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My eaa screen shot of pillars of creation

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#1 GSBass

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Posted 16 July 2021 - 01:40 PM

I ended up letting this run for 3 hours and spent sometime learning editing this morning, I’m not sure what was up with the green artifacts in the middle of the image,  I was able to edit them out but thought it was a little weird…. Anyway I was using 11.5 seconds and about 85 gain… it was fun

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#2 Forward Scatter

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Posted 16 July 2021 - 02:08 PM

Way cool!


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#3 Medic002

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Posted 16 July 2021 - 02:13 PM

nice pics


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#4 alphatripleplus

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Posted 16 July 2021 - 02:17 PM

Was this taken with your 102EDL and the 462C camera?



#5 GSBass

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Posted 16 July 2021 - 02:27 PM

Yes, the processed versions are over at the beginners forum…. Was having trouble with my 485 so just used the 462c… it did well…. Just a small FOV

Was this taken with your 102EDL and the 462C camera?


Edited by GSBass, 16 July 2021 - 02:28 PM.

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#6 Clouzot

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Posted 16 July 2021 - 03:02 PM

Nicely done, and good resolution! As for the greenish gremlins, maybe wandering hot pixels? A slight color imbalance (here, green) and high saturation are often quite unforgiving

colorimb.png


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#7 GSBass

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Posted 16 July 2021 - 03:25 PM

Thanks…. I have not quite understood how the two histograms work…. I initial thought the main histogram in camera controls was basically the levels you were recording for a saved output to process later, An I thought the histogragm in live stacking just affected what you saw on the screen so you could enjoy watching the images come in…… but I noticed one was affecting the other last night so I’m a little confused….. need to read manual again or something

Nicely done, and good resolution! As for the greenish gremlins, maybe wandering hot pixels? A slight color imbalance (here, green) and high saturation are often quite unforgiving

attachicon.gifcolorimb.png



#8 alphatripleplus

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Posted 16 July 2021 - 05:42 PM

 As for the greenish gremlins, maybe wandering hot pixels?

That was my guess as well, assuming no guiding and some tracking error, resulting in  frame to frame movement of the hot pixels. 



#9 Clouzot

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Posted 16 July 2021 - 06:05 PM

Thanks…. I have not quite understood how the two histograms work…. I initial thought the main histogram in camera controls was basically the levels you were recording for a saved output to process later, An I thought the histogragm in live stacking just affected what you saw on the screen so you could enjoy watching the images come in…… but I noticed one was affecting the other last night so I’m a little confused….. need to read manual again or something

It's quite easy once you get the principle: what you see on the Livestack histogram (the large one) is the signal you captured and stacked, after color balancing but before stretching.

The curve you see in the so-called "mini display histogram" (the one on the right) is what is displayed on your screen, but with a twist: you can also stretch the mini histogram if you wish.

 

I usually work with both histograms in parallel: I wait for a couple images to be stacked, then I auto stretch the large livestack histogram (Sharpcap sets reasonable black-mid-white levels), then auto-stretch the mini histogram as well. The object should be popping on your screen as soon as you do that, albeit a bit too bright, usually. Then, just slide the mid level in mini histogram to the right until you get something you like.

 

You can see the livestack histogram as the first-line cleaner: removes the sky background and sets the mid (grey) level where it should be.

Then the mini histogram serves as a contrast setting: you can brighten the object without touching the rest.

 

The three color "spikes" (or, sometimes, "bumps", depends on multiple factors) are your sky background. As the sky is supposed to be color neutral, you want to align those three spikes together as closely as possible. It's sometimes not easy to achieve because the balance is highly sensitive and evolves as you stack more images. So make sure it's reasonably close, then focus on the small histogram on the right. There, you'll see your three bumps again, more or less aligned (depends on the stretch, and it'll be easier to fine tune things


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#10 GSBass

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Posted 16 July 2021 - 07:29 PM

Thank you so much for taking the time to explain….. if your main goal is to capture an image for post processing would your choices be the same? Obviously it’s very nice to have a good image on the screen while capturing…. I just want to ensure best data to work with afterwards also…. I actually used sharpcap save as seen several times but have not even looked at those yet…. It was a little overwhelming… played with the images probably 5 hours this morning

It's quite easy once you get the principle: what you see on the Livestack histogram (the large one) is the signal you captured and stacked, after color balancing but before stretching.

The curve you see in the so-called "mini display histogram" (the one on the right) is what is displayed on your screen, but with a twist: you can also stretch the mini histogram if you wish.

 

I usually work with both histograms in parallel: I wait for a couple images to be stacked, then I auto stretch the large livestack histogram (Sharpcap sets reasonable black-mid-white levels), then auto-stretch the mini histogram as well. The object should be popping on your screen as soon as you do that, albeit a bit too bright, usually. Then, just slide the mid level in mini histogram to the right until you get something you like.

 

You can see the livestack histogram as the first-line cleaner: removes the sky background and sets the mid (grey) level where it should be.

Then the mini histogram serves as a contrast setting: you can brighten the object without touching the rest.

 

The three color "spikes" (or, sometimes, "bumps", depends on multiple factors) are your sky background. As the sky is supposed to be color neutral, you want to align those three spikes together as closely as possible. It's sometimes not easy to achieve because the balance is highly sensitive and evolves as you stack more images. So make sure it's reasonably close, then focus on the small histogram on the right. There, you'll see your three bumps again, more or less aligned (depends on the stretch, and it'll be easier to fine tune things



#11 GSBass

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Posted 16 July 2021 - 07:38 PM

I just went and looked, here is one of the first ones I saved…. Thinking it was less than 30 minutes but had both histograms stretched, also you can see just the beginning of the green gremlin I experienced…. But still pretty cool it showed up this well in such a short amount of time, also the field rotation was just slight at this point… since I’m using a Az mount it is pretty severe once you  get past an hour or more and requires cropping 

It's quite easy once you get the principle: what you see on the Livestack histogram (the large one) is the signal you captured and stacked, after color balancing but before stretching.

The curve you see in the so-called "mini display histogram" (the one on the right) is what is displayed on your screen, but with a twist: you can also stretch the mini histogram if you wish.

 

I usually work with both histograms in parallel: I wait for a couple images to be stacked, then I auto stretch the large livestack histogram (Sharpcap sets reasonable black-mid-white levels), then auto-stretch the mini histogram as well. The object should be popping on your screen as soon as you do that, albeit a bit too bright, usually. Then, just slide the mid level in mini histogram to the right until you get something you like.

 

You can see the livestack histogram as the first-line cleaner: removes the sky background and sets the mid (grey) level where it should be.

Then the mini histogram serves as a contrast setting: you can brighten the object without touching the rest.

 

The three color "spikes" (or, sometimes, "bumps", depends on multiple factors) are your sky background. As the sky is supposed to be color neutral, you want to align those three spikes together as closely as possible. It's sometimes not easy to achieve because the balance is highly sensitive and evolves as you stack more images. So make sure it's reasonably close, then focus on the small histogram on the right. There, you'll see your three bumps again, more or less aligned (depends on the stretch, and it'll be easier to fine tune things

 

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#12 Clouzot

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Posted 17 July 2021 - 07:47 AM

Thank you so much for taking the time to explain….. if your main goal is to capture an image for post processing would your choices be the same?

Not always, but quite often, yes. Typical exposures in AP are way too long to my taste, but i also know that too short an exposure may be detrimental to my livestacks, so I try to balance things as far as possible.

 

Here's one lead, among others: there's that informal, fact-based rule in astrophoto called the three sigmas rule. It starts with an observation: your camera has some noise by construction (the level of which you can tell from the manufacture curves, for example). Then the rule goes like this: the faintest signal in all your images should always be at least 3 times higher than that camera noise. Most often, the faintest, useful signal is the sky background, because everything fainter that that will be lost anyway. These are your histogram "spikes", in fact.

 

Enter Sharpcap and its Smart Histogram, a very handy tool to ensure you follow the above rule: prior to the Livestack, just run your subexposures, with that smart tool open, and look for the colored bars on the top (red, orange, green). If you make sure your "spikes" belong to the green zone, then you're good to go, you're not losing anything. That's a good way to make sure than both your livestack and your possibly post-processed image will be OK.
 


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