M13 5/6/21 - feedback/thoughts appreciated

[R1k]

Shot M 13 last night. Happy with this overall for the integration time but was quite disappointed to see that the faint stars in the central cluster were very soft, despite excellent focus with APT's Bahtinov Aid. Is this likely to be a feature of my seeing/Bortle class (6)? 

 

Equipment:

- Skywatcher EQ6R-pro

- ZWO ASI 294MC-pro

- Explore Scientific ED APO 102mm F7 FCD-100 Triplet Carbon Fibre

- Hotech SCA 1x field flattener

- ZWO ASI-120MM-mini guide camera

- Skywatcher Evoguide 50ED guidescope

- Optolong L-pro

 

Acquisition:

- Sharpcap polar alignment, ASCOM guiding/dithering with PHD2

- APT image acquisition

- Lights – 70 x 30s and 50 x 60s at -15c, gain 125, offset 30

- Darks – 30

- Flats – 30

- Dark flats - 30

[scotty38]

It looks great to me and sharper than mine at 382mm with a GT81 and 0.8x flattener, same camera. Plus I can't work out how to get the star colours 🙂

 

 

 

Edited June 5, 2021 by scotty38

[AstroAndy]

Hi R1k

Could be the seeing..if you're imaging at F7, you might get away w/ 20s subs, or even 15, maybe that'll mitigate the softness.

Andy

[AstroAndy]

@ Scotty

Don't want to hijack this thread, but here is all kinds of color info. in your image. There are more ways than one to bring it out.

If you're a Photoshop user, one easy way is:

1) Duplicate the image (Background, background copy)

2)Go to .Filter > Noise . Dust & Scratches, and blur your image so that you only see the brightest stars (in your case, you'll also see a blob in the middle, M13)

  (Radius about 9, threshold 0)

3) In the image pane on the right, chose blending mode darken ([most] of your DSO will disappear, if not, experiment w/ radius until it [mostly]} does

4) Go to select . color range (have "quickmask on"), and mark the biggest star with the leftmost eyedropper tool, then mark a few smaller stars w/ the middle

   eyedropper tool

5) You'll see "marching ants around your stars. Go to select > modify > expand, expand by 2-3 pixels

6)Go again to select, feather by 1-2 pixels

7)Then delete the top layer (background copy), the marching ant stars will show up on the first layer

8)Go to layer >New > via copy

This gives you a separate star layer

9) Go to image > adjust > match color, and move the slider way up (this can be done more than once, however, after each iteration, change the blending mode to "color').

Done (you could also use saturation), the change will just show up on the stars, not the DSO or the background).

Hope that helps.

Andy

[bottletopburly]

21 hours ago, R1k said:

Shot M 13 last night. Happy with this overall for the integration time but was quite disappointed to see that the faint stars in the central cluster were very soft, despite excellent focus with APT's Bahtinov Aid. Is this likely to be a feature of my seeing/Bortle class (6)? 

 

Equipment:

- Skywatcher EQ6R-pro

- ZWO ASI 294MC-pro

- Explore Scientific ED APO 102mm F7 FCD-100 Triplet Carbon Fibre

- Hotech SCA 1x field flattener

- ZWO ASI-120MM-mini guide camera

- Skywatcher Evoguide 50ED guidescope

- Optolong L-pro

 

Acquisition:

- Sharpcap polar alignment, ASCOM guiding/dithering with PHD2

- APT image acquisition

- Lights – 70 x 30s and 50 x 60s at -15c, gain 125, offset 30

- Darks – 30

- Flats – 30

- Dark flats - 30

loveley image the core looks a bit green  had a crude play in Startools hope you dont mind , neutralized green in colour module and use hdr module using detail range to resolve detail in stars just to see if it made a difference 

[scotty38]

13 hours ago, AstroAndy said:

@ Scotty

Don't want to hijack this thread, but here is all kinds of color info. in your image. There are more ways than one to bring it out.

If you're a Photoshop user, one easy way is:

1) Duplicate the image (Background, background copy)

2)Go to .Filter > Noise . Dust & Scratches, and blur your image so that you only see the brightest stars (in your case, you'll also see a blob in the middle, M13)

  (Radius about 9, threshold 0)

3) In the image pane on the right, chose blending mode darken ([most] of your DSO will disappear, if not, experiment w/ radius until it [mostly]} does

4) Go to select . color range (have "quickmask on"), and mark the biggest star with the leftmost eyedropper tool, then mark a few smaller stars w/ the middle

   eyedropper tool

5) You'll see "marching ants around your stars. Go to select > modify > expand, expand by 2-3 pixels

6)Go again to select, feather by 1-2 pixels

7)Then delete the top layer (background copy), the marching ant stars will show up on the first layer

8)Go to layer >New > via copy

This gives you a separate star layer

9) Go to image > adjust > match color, and move the slider way up (this can be done more than once, however, after each iteration, change the blending mode to "color').

Done (you could also use saturation), the change will just show up on the stars, not the DSO or the background).

Hope that helps.

Andy

Thanks Andy much appreciated. I am not a photoshop user but do have PI and Affinity so will use your tips and try and replicate using those tools....

[R1k]

On 05/06/2021 at 19:53, AstroAndy said:

Hi R1k

Could be the seeing..if you're imaging at F7, you might get away w/ 20s subs, or even 15, maybe that'll mitigate the softness.

Andy

Thanks very much. 

[R1k]

22 hours ago, bottletopburly said:

loveley image the core looks a bit green  had a crude play in Startools hope you dont mind , neutralized green in colour module and use hdr module using detail range to resolve detail in stars just to see if it made a difference 

This looks great! Thanks for having a go.