Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

The Great Hercules Cluster

  • Please log in to reply
14 replies to this topic

#1 fmeschia

fmeschia

    Surveyor 1

  • *****
  • topic starter
  • Posts: 1,597
  • Joined: 20 May 2016
  • Loc: Mountain View, CA

Posted 18 June 2021 - 07:03 PM

Hello experienced astroimagers,

 

I've been doing some imaging practice from home with my new ASI294MM camera. Over the course of four nights of this week I managed to capture a bit over 15 hours of data from M13. They all were nights of very good seeing, and as a result the image seems particularly sharp and detailed to my eyes. The limiting magnitude is upwards of 19.5 and probably around 20, and by pixel-peeping around M13 I found several distant clusters of galaxies, the most distant of which has a redshift of 0.50, placing it at a comoving distance from us of over 5.5 billion light years.

 

I'm just at the beginning of my run with this mono camera, but I'm blown away at how much sharper and deeper images I can produce, compared to my familiar DLSR.

 

Full capture data and high-res imagery is available at https://www.astrobin.com/giu59n/ – and it really begs to be looked at in high resolution!

 

As usual, any comment or critique is very welcome.
Francesco

 

Flickr:

51251523513_a95b475612_k_d.jpg

 

Astrobin:

get.jpg?insecure


Edited by fmeschia, 18 June 2021 - 07:50 PM.

  • paul hart, StephenW, DeanS and 29 others like this

#2 Dynan

Dynan

    Fly Me to the Moon

  • *****
  • Posts: 6,027
  • Joined: 11 Mar 2018
  • Loc: NOLA

Posted 18 June 2021 - 07:14 PM

The 'Propeller' has been seen. Great image!



#3 coopman

coopman

    Fly Me to the Moon

  • *****
  • Posts: 7,045
  • Joined: 23 Apr 2006
  • Loc: South Louisiana

Posted 18 June 2021 - 07:14 PM

WOW, that is a great image.  Sharp and colorful.  Thanks.



#4 Stellar1

Stellar1

    Apollo

  • -----
  • Posts: 1,349
  • Joined: 08 Dec 2018
  • Loc: Ontario, Canada

Posted 18 June 2021 - 07:14 PM

This is a wonderful image of M13, you are right in saying it particularly sharp and detailed indeed, stars are beautiful pinpoints and colors are great. When it comes to technical aspect of imaging I am not the guy as I dabble in planetary only but, it doesn't take a crack shot imager to know beautiful when they see it.



#5 mashirts

mashirts

    Viking 1

  • *****
  • Posts: 618
  • Joined: 18 Sep 2014
  • Loc: Elgin, TX

Posted 18 June 2021 - 07:38 PM

+1 about all the admiration of your photo. Really stunning to view.

#6 paul hart

paul hart

    Surveyor 1

  • *****
  • Posts: 1,835
  • Joined: 01 Jun 2004
  • Loc: 50 M East of NYC

Posted 18 June 2021 - 07:57 PM

Absolutely stunning!



#7 GDAstrola

GDAstrola

    Vostok 1

  • *****
  • Posts: 166
  • Joined: 17 Jan 2018
  • Loc: St. Louis

Posted 18 June 2021 - 08:21 PM

Astronomics would do well to have that wonderful image posted with their scopes. 



#8 KTAZ

KTAZ

    Surveyor 1

  • *****
  • Posts: 1,932
  • Joined: 09 Apr 2020
  • Loc: Scottsdale, AZ

Posted 18 June 2021 - 08:31 PM

Very nice detail and color!



#9 fmeschia

fmeschia

    Surveyor 1

  • *****
  • topic starter
  • Posts: 1,597
  • Joined: 20 May 2016
  • Loc: Mountain View, CA

Posted 18 June 2021 - 09:01 PM

Thank you all very much, I’m humbled by your appreciation!



#10 B 26354

B 26354

    Vanguard

  • *****
  • Posts: 2,024
  • Joined: 05 Jan 2017
  • Loc: Southern California semi-desert (NELM mag 5.3)

Posted 18 June 2021 - 09:05 PM

Wow, Francesco, that is truly wonderful. I can't stop looking at it.    bow.gif



#11 bobzeq25

bobzeq25

    ISS

  • *****
  • Posts: 25,104
  • Joined: 27 Oct 2014

Posted 19 June 2021 - 10:49 AM

Very nice image, but I'm going to jump off this train, just a bit.

 

With a modern CMOS camera (low read noise), you want to shoot shorter subs.  Particularly in Bortle 7.  300" has blown out a lot of star cores.

 

This video will give you some suggestions.  They're an excellent place to start.  Look at the exposure table at about 50 minutes.  You may now pick your jaw off the floor.  <smile>  Note that they're for L, you multiply by 3 for RGB.

 

https://www.youtube....h?v=3RH93UvP358

 

People often shoot too long subs when moving from a DSLR.  You, of course, want to maintain total imaging time by shooting more of them.  I built a new processing computer to help, but then I was moving to an F2 RASA, also.



#12 fmeschia

fmeschia

    Surveyor 1

  • *****
  • topic starter
  • Posts: 1,597
  • Joined: 20 May 2016
  • Loc: Mountain View, CA

Posted 19 June 2021 - 11:02 AM

Very nice image, but I'm going to jump off this train, just a bit.

 

With a modern CMOS camera (low read noise), you want to shoot shorter subs.  Particularly in Bortle 7.  300" has blown out a lot of star cores.

 

This video will give you some suggestions.  They're an excellent place to start.  Look at the exposure table at about 50 minutes.  You may now pick your jaw off the floor.  <smile>  Note that they're for L, you multiply by 3 for RGB.

 

https://www.youtube....h?v=3RH93UvP358

 

People often shoot too long subs when moving from a DSLR.  You, of course, want to maintain total imaging time by shooting more of them.  I built a new processing computer to help, but then I was moving to an F2 RASA, also.

Thank you for the suggestion. I think the saturation problem is bit overblown (pun intended), at least in this image. Here’s a map of the pixels with values > 80% of full range, for the R channel. As you can see, only a handful of stars are approaching saturation.

 

Saturated-R.jpg

 

Of course, in a different field the situation would have been different, and I would have used a different strategy.


Edited by fmeschia, 19 June 2021 - 11:02 AM.


#13 bobzeq25

bobzeq25

    ISS

  • *****
  • Posts: 25,104
  • Joined: 27 Oct 2014

Posted 19 June 2021 - 11:23 AM

Thank you for the suggestion. I think the saturation problem is bit overblown (pun intended), at least in this image. Here’s a map of the pixels with values > 80% of full range, for the R channel. As you can see, only a handful of stars are approaching saturation.

 

attachicon.gifSaturated-R.jpg

 

Of course, in a different field the situation would have been different, and I would have used a different strategy.

Look at the final images you've posted, here and on astrobin.  There are many more stars with white cores than that.  Some people do like that, I prefer more color.

 

Personal deal.  I use archsinh stretch to help with that.

 

The only thing I will say is 300" is too long, that's DSLR territory.  F7, Bortle 7, image scale 1.3.  Glover is recommending 30".  He made the video because he saw that many people were overexposing subs with modern CMOS cameras with low read noise (note the difference in the chart with the two read noises).  They have excellent dynamic range, but need to be handled appropriately.

 

I'd say your truth is somewhere in between.  <smile>


Edited by bobzeq25, 19 June 2021 - 11:32 AM.


#14 fmeschia

fmeschia

    Surveyor 1

  • *****
  • topic starter
  • Posts: 1,597
  • Joined: 20 May 2016
  • Loc: Mountain View, CA

Posted 19 June 2021 - 11:30 AM

Look at the final images you've posted, here and on astrobin.  There are many more stars with white cores than that.  Some people do like that, I prefer more color.

 

Personal deal.  I use archsinh stretch to help with that.

 

The only thing I will say is 300" is too long.  F7, Bortle 7, image scale 1.3.  Glover is recommending 30".  I'd say your truth is somewhere in between.

But that’s after stretching, right? It has nothing to do with whether the data was saturated in linear form. The map I’ve posted was calculated on the master R light still in linear form.

 

Arcsinh stretch does work wonders. In fact, I have used it as the first stretching step for this very image. 

 

[Edited: for some reason I had written “master dark” instead of “master light”. Go figure...]


Edited by fmeschia, 19 June 2021 - 07:35 PM.

  • bobzeq25 likes this

#15 gundark

gundark

    Viking 1

  • *****
  • Posts: 590
  • Joined: 07 Jun 2015
  • Loc: Southern California

Posted 19 June 2021 - 12:26 PM

Wonderful job with this image! Sharp and colorful. 




CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics