Live Stack with Flat Frame Bug?

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BlackWikkett
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Re: Live Stack with Flat Frame Bug?

#71

Post by BlackWikkett »

Sorry Robin, I don't have the raw frames available. I've had such good success with live stacking just found I wasn't doing anything with the raw frames. I can test this the next time I have clear skies. I'll use v6128 to make a flat then live stack an object saving the raw frames. Then use the raw frames and flat in v6194 to make a new stack. That the captured data is different I find hard to believe since during testing once I had the initial result the scope stayed on the object and just cleared live stack and changed flat it was using.

This makes me wonder if the Dark may have something to do with it since the dark was made in v6128 at the end of 2019 and was a 50 frame master dark. Thoughts?

Looking at the forecast may have some clear skies later this week

-Chris
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Re: Live Stack with Flat Frame Bug?

#72

Post by admin »

Hi Chris,

probably worth making an updated dark with 6194, just in case something has changed at the camera SDK side - all of the major manufacturers did SDK updates between 6128 and 6194, and you never know what goes into them!

cheers,

Robin
BlackWikkett
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Re: Live Stack with Flat Frame Bug?

#73

Post by BlackWikkett »

Hi Robin,

As I post this I'm capturing some live stacks on NSN. Looks like making new darks in v6194 along with new flat in v6194 was the secret sauce. This seems to have fixed the issue. I'll keep you posted if i encounter any other issues! Thanks for your assistance.

-Chris
GaryS
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Re: Live Stack with Flat Frame Bug?

#74

Post by GaryS »

Hi All, I’ve read through the 8 screens of this topic and I’m wondering whether it’s possible yet to take a stab at summarizing what seems to work best for capturing Flats. I’m sorry but I’m not as experienced as all of you and I just created my first Flats on my uncooled 294 based on a variety of info here, in the SC manual and on the CN forum. They did nothing to fix my vignetting so I’m hoping for guidance from the SC brain trust in this thread. Could someone take a minute and summarize the current best thinking on how to capture Flats? Also, one more question...what is meant by the “offset %’s” that appeared in the suffix of the flats I captured? Black wicket tried explaining but I still don’t know what it is or what, if anything, I need to do about these ‘offsets’. Are they covered elsewhere in these forums or in the SC manual? Sorry to be still so far down the learning curve on SC after 9 (!) months trying to learn...

Very much appreciated!
BlackWikkett
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Re: Live Stack with Flat Frame Bug?

#75

Post by BlackWikkett »

Hi GaryS

I'll try to explain the process I use that I've found success with using flat and dark for Live Stacking.

The "offset=" suffix in flats don't worry about it. This is used internal by SC. Long story short = ignore this!

I'm assuming you have some way to illuminate your camera while attached to the telescope to create a flat. You have installed the latest version of SharpCap, at the time of posting 1-24-20 version 3.2.6194. You have the latest drivers installed for your ZWO Cameras version 3.0.0.7. When you connect to the camera via SharpCap you select the camera by name in the cameras drop list (as apposed to connecting via ASCOM.)

Darks:
1. Set exposure, gain, brightness, White Bal (R) and White Bal (B) the same as you will use for capturing you light frames. look at image controls for the white balance and brightness settings
sc-image controls.PNG
sc-image controls.PNG (37 KiB) Viewed 2464 times
2. From capture menu select Capture Dark Frame, settings minimum 10 and select Dark Library. This will save the master dark in your SharpCap save location the "dark" folder. Default location is desktop
sc-capture dark frame.PNG
sc-capture dark frame.PNG (16.12 KiB) Viewed 2464 times


Flats:
NOTE: I'm providing what I use for my ZWO ASI294MC Pro. Since you have a non cooled version you may have to play with this but it should work just fine.

1. Setup your scope with your illumination for flats
2. Gain 300, Brightness 0, While Bal (R) 50, White Bal (B) 50 (depending on how bright your flat light source is you'll have to play with gain but keep the other settings as provided)
3 turn on Histogram, this will open the large histogram at just below the main image.
sc-histogram.png
sc-histogram.png (12.26 KiB) Viewed 2464 times
Continued in next post, reached image limit
BlackWikkett
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Re: Live Stack with Flat Frame Bug?

#76

Post by BlackWikkett »

Flats continued

4. Adjust the exposure time (for my flats light source and gain 300 220ms -230ms) You'll need to adjust based on your light source to get similar histogram. I'm using a simulated image here but it will look something like this. If you have filters in the image train this will also change your histogram. You want the white channel around 50% the highest no higher than 100%, avoid saturation. The lowest in this case red no lower than 20%
sc-histogram example.png
sc-histogram example.png (24.9 KiB) Viewed 2463 times
5. Once happy with the histogram select capture flat frame from the capture menu. Number of frames I use 50 and check marks in Capture and subtract bias frame and create monochrome flat frame. Before you click start you'll want to give the flat a name that makes sense to you. In may case my naming convention is FLAT-224-BIAS-MONO (224 refers to exposure time) If you have the default settings in SharpCap for saving files this will be saved in the SharpCap folder on your desktop in date of creation then the folder with the name you provided.
sc-capture flat frame.PNG
sc-capture flat frame.PNG (20.51 KiB) Viewed 2463 times
Now just need to apply the dark and flat in Live stacking. This is in the preprocessing section
sc-preprocessing.PNG
sc-preprocessing.PNG (50.46 KiB) Viewed 2463 times

Hope this is helpful! If you'd like to see SharpCap in action you can fined many folks using SC and broadcasting here https://www.nightskiesnetwork.com/ you can sign up for free account to interact with broadcasters and viewers.

-Chris
GaryS
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Location: Boston, USA/Jackson Hole, USA

Re: Live Stack with Flat Frame Bug?

#77

Post by GaryS »

Ok Chris, that’s a big help- thank you! I have followed many of the same instructions when I just tried creating Flats except:
- used 0 gain
- used daylight and a pillowcase ( do I need the luminous panel?)
- did 40 frames
- created separate flats for filter and no filter conditions
- didn’t apply a Dark when I tested the flats on various Orion area nebulae.

Regarding Darks, I was planning to create a small test library based on the following:
- exposure settings of 8, 12 and 15 secs
- gain settings of 200, 300 and 400
- I’ll used the brightness at 10, White (R) (B) at 50 as you indicated
- I’ll arrange the above in a matrix that combines the higher gain with lower exposures and vice versa so I get darks that generally make sense.....does this make sense?

I have joined in NSN many times to watch but am unable to ever hear any dialog so I miss out on whatever might be being said about what’s going on and why. I tried asking a written question once but no one answered so I assumed that the text box wasn’t working as well as the audio. Do you think the creator of the site will ever get those features working? It would be terrific learning experience.

Thank you again for taking the time to write up your guidance...
Cheers
Gary
donboy
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Re: Live Stack with Flat Frame Bug?

#78

Post by donboy »

Gary,

I'm going to chime in here and give you a link that will set you up with hearing and chatting capability on NSN.

If you install UC browser that will work or

If you install an older version of Chrome called Chromium Portable. Here is a link thru CN that will direct you depending on your OS.
https://www.cloudynights.com/topic/6447 ... &p=9203044

Don
GaryS
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Re: Live Stack with Flat Frame Bug?

#79

Post by GaryS »

Thank you Don...
BlackWikkett
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Re: Live Stack with Flat Frame Bug?

#80

Post by BlackWikkett »

@GaryS

Your darks strategy is more or less what I do. For darks it's very important your brightness, Red and Blue white balance is the same as what you intend to image with.

For flats on a CMOS camera never use 0 gain. At a minimum I would never go below unity gain (117 and 120 for HCG mode) I use the same gain I generally image at which is 300 gain. The higher gain allows for very short exposures. For flats rule of thumb is no more than 2 second exposures. You're using daylight flats which is fine. Problem is that at night when temperatures are lower you're bound to have a focus shift which can invalidate the flat since you'll have to refocus. Get a cheapo tracing tablet from Amazon $20 USD. I use this at it lowest brightness level and diffuse through a T-shirt. I make my flat after I setup for the night once I've verified focus.

Once on NSN and you'll want to follow the link Don provided to setup a browser that's working for the site. If you type a text message and you get no reply just keep at it and you may also have to refresh the browser. Some of the Broadcasters only have one screen and depend on voice comms for audience interaction.

-Chris
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