My first Veil Nebula, and test of the L-Ultimate

[Smiller]

Since I shoot very short exposures with my basic Alt/Az Goto Dob, I wasn’t sure I’d see a big advantage with the Optolong-L Ultimate over my less aggressive IDAS NBZ.  But my first outing capturing about 3.5 hours of the Veil was a good sign that it’ll be a great addition.  Amazing using 6 second exposures with a 3nm bandpass filter.

Stats:

Scope: Orion XT12G 12" Alt/Az Goto Dob with Nexus 0.75x Reducer/Corrector (1125mm/f3.7)

Camera: ASI2400MC

Filter: Optolong L-Ultimate

Capture Stats:  about 1800 * 6 second exposures  (3 hours of exposures captured over about 3.5 hours)

Software:  SIRIL + Affinity Photo + Xterminators

Sky conditions: Bortle 6/7, partial moon

 

Edited June 14, 2023 by Smiller

[Phillyo]

It's bonkers you can get so much detail from just 6 second subs. It makes you wonder about the need for 5min or 10min subs. Great images, this and the crescent nebula are both gorgeous.

Phil

[scotty38]

18 minutes ago, Phillyo said:

It's bonkers you can get so much detail from just 6 second subs. It makes you wonder about the need for 5min or 10min subs. Great images, this and the crescent nebula are both gorgeous.

Phil

This is a great image but to answer your question on sub length then, for me at least, I would say storage and processing of 1800 subs would be the downside. I would still end up with 3 hours of data just fewer subs to deal with and yeah I get the issues of losing longer subs, the need for guiding etc etc so I'm only really comparing the pros and cons of sub length - if you see what I mean....

Edited June 14, 2023 by scotty38

[Jeff5567]

Cracking image!

[Phillyo]

50 minutes ago, scotty38 said:

This is a great image but to answer your question on sub length then, for me at least, I would say storage and processing of 1800 subs would be the downside. I would still end up with 3 hours of data just fewer subs to deal with and yeah I get the issues of losing longer subs, the need for guiding etc etc so I'm only really comparing the pros and cons of sub length - if you see what I mean....

Oh absolutely, total combined exposure time is key. I'd rather deal with fewer 5min subs than more 10 second subs for sure. Just impressive the level of detail collected from such short sub lengths.

[adyj1]

Very nice pic - best I've seen of the veil for a while. 

[Richard_]

Incredible image despite short exposure length and tracking. Well done! 

[Smiller]

5 hours ago, scotty38 said:

This is a great image but to answer your question on sub length then, for me at least, I would say storage and processing of 1800 subs would be the downside. I would still end up with 3 hours of data just fewer subs to deal with and yeah I get the issues of losing longer subs, the need for guiding etc etc so I'm only really comparing the pros and cons of sub length - if you see what I mean....

For sure the massive number of subs is a substantial downside.  If I could take 3 minute subs or even 30 second subs with my system I would in a heartbeat!   I’ve spent many hours testing the various stacking programs (and testing various parameters) to find the ones that have the best combination of speed and quality.  Thank goodness for SIRIL for its incredible speed, very high quality output, and the option for using RICE near lossless compression for the 32-bit intermediate results.  That combination is incredible.  Astro Pixel Processor  is much slower but very high quality especially if I need to protect dim nebulosity near the edge of the rotated field with its “multiband blending” feature which is unmatched.  DSS didn’t have quite the quality or robustness for me and PI was just too darn slow… way slow!   And PI’s output in my testing was nearly identical in quality to APP and SIRIL.

How fast is SIRIL?  I stacked the veil with SIRIL in 1 hour and 40 minutes.  For me that’s not really a problem.  With APP, it would take about 8 hours and with PI, it probably wouldn’t ever complete (I often have PI’s WBPP crash), but if it did it would be 16-24 hours or so.   If the world of AP only had PI, I wouldn’t be doing this.  This is on my 2 year old 8 core laptop… the latest desktops are 2.5-3x faster BTW.

For data storage, yeah, I have an internal 2TB SSD for active projects and two external 12TB disks to hold completed projects, one as a backup of the other.   With lossless 7z compression in fast mode (which is really quite fast) I can compress 2:1 and 12TB is enough for about 300 projects.   That will be years of projects at my rate.

 

Edited June 14, 2023 by Smiller

[Smiller]

1 hour ago, Richard_ said:

Incredible image despite short exposure length and tracking. Well done! 

I looked at your astrobin and you have a very similar Crescent!  Your Oiii filter allowed better Oiii, something I think my setup (dual narrowband) doesn’t do well as a lot of Ha leaks into the G and B channels and I think the software does a poor job of isolating it.

[Richard_]

6 hours ago, Smiller said:

I looked at your astrobin and you have a very similar Crescent!  Your Oiii filter allowed better Oiii, something I think my setup (dual narrowband) doesn’t do well as a lot of Ha leaks into the G and B channels and I think the software does a poor job of isolating it.

Thanks for checking out my astrobin! Yes, having a tighter bandpass on Oiii will yield you better quality data, but if you didn't notice from my image I had almost twice the Oiii data (4h45m) compared to my H-alpha data (2h35m). I bet if you had more Oiii data it would stand out a bit.

If I recall correctly, since I captured Oiii separately I could boost the histogram a little more than H-alpha before I merged them together. Careful application of colour masks later in the process flow would allow me to boost the saturation of Oiii to help make it pop! 

Did you process your image "as captured" or did you split out the RGB channels separately? I wonder if you could work on the G channel separately, ditch the Blue channel and then perform Channel Combination using Red channel as R, and Green channel as G and B (eg to make a HOO palette)? 

[Smiller]

2 hours ago, Richard_ said:

 

Did you process your image "as captured" or did you split out the RGB channels separately? I wonder if you could work on the G channel separately, ditch the Blue channel and then perform Channel Combination using Red channel as R, and Green channel as G and B (eg to make a HOO palette)? 

I processed it as a color image.  I did boost the blue channel a tad but didn’t really do any attempt extracting OIII.  Since the green channel of my cameras have 15% sensitivity to Ha so if the OIII signal is low it’s very difficult to extract the OIII without doing some fancy extraction based on the specific camera spectral absorption. I haven’t figured out how to do that yet.