Ring M57

Discussion in 'My Astrophotos' started by ROBERT T SCHAEFER JR, Jul 18, 2018.

  1. ROBERT T SCHAEFER JR

    ROBERT T SCHAEFER JR Cyanogen Customer

    Joined:
    May 13, 2018
    Messages:
    256
    M57 with a Canon EOS Rebel T7i 'modified' 188xpowr ' 125secISO6400 for eight RAWMono AutoSaves thru MaximDL Pro V6.16 .
    This image as a jpg was done at a Bin1 stage and I tried "Curves - Luminance" trying to bring out the dim nebula ... It didn't do
    too good because the larger stars became blocky looking with squares in them .?. So I did 'Undo' and I searched for another
    method which would be like a Lewis and Clarkexpedition .... but I thought I would try "Levels" and use the RGB Gamma and I
    toggled the Gamma down to ' .5 ' which becomes over-bright and pale and faint as a 16BIT and pressed OK . ... but 8BIT can be
    used instead like on the 8Bit FITS that I sent .... ; so with the image I was doing at 16Bit 0-65535 or an 8Bit 0-255 you then 'open'
    the "Histogram Stretch" command and have your 'screen-stretch' at 'Max-Val' and select the radio button for 'Straight-Line' which
    is a diagonal line without inner points and starts at the top left and goes down to the bottom right .. the bottom right point must be at the
    bottom right or the white parts of the Ring will over-brighten . The image will transform into an over-exaggerated color combination....
    but you then use the 'screen-stretch' 'Red' carot and slide it to the right till the background around the Ring becomes dark like the nite sky and
    the Ring will be bright and you can use the 'Green' carot to increase brightness a little bit to search for small tiny stars if they are in the image .
    This is a sure-fire plan for this particular 'object' . ... using the other radio button options have the right bottom point too high which causes
    the white part of the Ring to over-brighten . I tried "Deconvolve" and it doesn't really do too much so ...initially... the "Levels" and then the
    "Histogram Stretch" are the only commands I used .x

    I was doing the Cat's Eye Nebula with 2minISO6400 and you could see if you were in 'focus' but with
    ISO12800 for 2min or 90sec the image had an over-saturation artifact so that won't work , lower than
    ISO12800 with a Canon Rebel is what to use ... maybe a CCD Camera works the same with an
    over-saturation point and then the Gain needs to be reduced imitating an ISO selection .x
     

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