M27 in LRGB + SHO (Dumbbell)


ap@CaptivePhotons.com
 

While I'm here posting, here is one I put up yesterday and welcome suggestions and criticism. 

Full size here:  https://www.astrobin.com/92m59x/

All credit to the AP1100AE for the round stars of course.

I love getting data across all filters, it shows so much hidden detail viewed separately; I absolutely HATE trying to turn it into images. Picking colors, blending colors just drives me insane.  After a while I become a sort of color blind zombie just trying pallets at random.  This was after taking a day off and changing approaches. 

There is about 18 hours of data at 2800mm/F10 through all 7 filters (no luminance).  The stars are RGB only, the red on the bright part of the nebula comes mostly from the RGB (blended after stretching with square of value), and the halo and blue/cyan mostly from the NB colors, which were combined in a ForaxX type formula.  I first tried blending Red + Sii, Green + Ha, etc. but that did not work well, so I built the BB and NB images separately and combined.  I'm still not happy with the powder blue color but making it darker or more saturated just seemed to make it worse.   I'm even more unhappy with the dark part of the background which is blotchy from combing narrow and broad band backgrounds, but attempts to fix it made star replacement look even more strange. 

As I said, criticism and suggestions more than welcome, here or on Astrobin. 

Linwood


Mike Dodd
 

On 7/4/2022 12:38 PM, ap@... wrote:
While I'm here posting, here is one I put up yesterday and welcome suggestions and criticism.
Full size here: https://www.astrobin.com/92m59x/ <https://www.astrobin.com/92m59x/>
Very nice, Linwood. I'm glad you went very deep to capture the faint extended nebulosity. That's my goal for M27, but it's so small with my current OTA and camera, I'm not sure what would show up.

Great job!

--- Mike


Roland Christen
 

Pretty nice result. No criticism from me.

Do you find the C11 to need a lot of focusing with temperature change? It would seem to me that would be the case since the tube is aluminum and the optics are normal glass, not quartz or zero expansion materials. Maybe where you are in Florida the temps are pretty stable?

Rolando

-----Original Message-----
From: ap@... <ap@...>
To: main@ap-gto.groups.io
Sent: Mon, Jul 4, 2022 11:38 am
Subject: [ap-gto] M27 in LRGB + SHO (Dumbbell)

While I'm here posting, here is one I put up yesterday and welcome suggestions and criticism. 

Full size here:  https://www.astrobin.com/92m59x/

All credit to the AP1100AE for the round stars of course.

I love getting data across all filters, it shows so much hidden detail viewed separately; I absolutely HATE trying to turn it into images. Picking colors, blending colors just drives me insane.  After a while I become a sort of color blind zombie just trying pallets at random.  This was after taking a day off and changing approaches. 

There is about 18 hours of data at 2800mm/F10 through all 7 filters (no luminance).  The stars are RGB only, the red on the bright part of the nebula comes mostly from the RGB (blended after stretching with square of value), and the halo and blue/cyan mostly from the NB colors, which were combined in a ForaxX type formula.  I first tried blending Red + Sii, Green + Ha, etc. but that did not work well, so I built the BB and NB images separately and combined.  I'm still not happy with the powder blue color but making it darker or more saturated just seemed to make it worse.   I'm even more unhappy with the dark part of the background which is blotchy from combing narrow and broad band backgrounds, but attempts to fix it made star replacement look even more strange. 

As I said, criticism and suggestions more than welcome, here or on Astrobin. 

Linwood


--
Roland Christen
Astro-Physics


ap@CaptivePhotons.com
 

On Mon, Jul 4, 2022 at 02:30 PM, Roland Christen wrote:
Do you find the C11 to need a lot of focusing with temperature change? It would seem to me that would be the case since the tube is aluminum and the optics are normal glass, not quartz or zero expansion materials. Maybe where you are in Florida the temps are pretty stable?
Depends on what "a lot" is.  The worst part is early.  I set up just before sunset - earlier and it heats up too much from the sun, later and the mosquitos get too much blood.  This means it goes from a 74F house to maybe 85F ambient, then just as the glass is heating the ambient falls back to around 75F.  By 10pm+/- ambient stops changing fast and at a guess an hour or so later the OTA is probably more stable. Maybe, I do not know for sure. Maybe the vents on the edge help. 

I've tried refocusing based on temperature with zero success, really negative success.  Tracking trend lines they would reverse from one night to the next (probably related to what exact thing I measure).  Perhaps if there was a temp probe on the mirror back.  Now I focus every 45 minutes whether I need to or not, with a safety net checking HFR increase.  Works well.  I probably could change that to 45 minutes for the first few hours, then rarely, but that is inconvenient to program in NINA so I just keep going every 45 minutes. 

I added a Litecrawler.  While it has a lot of benefits, focusing faster (I'd say 50-60% of prior total time) makes focusing more often less costly.  Plus I can now change filters (with filter offsets) while guiding and not have to stop/start due to image shift. 

So short version is: Focus fast, focus often, and I don't think about it too hard.  And Nite/Litecrawlers are great! 

Linwood


Karen Christen
 

Dang, Linwood.  That’s really striking.  Great work.

Karen

AP

 

From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of ap@...
Sent: Monday, July 4, 2022 11:39 AM
To: main@ap-gto.groups.io
Subject: [ap-gto] M27 in LRGB + SHO (Dumbbell)

 

While I'm here posting, here is one I put up yesterday and welcome suggestions and criticism. 

Full size here:  https://www.astrobin.com/92m59x/

All credit to the AP1100AE for the round stars of course.

I love getting data across all filters, it shows so much hidden detail viewed separately; I absolutely HATE trying to turn it into images. Picking colors, blending colors just drives me insane.  After a while I become a sort of color blind zombie just trying pallets at random.  This was after taking a day off and changing approaches. 

There is about 18 hours of data at 2800mm/F10 through all 7 filters (no luminance).  The stars are RGB only, the red on the bright part of the nebula comes mostly from the RGB (blended after stretching with square of value), and the halo and blue/cyan mostly from the NB colors, which were combined in a ForaxX type formula.  I first tried blending Red + Sii, Green + Ha, etc. but that did not work well, so I built the BB and NB images separately and combined.  I'm still not happy with the powder blue color but making it darker or more saturated just seemed to make it worse.   I'm even more unhappy with the dark part of the background which is blotchy from combing narrow and broad band backgrounds, but attempts to fix it made star replacement look even more strange. 

As I said, criticism and suggestions more than welcome, here or on Astrobin. 

Linwood


--
Karen Christen
Astro-Physics