Do cooled OSCs need calibration frames?

ISV5b7CK

New to astrophotography. Using an ASI2600MC Air mounted to an AM5N.

Lots of conflicting information regarding the use of calibration frames, which likely stems for the individuality of a person's equipment and preference. As I understand it, calibration frames can play an important role in producing the highest quality stacked image.

My question for this cooled OSC is... WHICH calibration frames are actually needed/preferred? I'm reading about Bias, Dark, Flat and Dark Flats.

I've made several runs at the above (except dark flats) so far. But I'm reading that bias frames for a cooled OSC might cause more issues than they solve. Is that where the dark flats come in?

Any help and perspective appreciated!

starvoyager

For Deep Space Astrophotography…..,
Others will probably disagree but I listen to the developers of various software for my technical reasoning plus observing my results over years

In regard to the benefits of good calibration, there’s simply no substitute for a clean dust spot free , corrected evenly illuminated flat field with no vignetting to give your images the best starting point upon commencement of post processing.
You owe it to both your camera and yourself.

I image from both Bortle 8 heavy light polluted skies ( backyard in a big City ) and from my NexDome located under Bortle 3 dark skies
I’ve used both ZWO2600MC and ZWO2600MM cameras for the past 7 years

Telescopes 6” , 8” and 10” carbon Newts

My calibration recommendation …..,

Darks to calibrate your Lights
Flat Darks to calibrate your Flats

All frames same Temperature, same Gain , same camera orientation
Darks to match Lights exposure
Flat Darks to match Flats exposure

I create a Dark library to cover most of my Light frame exposures and Gain settings for Broadband and Narrowband. My library is good for 12 to 15 months before creating a new one.

Why use Flat Darks in lieu of Bias ?
Flat Darks are the Gold Standard for Calibration of Flats regardless of CMOS camera type and brand
They don’t take too much time or effort after your session or on another night provided you don’t move the image train / camera.

The Sony IMX571 sensor still exhibits RTN ( random telegraph noise ) in the form of hot pixels so Darks will totally eliminate this issue ( even if you cool your camera to -10C to -15C )

There are no short cuts in Calibration, spend the time and effort and your images will benefit.

PS: I forgot to mention about Dithering !!
Dithering is just as important as Calibration when it comes to improving your images
Dithering eliminates fixed pattern noise like walking noise , vertical and horizontal column noise and similar types of noise

Clear Skies
Martin

ISV5b7CK

Martin, thank you. An absolutely fantastic response.

I also just bought "The Deep Sky Imaging Primer" which, along with the guidance you provided, should assist with getting things set up smartly.

Much appreciated.

starvoyager

Glad to offer my experiences

Here’s some info on Calibration…..,

In regard to Flats with the 2600MC, the IMX571 sensor is reasonably forgiving

Broadband ( no filter , just the internal UV/IR cut )
Aim for a target ADU of 25,000 to 32,000
Aim for exposure of between 0.2sec to 1sec

Narrowband ( Dualband or Triband )
Aim for a target ADU of 25,000 to 32,000
Aim for exposure of between 2 sec to 5 sec

Flats same Gain , same temperature as Lights

Quantity of Flats 30 to 40

Flat Darks same exposure as Flats , same gain , same temperature

Quantity of Flat Darks 30 to 40

Dark Library
Same exposure as Lights , same gain , same temperature
Exposure series ( Broadband and Narrowband) to match Lights
Quantity of Darks 30 to 40

Clear Skies
Martin