Night #2 with ZWO Seestar S50: Ring Nebula in 4 minutes.

The image on the left shows the JPEG that comes straight out of the Seestar S50. The image on the right is the exact same raw data from the Seestar S50, but processed through PixInsight.

The image on the left is a 2:1 blowup of a cropped region of the whole image frame. (M57 is pretty tiny in the frame) The image on the right is a 1:1 blowup of the same region after drizzle integration with an expansion factor of 2.

The difference is quite understandable for an inexpensive product. But the raw data coming from the Seestar S50 shows that it has a lot of potential for quality data. This image is from only 4 minutes of exposure time (24 x 10s) on the sky. No filters were used, save for the IR Blocking filter on the sensor, and its Bayer matrix. I find this pretty astonishing for such an inexpensive and easy to use telescope.

Details of the PixInsight processing (not very much):
  1. DeBayer each raw FITS file using VNG interpolation.
  2. StarAlign each deBayered raw frame using the middle exposure of the group as the reference image.
      Generates initial Drizzle info, to become augmented by ImageIntegration in step 3 below.
  3. ImageIntegration using Average, Additive with Scaling, PSF Signal Weight, and Generate Drizzle info.
      This step builds a first integrated linear data image, but also augments the Drizzle info from step 2.
      Be sure to enable Windsorized Pixel Rejection lest hot pixels show up as new stars after deconvolution.
      (If you skip this ImageIntegration step, since we aren't planning to use the integrated image, then step 4 will fail due to incomplete Drizzle info.)
  4. Stack using DrizzleIntegration with a Scale of 2, and a Drop Shrink of 0.9
  5. Plate solve using script ImageSolver (needed for SPCC)
  6. Color calibrate using SPCC with an A0V star as the white reference.
  7. Deconvolve blur and aberrations using BlurXTerminator with default settings (0.5 Star Sharpen, 0.0 Adj Star Halos).
      7a. AutoSTF at this point, then leave alone.
  8. Noise removal with NoiseXTerminator default settings (Denoise 0.9, Detail 0.15). Be sure *not* to AutoSTF after doing this.
      (If you AutoSTF at this point then you might have trouble stretching the image... just a forewarning...)
  9.  Histogram Stretch with the STF setting from 7a.
 10. Apply gentle background deemphasis with Curve, pulling just the 0.25 RGB level down to 0.125. Increase low-end Saturation below 0.5.

Done!