M27 again with the Canon Rebel T7i for 9-30secISO1600 and 25- 35.9secISO1600 for 34 CR2.s 'Combined' in "ImagesPlus" as 'Sigma Clip Average - std.dev. 2.45' and 32bitFloat-output . I then did the 'Auto-stretch' and the "Stretch for ArcSin" using the 'color' section at the bottom moving the sliders to the right to de-compress the colors , then the sliders above them... I moved the next one up to the right a large amount and then the slider above that just a little tiny amount to the left and then the one above that an amount to the right ..and the top section I left at 'None' because it over-brightens the image too much . I then used the "Color" section's Micro Curves and used the 'Red' option and the 'Saturation' option to cause the more reddened look to the red parts of M27 ...and that was all I did to it except I did a "Geometric" 'Transforms' using the 'Scale at 0.57' which makes the image like a 35mm 'sensor' size like the "Resize" in MaximDL Pro , and "Realign Color" . The jpg is from this result . I put the FITS image into MaximDL Pro and used "Pixel Math" and entered the 'XPIXEL 6.555' and YPIXEL 6.555' and then "Half Size" and 8bit and it 'solved' with the USNO-A2 Catalog and says 1174mmF/L without any description of a magnification theory I was using . The FITS is included . Maybe why the Canon EOS Rebel T7i image with 24.2MP shows a larger image than the Canon EOS 6D with 20.2MP in the MaximDL Pro 'buffer' is because the Rebel T7i is using more computer pixels to show all it's pixels ? , so using the "Resize" to the Canon 6D 35mm size shows the Rebel at it's real size , and image 'object' size . I think I was reading the "Introduction to Digital Astrophotography" by Robert Reeves and on page 160 and Page 161 section 7.4 is a description of why someone would think a Lens or Telescope might have an approximate magnification reality like the mmF/L . It says a camera in 1925 as a 35mm camera had a diagonal measurement of 43mm , so they made a Lens at 43mm and there were abberations at the edges so the made a 50mm Lens and that cured the problem and resembled the way the un-aided human eye sees the area so the theory of 50mm divided into 50mm would be a magnification of 1 power or no magnification ... so if you divide 50 into and mmF/L you might also have an approximate magnification . Also in section 11. about filters it says a Minus-Violet filter will block below 420nm blocking out the 373nm that is a powerful sky pollution nm that causes red nebulosity to look pink in a modified camera , so if it's blocked then the nebulosity would be more red.x
