Quote:
Originally Posted by gregbradley
Thanks Allan.
It would suit those who use illuminated discs for making flats as then you can control the exposure length to just one length rather than it shifting with dusk flats.
It's a bit of a trial and error approach as to what works and what doesn't.
Hi Martin, it's a QHY600mm and read mode 0 with gain of 26 and offset of 40. Ideally I would use 26 50 for narrowband but it starts to get too complicated as it requires its own set of darks etc.
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Greg,
Here’s an interesting document I found on the IMX455 sensor , well worth a read , if you have the time.
As with the IMX571 , the IMX455 sensor does exhibit random telegraphic noise RTN or 1/f noise ( salt and pepper noise ) which can be mitigated using Darks correction.
https://research.iac.es/preprints/files/PP23035.pdf
Even though it’s a minor problem and only visible when you zoom in and compare bright and darker areas of your image , I take the hard road and use the full calibration suite for all my images as I’ll do anything to improve an image even if it’s ok.
I also read somewhere that these sensors are prone to slight changes in QE ( negative output response ) after 12 to 18 months of use and that Darks are the only sure way to combat this deterioration which include warm pixels and RTN.
Full calibration suite
Darks from Library matched for Lights
Flat Darks for Flats
Using Flat Darks or Bias do not show much difference but I choose Flat Darks as a safe measure.
I capture my Darks library every 9 to 12 months ( I do it in my study ( darkened ) just with the camera itself and cap on , takes a day )
For Flats I use an LED light panel with dimming control and works a treat . The IMX571 in my 2600MM is very co operative ( I believe the IMX455 is as well ) and flats are quick to capture with during a session or after a session during the afternoon or evening.
I have no patience for Sky flats as your options are limited and variable.
Cheers
Martin