Processing process for deep sky imagers

johnk

Hi everyone,

enjoying seeing the Deep Sky images being posted here. Curious to know some information about Deep Sky Imaging with the ASI camera range particularly about Darks and Flats and the temperature control with the BETA testers on the cooled cameras.

So here come the questions!

- With the latest version of Firecapture how does the temperature of the camera get controlled and how are Darks and Bias Frames added? or are Darks and Bias frames added later?

- Are people capturing using SER, AVI or BMP files?

- For Staking, is everyone using Autostakkert? Can you add Darks and Bias frames here? for LRGB processing does everyone use mutli-point alignment for their mono images and then combine them in Photoshop?

Any other processing routines for LRGB processing with these CMOS cameras would be appreciated.

Clear skies,

John K.

maurizio

Actually I'm doing like this.

1- My camera is an ASI120MM

2- Iim capturing in AVI format using FireCapture subtracting only the dark

3- I do not take separate darks/flats

4- My DIY cooler is manually controlled through an electronic regulator, I read and control the temp. on the preview and when I think is well stabilized I start to capture the dark and LRGB AVIs

5- Next I stack in Registax and pre process (little wavelts and more gain curves)

6- Since my pics are BW I have to merge in an RGB format, which I'm doing in paintshop using a layer for a single component.

7- For RGB I use the Lighten Blending mode, but the Difference works fine too

8- For the Luminance I'm using the Luminance blending

9- Each Layer has obviously to be manually aligned before merging

10- when the picture's components are merged then I apply some corrections and filter in Paintshop.

Clear Skies

betacapricorni

Bellissima maurizio! Quanti light sono?

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betacapricorni

I'm sorry..... I wrote in italian :)

Outstanding Maurizio! How many lights are? Which peltier controller do you use ?

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firstc8

I agree, stunning image. Maybe I should consider a cooled mono.

Although imaging and processing seem daunting for me at this time. But nothing has stopped me so far, not yet.

maurizio

Thanks everibody.

First the sky is the most important factor, if it is dark an transparent all works much more finer, less noisy more contrast... you know.

In this case (M27) the sky was pretty good even from Milan's hinterland.

So I took about 50x12sec RGB Full Res and no Luminance because thin clouds were passing over M27 just after B capture and stayed there : for a long while.

About the peltier controller: I'm actually using a DC motor regulator for radio controlled aeromodels.

This regulator is a PWM chopper (On/Off), powered from a 12V DC /5 A source. So the peltier is powered by a continuous train of pulses at 3kHz and 12Vcc amplitude, whose duty cycle is controlled by the regulator. Then using a servo tester connected to the regulator I can manually control the duty cycle by a knob, and the power to the peltier.

E.G. RC Model Power regulator

Servo Tester

This is a picture of the Whole system

maurizio

Just to be clearer.

There are 2 kinds of speed controllers for RC models: The "Brushed" Motor Control and the "Brushless" one.

You must use the Brushed type wich has 2 output wires to connect the brushed motor (or the peltier).

The Brushless type has 3 output wires to connect brushless motors (3 phase motors), and will not function in our case.

Generally the speed controller's cost depends by the max current they can handle. In this case a cheap 10A regulator is 4 to 5 times capable to handle the peltier current load.

betacapricorni

Thank you Maurizio but i'm not able to use speed controller, welder or similar.... I'll use mi 120mc peltier simply cooled.... I placed the peltier in the back of the camera, with cooling sistem. Milan Hinterland where if i can? I lived in south hinterland for 33 years now i live near Pavia

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maurizio

Hi Beta Cap.

I'm living in Cologno Monzese

maurizio

firstC8 wrote:
Although imaging and processing seem daunting for me at this time. But nothing has stopped me so far, not yet.

@firstC8:

If you just want to play with RGB here you are some pictures to mix and align.

maurizio

and here you are the Luminance too

landbo

JohnK wrote:
Hi everyone,

- Are people capturing using SER, AVI or BMP files?

Hi John.

You must use the formats of files that fits your job bedst.

-A AVI video may contain only frames with a color depth for of 8 bits per channel (RGB or b/w).

-A SER video may contain frames with a color depth for both 8 or 16 bits per channel (RGB or b/w).

-BMP Format can contain an image with a color depth for of 8 bits per channel (RGB or b/w).

-PNG, TIF or FIT format may contain an image with a color depth for of 8 or 16 bits per color channel (RGB or b/w).

It is not certain that the various programs available and use all the listed formats, so you have to choose from what the intended application can use. FIT is the image format normally used for DSO work.

Common to all the formats you use, they do not contain any destructive compression. In fact you do not normally compression for astrophotography.

For planets it commonly has only 8 bits of video (AVI)

For sun and moon max color depth the camera can deliver (SER).

And for DSO work color depth the camera can deliver (FIT).

Hope the above text can help you further.

Regards Leif.

landbo

JohnK wrote:
Hi everyone,

- For Staking, is everyone using Autostakkert?

-Can you add Darks and Bias frames here?

- for LRGB processing does everyone use mutli-point alignment for their mono images and then combine them in Photoshop?

Any other processing routines for LRGB processing with these CMOS cameras would be appreciated.

Hi again.

Normally, AutoStackkert 2 is only for planet and sun/moon processing. However, there is a beta version which should be suitable for the DSO to work with a short exposure time.

A good program for preprossing of planet and sun/moon is PIPP. The program can also conveterer between different video / image formats you normally use for astro.

A good stacking program for DSO's are DSS.

Alternatively, Regim be used. It's a really good program for stacking.

Other programs you may enjoy could be Registax, Iris and FitsWork4.

All these programs have their own download sites that you can visit via eg. Google. Tip, search the program's name and astro, you can avoid most of the pages are not relevant.

These programs are all free, but if you use them a lot, I suggest you donate a small amount to the authors who have spent much time to create there software.

Regards Leif.

betacapricorni

Landbo wrote:
JohnK wrote:Hi everyone,

- Are people capturing using SER, AVI or BMP files?

Hi John.

You must use the formats of files that fits your job bedst.

-A AVI video may contain only frames with a color depth for of 8 bits per channel (RGB or b/w).

Hi Landbo

The avi file has only 8 bits depth per channel? The 120mm/mc are 12 bit camera am i right? How i may take videos at 12 bit? I remember that with the first 120mm ( without ST4 ) in Firecapture there was 12 bit option, now there is 16 bit option so i thought that every video was at 12 bit. Am i wrong?

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riklaunim

SER, TIFF, FITS can save > 8 bit data.

landbo

betacapricorni wrote:

Hi Landbo

The avi file has only 8 bits depth per channel?

The 120mm/mc are 12 bit camera am i right?

How i may take videos at 12 bit?

I remember that with the first 120mm ( without ST4 ) in Firecapture there was 12 bit option, now there is 16 bit option so i thought that every video was at 12 bit. Am i wrong?

Hi.

-Yes.

-Choose 12 bits in the program you use to read camera data. Then the program will choose a file format that can hold the 12-bit (SER if video).

-Then the first 4 bits will contain zero and the remaining 12 containing your camera data.

Regards Leif.

betacapricorni

So, i've to choose 16 bits on firecapture and .ser as output file? Am i right? I don't know where, in FC, i've to choose 12 bits

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landbo

betacapricorni wrote:
So, i've to choose 16 bits on firecapture and .ser as output file? Am i right? I don't know where, in FC, i've to choose 12 bits

Sorry, do not knowing so much around that program FireCapture. But you should select 12 bit somewhere in the setup for your camera. You must try it out for yourself.

Regards Leif.

betacapricorni

Thank you so much!

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johnk

Great information sharing guys - thanks all.

One of the issues I see in capturing several thousand frames over several hours (the whole night form me) is with a non permanent set up (again me!) some field rotation and the somewhat varying quality of the frames to to the effective focal length.

The beauty of AS2 is it's ability to sort the frames in order of quality and then stack. But it will struggle to stack with field rotation. Is this correct?

So, if this is the case, the only way to then overcome field rotation is either for Emil to add this as a feature of AS2 in the future, or to pre-sort the frames in PIPP, choose the best ones and then use DSS as per normal (for me) to Stack, add Darks, Bias and Flats. So SER, AVI files are out of the picture here, so need frames in BMP, TIFF or FITS for DSS. However, the banding issues that has been discussed with the CMOS cameras then needs to be sorted afterwards.

I am not sure to what extent the new cooled cameras from ZWO will have set point cooling, but my thinking will be to build a set of dark frames with pre-set gain/exposure levels which reduce noise and minimise the banding issue that was being discussed with CMOS chips (if possible)

Any more thoughts from anyone? and comments on my logic regarding the above?

Thanks again.

John K.