Trying to process without flats in Pixinsight

[Ivor]

After too many small technical problems I finally managed to get a set of guided subs, however I've not built my flat light source yet so I'm looking for some recommendations on strategies to get around that and continue practicing my processing. I've tried one approach for a synthetic flat which didn't come out well so keen to hear some recommendations.

The attached image was created with the following Pixinsight working flow:

• Image Calibration with Master Dark and Superbias (21 light Subs @ 300s)
• Cosmetic correction 
• Sub frame selection
• Debayer
• Star Alignment
• Local Normalization
• Image Integration

It has been about 5 years since I last tried to produce an image so I'm confident I've missed something.

 

[Rallemikken]

I always take my flats agains an even , open daytime sky. I am cautious not to let sunlight come dowm the tub (reflector guy). Prefer even, cloudy skies, or at dawn/dusk. 30 - 50 images, histogram at center. Same focus as if I was imaging. Works for me.

 

Edited December 17, 2022 by Rallemikken

[Ivor]

Sky flats are an option in the interim, however the weather in the UK is rarely consistent enough to get a clear sky (and I'm not in the office) close to the imaging night. To be honest I'm also hoping to use this exercise to learn my way around Pixinsight new toolset as things have to move on a bit in the last few years.

[teoria_del_big_bang]

1 hour ago, Ivor said:

The attached image was created with the following Pixinsight working flow:

• Image Calibration with Master Dark and Superbias (21 light Subs @ 300s)
• Cosmetic correction 
• Sub frame selection
• Debayer
• Star Alignment
• Local Normalization
• Image Integration

It has been about 5 years since I last tried to produce an image so I'm confident I've missed something.

 

If you have Pixinsight then you can do all of the above using the WBPP script.
Search for tutorials on WBPP, Adam Bock has some great ones, I think some are free to watch.

Steve

[teoria_del_big_bang]

You can try using DBE in Pixinsight to at least improve vignetting and maybe some dust bunnies but probably nowhere near as effective as a good master flat.

Steve

[pipnina]

31 minutes ago, Ivor said:

Sky flats are an option in the interim, however the weather in the UK is rarely consistent enough to get a clear sky (and I'm not in the office) close to the imaging night. To be honest I'm also hoping to use this exercise to learn my way around Pixinsight new toolset as things have to move on a bit in the last few years.

If you have a white shirt, like the business style ones, you can pull that taught over the camera lens/telescope end and keep it that way with a rubber band. Ensure there are no wrinkles or creases. Then point the lens/scope at a computer screen or ipad or television showing a white image. Many screens have colour or brightness shift off-axis but the shirt mitigates this, and helps you produce valid flats post-imaging!

As long as your focus position is very close (ideally the same) as it was before, you should be good!

[City9Town0]

I use multiple layes of white, well ironed, pillow case against a reasonable 'even' piece of sky. Seems to work for me.