Recent posts

#51

Astrophotography / Re: M51

Last post by JohnH - Apr 02, 2025, 11:19:13

Thanks Carole,

My working theory is that simply using a Dual Band filter for Luminance would mean that some areas with detail might be completely missing because there would only be data from the narrow Ha and OIII bands. That is why I have added an arbitrary 25% of my RGB data.

For chrominance I use RGB data and a "Photometric Continuum" subtracted Ha layer. Again, my working theory is that Blue/Green data will be picked out by the OIII Luminance and the Ha/Red data will be picked out by the Ha Luminance.

For both layers I use a Masked Stretch followed by a Generalised Hyperbolic Stretch to pull as much detail as possible. I the use the Pixinsight Multiscale Linear Transform process to further sharpen the Luminance layer.

Starexterminator then gives me the subject layer and star only layer which I process separately in Affinity Photo 2 before recombining.

Obviously, some or most of this may be wrong or unnecessary  but I think that my images are considerably improved.

#52

Astrophotography / Re: M51

Last post by Carole - Apr 01, 2025, 21:19:56

With the genuine tidal tails, and without the miscreant tidal tails.  Well done for your perseverance.  Nice image.  I'd be inclined to do a separate Crop as well. 

Can you explain what Chrominance is compared to Luminance and why you need both?

#53

Astrophotography / M51

Last post by JohnH - Apr 01, 2025, 19:02:11

A fairly wide field image of M51



Approximately 7 hours 30 mins of imaging.

Luminance HaO + R + G + B
Chrominance Ha + R + G + B

Sharpstar 15028 HNT 150mm f2.8
ZWO ASI1600MM Pro

#54

Astrophotography / Re: IC 443

Last post by Carole - Mar 28, 2025, 14:05:39

Yes, I always use a PNG on Astrobin. 

Just having try to post your image from Astrobin

#55

Astrophotography / Re: IC 443

Last post by JohnH - Mar 22, 2025, 10:54:44

(For some reason I cannot link to the TIFF file uploaded on Astrobin)

Were you trying to link it as an IMG or as a URL?

I copied the link from Astrobin and pasted it into "insert image". I noticed that the link includes "blob" in the URL which I don't recall seeing before.

Blob is database speak for binary large object, a way of storing pictures amongst other things.

You need to use the URL of a jpeg or PNG version of your image rather than TIF which browsers can't display. I've only dabbled in Astobin so not much help beyond that.

HTH Duncan

Thanks, that is useful to know.

#56

Astrophotography / Re: IC 443

Last post by The Thing - Mar 22, 2025, 10:49:08

(For some reason I cannot link to the TIFF file uploaded on Astrobin)

Were you trying to link it as an IMG or as a URL?

I copied the link from Astrobin and pasted it into "insert image". I noticed that the link includes "blob" in the URL which I don't recall seeing before.

Blob is database speak for binary large object, a way of storing pictures amongst other things.

You need to use the URL of a jpeg or PNG version of your image rather than TIF which browsers can't display. I've only dabbled in Astobin so not much help beyond that.

HTH Duncan

#57

Astrophotography / Re: IC 443

Last post by Rick - Mar 22, 2025, 09:50:18

I copied the link from Astrobin and pasted it into "insert image".

Might it, as an alternative, be worth just posting the URL of the Astrobin page?

#58

Astrophotography / Re: IC 443

Last post by JohnH - Mar 22, 2025, 08:17:07

(For some reason I cannot link to the TIFF file uploaded on Astrobin)

Were you trying to link it as an IMG or as a URL?

I copied the link from Astrobin and pasted it into "insert image". I noticed that the link includes "blob" in the URL which I don't recall seeing before.

#59

Astrophotography / Re: IC 443

Last post by Rick - Mar 21, 2025, 20:33:11

(For some reason I cannot link to the TIFF file uploaded on Astrobin)

Were you trying to link it as an IMG or as a URL?

#60

Astrophotography / Re: IC 443

Last post by Carole - Mar 21, 2025, 16:35:48

Hi John, I'll wait and see if you revise the stars before putting this on Members images. 

Nebulosity is good.  Can help wth Pixinsight or Affinity Photo - Sorry.