The image was obtained in Bortle 8 sky on Feb 10, 2023.
Camera: stock Canon 90D
Lens: 300 mm f/2.8 + 2x TC (600 mm f/5.6)
Tracked with iOptron HAE29EC mount with no guiding.
Star background: 143 8-second exposures with the 300 mm lens and no TC (ISO 1600 f/2.8)
The comet was imaged with the TC, 393 images at 8-seconds each, ISO 3200, 600 mm f/5.6.
Total exposure time: 19 minutes on stars, 52.4 minutes on comet.
Raw conversion in rawtherapee to Rec2020 color space. This raw
conversion is a full calibration with flat field (in the lens profile),
bias subtraction (bias is in the exif data). The Canon 90D blocks
dark current in hardware with On-Sensor Dark Current Suppression
Technology.
https://clarkvision.com/articles//dark-current-suppression-technology/)
Stack on stars with Deep Sky Stacker. DSS failed with stack on comet, so I
stacked on comet with ImagesPlus.
Stretch each stacked image with color preserving rnc-color-stretch:
https://clarkvision.com/galleries/gallery.astrophoto-1/web/comet-c2022ztf+mars-2023-02-10-btl8-rnclark-strs19m+comet53m.d-c1.33xs.htmlthat also subtracts sky glow in one step.
Comet reduced 2x in size to match star field.
Merge the 2 stacked images in photoshop.
Color managed workflow in Rec2020 color space throughout.
I set the sky level a little lower than I normally do to crush the
sky noise and provide better contrast with the faint part of the tail.
Gallery image and more info here:
https://clarkvision.com/galleries/gallery.astrophoto-1/web/comet-c2022ztf+mars-2023-02-10-btl8-rnclark-strs19m+comet53m.d-c1.33xs.html
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