And then I made them Mono to use the "Color Stack" for a false-color image . I'l try again with some longer exposures for the UHC filter type for more flaring light to see if that helps ... otherwise regular color images might be better . +++++++ The 'Backyard Astronomer's Book' says they always use the DSLR's 'Long Exposure Noise Reduction ON ' which is on page 305 top right instead of 'dark-frames' . Also , it seems as though the Sulfur-II (SII) filter with the Astronomically friendly Hutech modified DSLR needs three times the exposure length as the UHC and Ha filters because the DSLR's internal cut-off filter only allows about 20% passage of the SII region. ^^^^^ The Ray Gralak site had a PDF file describing some of his image processing software and Median combine rejects the two upper and two lower pixels values in a pixel leaving the 'median' value which has less SNR ; the Average combine has better SNR but doesn't eliminate artifacts ; the Min-Max/SigmaClip discards the highest and lowest pixel values in a pixel but at least ten images are needed ; and the SDMask combine you might use Normalization 30% and 'Linear' and SigmaFactor: 0.5 which should discard the highest and lowest pixels values in a pixel but uses a lot of RAM and CPU to do it with 3-Passes . With this M27 image I used the Sigma-Clip for UHC and Ha and the Sum for the SII images hoping not to reject any values in each pixel trying to use all of a pixel's values . x
