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Humidity?

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#1 M. Wood

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Posted 27 May 2024 - 12:36 AM

I think that when relative humidity is 75% or higher, my celestial photos have strange noise (?).  Any one know if this is caused by humidity or something else?  Thanks.

 

Tried to upload .pgn sub, but file was too large.


Edited by M. Wood, 27 May 2024 - 11:52 PM.


#2 Zambiadarkskies

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Posted 27 May 2024 - 12:50 AM

I think that when relative humidity is 75% or higher, my celestial photos have strange noise (?).  Any one know if this is caused by humidity or something else?  Thanks.

It would be helpful if you gave details - sub length, number of subs, camera settings, scope details.  Basically the more info you put in the better the help will be.  

 

I regularly image in Zambia's wetter seasons and have never noticed a correlation between noise and humidity.  


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#3 ayadai

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Posted 27 May 2024 - 07:42 AM

80% RH all of the time and no (unexpected) noise here. That goes for dedicated astro cameras as well as DSLRs. As Zambiadarkskies mentions, we also need more details, including what kind of camera you are using.


Edited by ayadai, 27 May 2024 - 07:44 AM.


#4 M. Wood

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Posted 27 May 2024 - 08:07 AM

Sub length is 4-15 seconds.  Number of subs is real time stacking in Sharp Cap Pro for 5-60 minutes.  Tried different scopes, including Celestron 70/900 refractor, Celestron 80/400 refractor, Bresser 102/460 refractor, Celestron 102/1000 refractor, Sky Watcher 120/600 refractor, Orion 130/650 Newtonian, Celestron 150/750 Newtonian and a 6" SCT.  No difference.  Cameras SvBony 305, SvBony 705c, SvBony 405cc.  No difference.  Tried Sky Watcher AZ GTi, Sky Watcher Star Adventurer mounts and a Celestron CG-4 mount with an installed Astro Gadget go to conversion kit.  No difference.

 

Location is a small town in South East Kansas, U.S.A.  Bortle 6 sky.  Street light at both ends of the block.  Tried ICE LiPo, SvBony UHC, SvBony CLS and SvBony 6mm dual band filters.  None helped.  Tried early and night, late at night and early in the morning.  Time irrelevant.

 

Have tried using both of my personal computers with 25' extension cables attached to the camera and both of my laptops next to telescope with no extension cable.

 

Started amature astronomy in August 2023.  Had never owned a telescope or camera before then.  Learned a lot reading this forum.  Never posted before, because I had nothing to contribute.

 

Always use darks and flats and have taken them dozens of times.  They make no difference.  Have tried not using them and got both vignetting and amp glow with the SvBony 405cc and dust motes with the SvBony 705c.

 

Had a wide variety of issues with telescopes, cameras, mounts, polar alignment and so forth and resolved all issues, except this one.

 

Problem began in March 2024.  Sometimes photos show rings radiating from brightest portion of image, such as the galaxy or star cluster.  It is not vignetting, however.  Sometimes photos show faint lateral lines.  Sometimes I get a rumpled off black color everywhere in the background.

 

I normally use the auto stretch in Sharp Cap.  I can work around these issues by moving the "Mid Level" in Sharp Cap live stack to the far right.  But, so doing makes the photo very dim.  Sometimes, the colors become very unstable and look crazy, even after a couple minutes of live stacking.  Changing cameras does not help.

 

I go out every night with clouds 20% or less and it is not raining of snowing.  This issue is different than telescope fogging over with dew.  I know that look and have purchased a couple dew heaters.  They do not help.

 

I do notice similar problems when the moon is out and over 50% or the moon is out and there is haze around it. 

 

I have noticed that since March, the humidity here has been 75% or higher most nights.  Could be coincidence.  But, I did not have this problem last winter.  So?



#5 Robert7980

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Posted 27 May 2024 - 09:02 AM

I see many different issues.

 

First with high levels of light pollution you need more intergration time that you are getting, 5 to 60 minutes isn’t nearly long enough. 
 

Second you will probably benefit from dithering your subs (slight movement of the target on the camera sensor so noise doesn’t build up). 
 

Your optics could use some attention, it looks like you have a large amount of tilt and uneven coma. 
 

High humidity usually only affects the fine resolution it has a tendency to blur things, or in very high humidity cause halos… 

I don’t really have any idea what’s causing that strange noise pattern, it looks like a lot of movement in the camera with rotation in the dark noise. It’s honestly pretty weird. I’d go back to basics and build your workflow up from scratch. There’s a lot of room for improvement if you get a basic foundation sorted out. 
 

My suspicion, without any real evidence is something is going badly wrong with your dark calibration or stacking… Only a guess, but I can’t really think of anything else, I’ve never seen anything exactly like that before. It’s more likely a combination on a few things not just one. Polar alignment would be high on my list to check with odd rotation in the field, but you didn’t run long enough for that to be an explanation so… not sure… 

 

We can rule out humidity though, that’s certain. 


Edited by Robert7980, 27 May 2024 - 09:08 AM.


#6 M. Wood

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Posted 27 May 2024 - 09:06 AM

I see many different issues.

I had no problem until March.  My photos came out quite nicely.



#7 Robert7980

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Posted 27 May 2024 - 09:21 AM

I had no problem until March.  My photos came out quite nicely.

What changed in March, I’d be trying to hunt that down. Where there any software updates? Things you started doing differently? 
 

Do you have any examples of a single sub you could share, that would tell a big part of the story. 



#8 M. Wood

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Posted 27 May 2024 - 09:38 AM

What changed in March, I’d be trying to hunt that down. Where there any software updates? Things you started doing differently? 
 

Do you have any examples of a single sub you could share, that would tell a big part of the story. 

Sort of glad it's not the humidity.  No software updates.  Made a lot of changes, trying everything I could think of to find problem. Nothing worked.  Can't dither.  I do not use guiding.  Never have.  I do not do post processing.  Never have.  I don't save single subs.  I just tell Sharp Cap to save exactly as seen when I am satisfied.  I will go out tonight (it is 9 am here) and save some subs.  Thanks.



#9 rj144

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Posted 27 May 2024 - 04:23 PM

I image the whole summer in South Florida where the humidity is constantly 80% or more at night and I never see anything weird with my pics.



#10 rj144

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Posted 27 May 2024 - 04:25 PM

Sub length is 4-15 seconds.  Number of subs is real time stacking in Sharp Cap Pro for 5-60 minutes.  Tried different scopes, including Celestron 70/900 refractor, Celestron 80/400 refractor, Bresser 102/460 refractor, Celestron 102/1000 refractor, Sky Watcher 120/600 refractor, Orion 130/650 Newtonian, Celestron 150/750 Newtonian and a 6" SCT.  No difference.  Cameras SvBony 305, SvBony 705c, SvBony 405cc.  No difference.  Tried Sky Watcher AZ GTi, Sky Watcher Star Adventurer mounts and a Celestron CG-4 mount with an installed Astro Gadget go to conversion kit.  No difference.

 

Location is a small town in South East Kansas, U.S.A.  Bortle 6 sky.  Street light at both ends of the block.  Tried ICE LiPo, SvBony UHC, SvBony CLS and SvBony 6mm dual band filters.  None helped.  Tried early and night, late at night and early in the morning.  Time irrelevant.

 

Have tried using both of my personal computers with 25' extension cables attached to the camera and both of my laptops next to telescope with no extension cable.

 

Started amature astronomy in August 2023.  Had never owned a telescope or camera before then.  Learned a lot reading this forum.  Never posted before, because I had nothing to contribute.

 

Always use darks and flats and have taken them dozens of times.  They make no difference.  Have tried not using them and got both vignetting and amp glow with the SvBony 405cc and dust motes with the SvBony 705c.

 

Had a wide variety of issues with telescopes, cameras, mounts, polar alignment and so forth and resolved all issues, except this one.

 

Problem began in March 2024.  Sometimes photos show rings radiating from brightest portion of image, such as the galaxy or star cluster.  It is not vignetting, however.  Sometimes photos show faint lateral lines.  Sometimes I get a rumpled off black color everywhere in the background.

 

I normally use the auto stretch in Sharp Cap.  I can work around these issues by moving the "Mid Level" in Sharp Cap live stack to the far right.  But, so doing makes the photo very dim.  Sometimes, the colors become very unstable and look crazy, even after a couple minutes of live stacking.  Changing cameras does not help.

 

I go out every night with clouds 20% or less and it is not raining of snowing.  This issue is different than telescope fogging over with dew.  I know that look and have purchased a couple dew heaters.  They do not help.

 

I do notice similar problems when the moon is out and over 50% or the moon is out and there is haze around it. 

 

I have noticed that since March, the humidity here has been 75% or higher most nights.  Could be coincidence.  But, I did not have this problem last winter.  So?

What are the details for this particular pic though?  You give a range of subs, integration times, and equipment.



#11 ayadai

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Posted 27 May 2024 - 05:07 PM

I notice that all of your cameras are SVBony; have you tried updating drivers and/or firmware? It sounds like you're essentially doing EAA in Sharpcap and saving a session image. You may wish to alter your workflow as a workaround, saving subs and calibration frames and processing in Siril.


Edited by ayadai, 27 May 2024 - 05:09 PM.


#12 M. Wood

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Posted 27 May 2024 - 11:39 PM

I notice that all of your cameras are SVBony; have you tried updating drivers and/or firmware? It sounds like you're essentially doing EAA in Sharpcap and saving a session image. You may wish to alter your workflow as a workaround, saving subs and calibration frames and processing in Siril.

They worked fine until march.  Have latest drivers. Could try altering workflow.  Would rather solve problem. 



#13 M. Wood

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Posted 29 May 2024 - 05:43 PM

What changed in March, I’d be trying to hunt that down.

Well, I just found out the oil refinery 1.25 miles Northeast of my house cranked up to full production in March.  Could that have made a difference?



#14 Robert7980

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Posted 29 May 2024 - 07:52 PM

Well, I just found out the oil refinery 1.25 miles Northeast of my house cranked up to full production in March.  Could that have made a difference?

That’s dang close brother, I feel for you. I lived in Corpus Christi many years ago and 18 miles was close enough for me. Anything is possible. The refineries are usually distilling and cracking hydrocarbons, that doesn’t normally result in significant emissions, I doubt a flare stack would have much effect unless it’s very bright or they are burning off a fraction that has high soot (black smoke), maybe I guess… 




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