M81 - Attempt #2

[Jonny_H]

Hi all,

I had another go at M81 last night.  I pushed the boat out and tried experimental 10 minute exposures x 10 @150 gain.

Stacked in APP and a bit of post processing in PI.  Still learning but think I am getting there slowly but surely.

 

Clear skies,

Jonny

 

[malc-c]

Is this just stacked lights? - Did you take any darks or flats ?

[Jonny_H]

1 hour ago, malc-c said:

Is this just stacked lights? - Did you take any darks or flats ?

No this was stacked with 60 flats and 60 bias also. Admittedly I didn't take any darks yesterday but plan on doing so this evening and will re-stack with darks included.

Just out of interest - why do you ask? I am fairly new to this so would like to learn from my mistakes etc....

[malc-c]

It was the background of the star field.  I'm no expert when it comes to imaging, but I just had a hunch that something was "missing".  Most people seem to miss out the flats or bias images, tending to use lights and darks only.  You may find you get a lot more contrast by adding the darks...  It's a nice image and some nice round pinpoint stars so tracking was good too...

[Jonny_H]

21 minutes ago, malc-c said:

It was the background of the star field.  I'm no expert when it comes to imaging, but I just had a hunch that something was "missing".  Most people seem to miss out the flats or bias images, tending to use lights and darks only.  You may find you get a lot more contrast by adding the darks...  It's a nice image and some nice round pinpoint stars so tracking was good too...

Thanks for this. 

As mentioned I am planning to capture the darks this evening and re-stack. I have a cooled camera which makes life a little easier in this regard.

[almcl]

That's a pretty good image!  

I've run your png through StarTools and got this result.  Some processing artefacts (my fault for going too quickly) and two satellite trails but lots of detail!  The satellites will disappear if you have more images and stack with a Sigma Clip. Or you could discard the subs with them on - but with only 10, that might not be a good idea?

Pixinsight can probably do a very similar job.

Are you using a light pollution filter?

 

 

Edited March 31, 2021 by almcl

[Jonny_H]

2 hours ago, almcl said:

That's a pretty good image!  

I've run your png through StarTools and got this result.  Some processing artefacts (my fault for going too quickly) and two satellite trails but lots of detail!  The satellites will disappear if you have more images and stack with a Sigma Clip. Or you could discard the subs with them on - but with only 10, that might not be a good idea?

Pixinsight can probably do a very similar job.

Are you using a light pollution filter?

 

 

That's great. Far better than my processing attempts. Thank you.

Is StarTools easy to use compared with the likes of PI?  PI is rather complex! 

Edited March 31, 2021 by Jonny_H

[almcl]

Startools is easier to use with the defaults, but there is still a learning curve.  You can download a fully functional version (with just 'Save' disabled) that has no expiry date,

Ivo Jager its author gave a demo in Stargazine episode 41,  it's available to watch in the Stargazine section.

[Jonny_H]

1 hour ago, almcl said:

Startools is easier to use with the defaults, but there is still a learning curve.  You can download a fully functional version (with just 'Save' disabled) that has no expiry date,

Ivo Jager its author gave a demo in Stargazine episode 41,  it's available to watch in the Stargazine section.

Thank you.

I will download it and have a play

Currently shooting my dark frames so once complete I will re-stack and process to see if I can get a better contrast.

[malc-c]

Here's my result - taken Monday evening when the Moon was at 98%, so the sky was quite challenging.

12 x 360s exposure @ ISO400  and 20 x 360s @400ISO darks.  Stacked in DSS and then I had the Wizard Mr David Davies process them as I was struggling with stretching the data.

 

 

My monitors acting strange as from one angle it may look dark, the other it's stretched too far and all the dust bunnies are visible - so on your screen it might look anywhere between !

Camera is a modified 400D - no IR filters . 

[Jonny_H]

Thats a lovely image.  Lots of detail there!

[Jonny_H]

I've given processing another go.......this time with 10 x 600 sec darks.  I think i just need to learn how to post-process properly! 😆

 

 

[malc-c]

On 31/03/2021 at 23:23, Jonny_H said:

I've given processing another go.......this time with 10 x 600 sec darks.  I think i just need to learn how to post-process properly! 😆

 

 

 

LOL - You can include me in that camp....  I find it very frustrating when you gather hours worth of data, stack them and then get disappointing results especially when you know there is more details in the result, even after hours of fiddling with stretching and colour matching etc.  My friend who is (IMO) at the top of the game when it comes to imaging (his main camera cost more than my 8yr old Volvo V70 !!) and has had many an image featured  in Astronomy Now  to my subs and performed some magic on it and got the result above ! - Would love to know what his secret is