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

M17 Tri-band Vs. No Filter

Astrophotography CMOS Imaging Reflector
  • Please log in to reply
10 replies to this topic

#1 Mikeiss

Mikeiss

    Viking 1

  • *****
  • topic starter
  • Posts: 517
  • Joined: 15 Sep 2012
  • Loc: Tucson

Posted 27 May 2024 - 06:17 PM

Here is a comparison of M17 the Swan nebula taken with my Vixen ED81S with the .67 reducer and my ASI174MC-Cool. I originally intended to use my Antlia Tri-band filter, but I forgot and ended up shooting with no filter at all. I then got roughly the same amount of time but this time with the filter. For fun I also tried using both pictures, using the shot with no filter for my luminance frame, and the shot with the Tri-band for the RGB. I like them all, but I'm curious to know what someone else thinks. The shot w/no filter was 213x60s, and the shot with the filter was 225x60s. Due to their file size I'll have to make an additional post for the extra pics. Thanks for looking and clear skiessmile.gif

 

-Mike

Attached Thumbnails

  • M17 213x60s 5-6-24_GraXpert_Siril_PS 75.jpg

  • mikewayne3 likes this

#2 Mikeiss

Mikeiss

    Viking 1

  • *****
  • topic starter
  • Posts: 517
  • Joined: 15 Sep 2012
  • Loc: Tucson

Posted 27 May 2024 - 06:18 PM

The shot with the Tri-band filtersmile.gif

Attached Thumbnails

  • m17 225x60s 5-13-24_GraXpert_Siril_PS 75.jpg

  • mikewayne3 likes this

#3 Mikeiss

Mikeiss

    Viking 1

  • *****
  • topic starter
  • Posts: 517
  • Joined: 15 Sep 2012
  • Loc: Tucson

Posted 27 May 2024 - 06:21 PM

Last but not least, the image where I combined themsmile.gif

Attached Thumbnails

  • m17 211x60s_No filter Lum_223x60s Tri-band RGB 70.jpg

  • mikewayne3 likes this

#4 Mikeiss

Mikeiss

    Viking 1

  • *****
  • topic starter
  • Posts: 517
  • Joined: 15 Sep 2012
  • Loc: Tucson

Posted 27 May 2024 - 06:25 PM

I forgot to list the programs used for processing, oops. DSS, Graxpert, Siril and Photoshop CS4.


  • Cryhavoc38 likes this

#5 licho52

licho52

    Viking 1

  • -----
  • Posts: 731
  • Joined: 15 Dec 2020

Posted 27 May 2024 - 10:13 PM

Filter never adds, only subtracts, you gain nothing from a non-narrowband filter.

 

Narrowband filters work but only because of the narrow part and the narrower the better.  These broad-filters that promise magic are just glass beads.



#6 Mikeiss

Mikeiss

    Viking 1

  • *****
  • topic starter
  • Posts: 517
  • Joined: 15 Sep 2012
  • Loc: Tucson

Posted 27 May 2024 - 11:37 PM

I use the filter for light pollution and it does that fairly well. It's not like I said "look how much better this is with the filter." And I like it which is what matters.  Good day



#7 Cryhavoc38

Cryhavoc38

    Ranger 4

  • *****
  • Posts: 331
  • Joined: 06 Jan 2023
  • Loc: Woodinville, WA

Posted 28 May 2024 - 01:09 AM

Once you stack in siril, do a pcc color correction and then use starnet++ via siril integration to remove your stars so that you can process your nebula and stars separately.

 

Download the cli version of starnet and setup siril to use it directly via the star processing menu in siril


  • Mikeiss likes this

#8 Mikeiss

Mikeiss

    Viking 1

  • *****
  • topic starter
  • Posts: 517
  • Joined: 15 Sep 2012
  • Loc: Tucson

Posted 28 May 2024 - 01:58 AM

Once you stack in siril, do a pcc color correction and then use starnet++ via siril integration to remove your stars so that you can process your nebula and stars separately.

 

Download the cli version of starnet and setup siril to use it directly via the star processing menu in siril

I've already downloaded it. Just not quite comfortable yet with starless processing, practice makes perfect though. At least that's what they say.


  • Cryhavoc38 likes this

#9 Mikeiss

Mikeiss

    Viking 1

  • *****
  • topic starter
  • Posts: 517
  • Joined: 15 Sep 2012
  • Loc: Tucson

Posted 28 May 2024 - 02:14 AM

Let me just remind people that I asked which picture other people thought was best. I didn't exactly ask for constructive criticism or to be told how inferior my filter is. Let me just say that I can completely understand why some people get frustrated  and don't bother with this website.  Thanks



#10 smiller

smiller

    Gemini

  • *****
  • Posts: 3,330
  • Joined: 27 Oct 2018
  • Loc: Vancouver Washington (not BC!)

Posted 28 May 2024 - 08:42 AM

Filter never adds, only subtracts, you gain nothing from a non-narrowband filter.

 

Narrowband filters work but only because of the narrow part and the narrower the better.  These broad-filters that promise magic are just glass beads.

 

 

I use the filter for light pollution and it does that fairly well. It's not like I said "look how much better this is with the filter." And I like it which is what matters.  Good day

Nice comparison, thanks for sharing.

 

Perhaps what licho52 was trying to communicate was that if M17 is almost entirely an emission nebula then the narrower the filter the better and so an even greater difference in your imaging productivity could be had with an even narrower dual band filter.

 

But, with those you usually lose the SII, Hb, and some or all of the Oiiib and Nii, so this may be very target, imaging goal, and sky darkness related.  Also, some of the narrower filters pass less of the primary narrow bands (85-90%) instead of the ~96-98% (according to one tested filter) of your filter.   So I would say that for OSC filters although narrower is generally better on emission targets, general answers on the optimum choice can be complicated and it’s a topic that is regularly debated.


Edited by smiller, 28 May 2024 - 09:05 AM.


#11 Cryhavoc38

Cryhavoc38

    Ranger 4

  • *****
  • Posts: 331
  • Joined: 06 Jan 2023
  • Loc: Woodinville, WA

Posted 28 May 2024 - 02:11 PM

Since you asked, and because I use the antlia tri band alot, I am going to say that the first two look nearly the same and the 2nd and 3rd image are really wanting to be processed to get the color brought out of the nebulosity. 

 

The stars are monochromatic because it appears you processed the entire image the same, whereas the stars really benefit from an initial photometric color calibration and asihn stretch to preserve their true color. 

 

Practice does indeed make better, but please practice by separating your stars from the main dso object and recombine them all once you are satisfied with the dso processing.




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





Also tagged with one or more of these keywords: Astrophotography, CMOS, Imaging, Reflector



Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics