Just starting out and have a few questions

[fievelgp]

Hey everyone, I'm new here.   I've been lurking in these message boards for a few weeks.   After a few months of watching Youtube videos and such, I decided to finally take the plunge and start my journey into astrophotography.    To start off, I went with a Canon Rebel T7 with the kit lens and the 300mm lens and just a tripod and intervalometer.  I wanted to start small and do wide field tuff and get decent with image processing before dumping a ton of money into things I wouldn't know how to use yet. 

 

My first night out ( I live in a Bortle 6) I used my kit lens at 18mm , 1600 ISO, 3.5 ap, and did 30 sec exposures for about 20 minutes aimed toward Orion since it seemed to be the easiest place for me to aim in my yard.  I have a few questions about how the images turned out and . I'm pretty happy with my results for it being my first time. I don' t think I got the focus right , but I am happy to see the abundance of stars. With the naked eye, you can only see the brighter stars here.      

Both pictures were stacked and stretched in Siril.  The first image was stacked with darks, flats, and biases.   Why does it look so cloudy? Is it from the white shirt I used for the flats ?      The 2nd image is only my stacked lights.  I removed the green tint in Siril. Other than that, the only thing done in both photo's was stretching since I have no idea what I am doing with image processing yet

Any tips for getting a better overall wide field image ? I welcome any and all criticisms ! Thank you!! 

Edited February 4 by fievelgp

[AstroMuni]

On 04/02/2024 at 02:57, fievelgp said:

The 2nd image is only my stacked lights.  I removed the green tint in Siril. Other than that, the only thing done in both photo's was stretching since I have no idea what I am doing with image processing yet

Have you done a background extraction? Can you also attach the flats image here so others can comment.

[alacant]

Hi

T7, so lose both the dark and in-camera bias frames. Instead, simply subtract the offset before stacking. That should clean things up considerably.

Cheers and HTH

[happy-kat]

Hi

Have you checked each file to see if any of your lights have passing cloud as you might want to exclude those from your stack

[fievelgp]

7 hours ago, AstroMuni said:

Have you done a background extraction? Can you also attach the flats image here so others can comment.

I tried my hand at it in Siril but I don't have a good grasp on it yet.  It seemed to make things worse. I'm gonna need to watch some more guides and practice .  I was able to use another editor to clean up the light pollution some, so maybe I need to try other software if I can't figure it out with Siril.

As for the flats, I can but I'm pretty sure I figured out my mistake. The white shirt I used was pretty thin( I only used one layer) and I didn't use a bright white light when I took them *facepalm* 

[fievelgp]

4 hours ago, happy-kat said:

Hi

Have you checked each file to see if any of your lights have passing cloud as you might want to exclude those from your stack

I did. The only thing that passed through my lights was a plane( and maybe a meteorite ?) . I think I figured out my mistake with the flats- I used a thin white shirt( only one layer)  and I didn't take them with a bright light .

[fievelgp]

4 hours ago, alacant said:

Hi

T7, so lose both the dark and in-camera bias frames. Instead, simply subtract the offset before stacking. That should clean things up considerably.

Cheers and HTH

Thank you, I will give this a shot.    Sorry to sound stupid, but what do you mean by subtracting the offset?  

[happy-kat]

8 hours ago, fievelgp said:

 I think I figured out my mistake with the flats- I used a thin white shirt( only one layer)  and I didn't take them with a bright light .

For flats, you'll need aperture, ISO and focus the same as your lights, look at the histogram use your shutter speed to get the histogram light peak in the middle.

Dark flats, cover the light source (lens cap), take dark flats as nothing else changes.

In Siril you can enter a number for a synthetic bias. 

Edited February 6 by happy-kat
Added lens cap for clarity

[Elp]

7 hours ago, fievelgp said:

bright light

You don't want a bright light, it needs to be an even light across the FOV more than anything (this does not mean the flat will be even, the light shining across the FOV has to be even, or diffused as such that it becomes even during the exposure), in fact I diffuse mine so it's quite dim (I use a drawing tracing led panel).

Siril is quite straightforward to use once you know how, the tabs on the RHS of the screen for calibration through to stacking are laid out in a logical order so you use them left to right one after the other.

[Elp]

14 minutes ago, happy-kat said:

Dark flats, cover the light source, take dark flats as nothing else changes.

Cover the lens you mean, best method. Duration per image exposure to be the same as the flats. But using a Canon DSLR you don't usually take any dark frames whatsoever and use @alacants method.

Edited February 6 by Elp

[happy-kat]

Agree darks and bias but in testing with my data I'm undecided and had found dark flats ok 

[alacant]

9 hours ago, fievelgp said:

subtracting the offset

https://linuxcb.blogspot.com/2023/09/siril-dslr-processing.html

HTH

[fievelgp]

6 hours ago, alacant said:

https://linuxcb.blogspot.com/2023/09/siril-dslr-processing.html

HTH

Thank you!

[fievelgp]

Thank you everyone! I appreciate it all!