TheSkySearchers

Hi Steve,
Thanks for posting this tutorial. I appreciate that the software has been updated since but I'm confused about calibration frames.
Flats, I totally understand. They remove vignetting and dust bunnies. I use a Geoptic flat panel and NINA's flats wizard to ensure the exposures are correct.
I also understand not to bother with bias frames as they can introduce unwanted noise.
Both my astro cams have zero amp glow so I assume taking darks of the same duration as the lights is pointeless but darks flats? The current version of WBPP doesn't seem to know what dark flats are which suprises me. I've tried adding dark flats and it seems to stack them into a master and subtract them from the lights. I've since not bothered with any dark frames at all and just use flats. I hope someone can point me in the right direction because it's becoming very confusing. Guess the question is, should I just use flats?

Clear skies
Pete

Hi Pete,

I cannot answer for Steve, but me, personally, I include darks, dark flats, flats, and lights in WBPP. I also use a zero amp glow camera (ASI533MC).
Possibly, I am stuck in my old school methods, but I like the results that I get from WBPP's pre-processing and it takes little time to produce darks and even less producing dark flats.

You also have good results in pre-processing, so use what works for you. As long as you don’t see any hot pixels in your master light, you should be good. Donyou ise CosmeticCorrection in WBPP?
Or, you can spend some time comparing methods to confirm your choices.

Same as Jim, I include lights, darks, flats and flat darks in WBPP. Following Steve's advice, I don't capture bias frames when using a CMOS camera. The flat darks go in with the normal darks. PI sorts them out based on matching their exposures with the flat frame exposures. But as Jim says, use what works for you.

Graeme

Hi Jim,
Thanks for your reply. Seems there's a bit of "black art" with calibration frames and as you say, use what works for you. I don't have hot pixels on my OSC Player One camera but have them on my ASI 553MC. I find dithering get's rid of both hot pixels and colour walk. I dither every 5 frames and it seems to work for me. I've not done much imaging recently due to bad weather but I've spent a huge amount of time optimising my rigs. I've done various filter trials which was very interesting to say the least and shimmed the cameras to optimise back focus. I'm trying to fine tune everything to save fixing problems in processsing. How much of an improvement it will make I've no idea, just need some clear skies now. Sorry went a bit off topic there.

Clear skies
Pete

Graeme1858 wrote: ↑Wed Nov 08, 2023 3:19 pm Same as Jim, I include lights, darks, flats and flat darks in WBPP. Following Steve's advice, I don't capture bias frames when using a CMOS camera. The flat darks go in with the normal darks. PI sorts them out based on matching their exposures with the flat frame exposures. But as Jim says, use what works for you.

Graeme

Thanks Graeme, that's two of you that take darks and dark flats. Next session I'll stack with them and compare.

Pete

I too take flats, darks, dark flats.

I've never heard of a modern CMOS camera that didn't have hot pixels, BTW.

AstroBee wrote: ↑Wed Nov 08, 2023 3:42 pm
I've never heard of a modern CMOS camera that didn't have hot pixels, BTW.

Thanks for mentioning that. My P.O. cam is on a 135 lens so it's widefield and full of stars. I zoomed in and can see them now.

Pete

Petrol wrote: ↑Wed Nov 08, 2023 9:03 pm

AstroBee wrote: ↑Wed Nov 08, 2023 3:42 pm
I've never heard of a modern CMOS camera that didn't have hot pixels, BTW.

Thanks for mentioning that. My P.O. cam is on a 135 lens so it's widefield and full of stars. I zoomed in and can see them now.

Pete

Completely normal. Cosmetic Correction is really easy to set up and apply in WBPP.

I'll bet that your images are full of stars! Have you counted them?
On a recent image of the Perseus Double Cluster, I used the ImageSolver script in PI to count the stars. With my small 533 sensor, I counted over 34k!

Juno16 wrote: ↑Wed Nov 08, 2023 11:34 pm

Petrol wrote: ↑Wed Nov 08, 2023 9:03 pm

AstroBee wrote: ↑Wed Nov 08, 2023 3:42 pm
I've never heard of a modern CMOS camera that didn't have hot pixels, BTW.

Thanks for mentioning that. My P.O. cam is on a 135 lens so it's widefield and full of stars. I zoomed in and can see them now.

Pete

Completely normal. Cosmetic Correction is really easy to set up and apply in WBPP.

I'll bet that your images are full of stars! Have you counted them?
On a recent image of the Perseus Double Cluster, I used the ImageSolver script in PI to count the stars. With my small 533 sensor, I counted over 34k!

I'll try cosmetic correction in WBPP Jim thanks.
On my widefield rig I've seen 54K. They say that 1 in 10 stars has a solar system, it's mind boggling!

Pete

Just to add, I've taken some dark frames and was suprised how noisy they were. Thanks for the help.
Pete

Petrol wrote: ↑Sat Nov 11, 2023 9:05 pm Just to add, I've taken some dark frames and was suprised how noisy they were. Thanks for the help.
Pete

The dark frames only look noisy because I'm guessing you are auto-stretching them in PI? Because the images are completely dark by nature, PI does an extreme auto stretch on them to try and bring out any potential detail in an "image".
Most modern CMOS sensors are very clean in comparison to older CCD's and even the earlier model CMOS sensors.