Diffusing the Situation

8/09/2024. The backwash of a tropical storm promised good skies tomorrow but then surprised me with several good hours today. I auditioned a new flatfield diffuser. Daystar sells them for $85-99 plus tax and shipping. Mine is made from an embroidery hoop (~$2.00 at Amazon) and a snippet of the translucent plastic bag the Post Office uses to keep packages dryish when dropped off in the rain. I'm sure the Daystar diffuser works well, but this DIY version seems pretty good, too.

As usual, click anything for a closer look.

 

12x Best 100 of 500, no gamma, processed twice (edge and disk). North up, east left.
(Today's was the highest sunspot count in 20 years.)

 

Best 100 of 5,000 (1000x750 ROI) Oriented however I found it.

 

Best 100 of 5,000 (1000x750 ROI) x 2 (extreme left and remainder)

 

There are two things done differently in the second and third images. First, rather than use defocused flats, these were flat-fielded using the stretched postal plastic diffuser (single layer; 100ms, 64 flats). And second, I've used "Smart Blur" to unharsh the edges of one and noise reduction to do the same for the other. "Smart Blur" will repay systematic experimentation.

 

2024/08/10. These are the skies I was promised, though with a few more clouds to dodge than I expected. I removed the reducer for a little extra image scale which likely worked more against me than for me (live and eventually learn?). The exposures are longer for any given gain (on the order of 3ms at g350) and gamma (usually about 27), and the first, in particular, suffers from excess scale. Maybe forego the R.O.I. thing when working at this scale? See the last image on this page for an alternative. These, too, are made using the new diffuser with a 1000x750 region of interest. The processing steps for all incorporated a "surface blur" step. They're the best 300 of about 4,000 frames except the prominence photo which is the best 100 of 1,800 (either gamma off or gamma ~75 -- I can check the logs if it matters).

 

Best 300 of 4,000 x2 (top, bottom). No R.O.I. No reducer.

 

 

 

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