Editing stelle e affini.

“ Modifying digital cameras is not necessary to obtain great astrophotos. Many stock cameras have good hydrogen-alpha response, e.g. recent Canon DSLRs. More important than a modified cameras is proper post processing methods that will bring out and not suppress hydrogen alpha emission, and cameras with good sensitivity and very low thermal dark current. The best digital camera for deep sky astrophotography that I have evaluated has good sensitivity, including hydrogen-alpha, and amazingly low dark current is the Canon 7D Mark II 20-megapixel digital camera. A great full frame digital camera for astrophotography is the Canon 6D 20-megapixel digital camera.

The advantage of a stock digital camera in astrophotography is that the color balance is close to that of the human eye, and shows compositional differences better. Modified digital cameras are too sensitive to hydrogen alpha emission, making scenes containing hydrogen too red, swamping colors from other compositions. Often this shows in amateur astrophotos as dominantly red. The choice of course is personal. I prefer images with more colors to show more processes and chemistry. I believe such images are more interesting, so I only use stock digital cameras for my astrophotography. „

“ Then it is even funnier that critics on the internet insist on many things, like blue star gradients away from the galactic center. The stellar photometry data show such a claim to be bogus. There are other claims, including that one needs bias frames and scaling dark current. But bias is a single value (2048 on the 14-bit camera raw data from the Canon 6D), and the camera has on-sensor dark frame suppression. Thus there is no need for bias frames, nor dark frames, regardless of processing method. Including these just adds noise and that reduces what faint signals can be extracted. That's a hint: do not use the dark frames in your processing if you try the challenge, and use a good modern raw converter. Figure 8 shows the difference in methods and using dark frames. ImagesPlus uses a traditional raw conversion to linear data similar to other astrophoto image processing systems. The image in Figure 8b has lower noise than the image in 8a if bad pixels are not included in the statistics. Dark frame subtraction (8a) removes bad pixels in traditional raw converters. Modern raw converters, like ACR (Figure 8c) use the bad pixel list in the raw file to skip those pixels during raw conversion. ACR also allows noise reduction at the raw conversion level (the amount of noise reduction is completely selectable by the user, so if you believe the noise reduction in Figure 8c is too much, simply choose a lower amount). Trying to do noise reduction on the images in Figure 8a or 8b has a higher chance of making a splotchy background due to the color noise (which I have seen in attempts by some people in this challenge).

It is the lower noise as illustrated in Figure 8c that enables one to pull out more faint detail. The noise reduction produces results similar to much longer exposure times with traditional methods. „

“ Beh no... ma se continui a sostenere che i dark sono da evitare, e che è meglio tenere l'ir-cut (due cose che Clark NON ha detto)... io qua in questa discussione non ho nulla da dare. „

“ Nebulosa NGC 7000 (Nord America) Dettaglio sul "Golfo del Messico" Camera di ripresa: ASI 1600 MC-C Camera di guida: ASI 120 MM Mini Ottica: Imaging Star TS65q Montatura: Skywatcher AZ-EQ5 Synscan Pro Tutto ripreso con AsiAir (un Raspberry Pi3 con tutti i software a bordo) Integrazione: 12x600" Gain 250 Temp -20°C 15 Dark e 30 Bias Umidità: in pratica sono uscito a scattare col boccaglio... „

“ Perdona la franchezza, ma in Astrofoto i risultati sono commisurati all'attrezzatura. „