Do dark and flat frame work during live stacking?

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ippiu
Posts: 21
Joined: Fri Jul 06, 2018 7:02 pm

Re: Do dark and flat frame work during live stacking?

Post by ippiu » Fri Mar 08, 2019 4:15 pm

BlackWikkett wrote:
Fri Mar 08, 2019 1:39 pm
Seeing the initial dark frame I recognized this as a ASI294 and taking a cursory look at the log file this is confirmed. Normally the amp glow starburst pattern is seen in the upper right hand hand side of the frame. In the example provided the main amp glow starburst is in the lower left side and a minor amp glow is in the lower right. This looks to me as the image is flipped in both horizontal and vertical orientation so the amp glow appears in the lower left side of frame.
Yes, you are right, it's ASI294 Pro, cooled to -15 °C. Image is usually flipped both horizontally and vertically because i like to see things as they appear really in the sky to our eyes...
BlackWikkett wrote:
Fri Mar 08, 2019 1:39 pm
Since there's also some amp glow in the lower right could you have clicked the flip button while you were exposing the the dark frame?
No, absolutely i'm sure, no.
BlackWikkett wrote:
Fri Mar 08, 2019 1:39 pm
My experience with the 294 and using dark frames in live stacking you need to be very careful to apply the exact settings you will be using to capture your light frames. Exposure, gain, brightness need to be exact. Also recommend using the lowest brightness setting you can.
I take so carefully my darks, matching perfectly the temperature (i took different darks for 5 °C changing, so i'm very careful in taking darks), the exposure, gain. But brightness? Yes, there is a brightness slider, but just for pure visualization on the pc screen. I always know that this brightness slider deals only with screen brightness, just for seeing better the live view of the image. It isn't an inside camera parameter as gain, to deal and play with. So I left always brightness to 20 i think. Never considered as a real parameter...So what do you mean as "using the lowest brightness setting you can"?
BlackWikkett wrote:
Fri Mar 08, 2019 1:39 pm
For flats make sure you are using mono and and bias. With my light panel and scope (RC6) I usually use 300 gain, 200+ ms exp, brightness 0 and shoot 50 frames to create the master flat.
For flats, as almost everybody indicates, i use the lowest gain, in my case i use unity gain, that is 120. Set the flat box light to match the histogram around 45-48 % matching around 30.000 ADU (you can read the ADU in live histogram), for a 2s exp. I take 20 flats. I read many hours on forum about the correct flat exposure and i also tried many different exposure, from 0,5s to 4s: nothing changed.
BlackWikkett wrote:
Fri Mar 08, 2019 1:39 pm
Have a look at this viewtopic.php?f=5&t=1282 we worked this out a few months ago and this has been working very well.
I already had read this topic 2 weeks ago, when i was finding info about taking correct flats...

As i already told before, with SC 3.1 i didn't have these problems with dark and flat applying during live stacking, with the same equipment, same ways of taking darks and flats, same flip image, etc....

Thanks for trying to find a solution for my problem.

BlackWikkett
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Re: Do dark and flat frame work during live stacking?

Post by BlackWikkett » Fri Mar 08, 2019 11:42 pm

The "Brightness" control listed in SC if you are using the native driver is very much a live parameter that can have a significant impact on images. Other camera manufactures call this control "offset." While creating flats I've found it best to use brightness (offset) level of zero. While capturing live stacks i use the brightness control to move the histogram away from the left edge. This usually ends up being 3-5 brightness for my capture settings. I also use the same brightness setting for capturing the dark master.

Have a look at this topic viewtopic.php?f=9&t=1209

Here's an example of live stack including dark and flat master applied. Saved as an 8 bit png from SC then a color balance and noise reduction in Photoshop. If you follow the link to flickr you'll see the SC image capture settings.
ImageM13 Globular Cluster PS Edit Stack_65frames_3900s_WithDisplayStretch by Black Wikkett, on Flickr

Hope you get it working.

ippiu
Posts: 21
Joined: Fri Jul 06, 2018 7:02 pm

Re: Do dark and flat frame work during live stacking?

Post by ippiu » Sat Mar 09, 2019 7:55 am

BlackWikkett wrote:
Fri Mar 08, 2019 11:42 pm
The "Brightness" control listed in SC if you are using the native driver is very much a live parameter that can have a significant impact on images.
If it's just a live parameter (as i already understood) it shouldn't be so important for final image saved, or for live image stacked saved with adjustments. it's just a way of visualization the live image. Instead you're saying the opposite, that is important. Why?
BlackWikkett wrote:
Fri Mar 08, 2019 11:42 pm
While capturing live stacks i use the brightness control to move the histogram away from the left edge. This usually ends up being 3-5 brightness for my capture settings. I also use the same brightness setting for capturing the dark master.
If you will save the final stacked image with adjustments the brightness does not matter. If you intend to save the image "as seen", so the brightness plays an important role in the final stacked image. I usually don't save "as seen", but "with adjustments" so the brightness hasn't an impact on it.

So, i understand that it's better to use brightness 3-5, regardless about how i will save the final stacked image, right?

Robin, maybe you lost my previous answer where i asked you a question about the right image format to use for the images you need...If you could answer, so i'm sure on what to do.
Thanks

BlackWikkett
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Re: Do dark and flat frame work during live stacking?

Post by BlackWikkett » Sat Mar 09, 2019 3:59 pm

Brightness (offset), White Bal (R), White Bal (B), are controls in SC that for the ASI cameras effect the signal from the camera directly. These work on the data from the camera before any image adjustment is applied in SC.

poolemarkw
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Joined: Mon Mar 26, 2018 5:49 pm
Location: Indialanatic, FL

Re: Do dark and flat frame work during live stacking?

Post by poolemarkw » Mon Mar 11, 2019 5:26 pm

This made me wonder if I have an issue related to dark frames...Do they have to be taken at the same orientation (flip = none, etc...) as the light frames? I created a Dark Library but have no idea if I had the Flip set to something other than "None".

BlackWikkett
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Re: Do dark and flat frame work during live stacking?

Post by BlackWikkett » Mon Mar 11, 2019 5:58 pm

poolemarkw wrote:
Mon Mar 11, 2019 5:26 pm
This made me wonder if I have an issue related to dark frames...Do they have to be taken at the same orientation (flip = none, etc...) as the light frames? I created a Dark Library but have no idea if I had the Flip set to something other than "None".
Orientation has to be the same as the light frames.

poolemarkw
Posts: 54
Joined: Mon Mar 26, 2018 5:49 pm
Location: Indialanatic, FL

Re: Do dark and flat frame work during live stacking?

Post by poolemarkw » Mon Mar 11, 2019 6:47 pm

Thanks....so is there any way to know what orientation I used to create my darks?

poolemarkw
Posts: 54
Joined: Mon Mar 26, 2018 5:49 pm
Location: Indialanatic, FL

Re: Do dark and flat frame work during live stacking?

Post by poolemarkw » Mon Mar 11, 2019 6:58 pm

Just had another thought....If its true that the orientation (flip or not) of the darks and flats must match the lights, then we would need to have two different orientations of these any time that you do image acquisition that involves a Meridian flip. Correct?

Mark

BlackWikkett
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Re: Do dark and flat frame work during live stacking?

Post by BlackWikkett » Tue Mar 12, 2019 3:35 am

From my experience you image to the meridian or past it if you mount allows it (in my case I go 10 deg past before flip) If you're live stacking, once you do a flip you need to start over since the images will no longer align. If you're doing imaging this is less of a problem since you apply the flip to your raw data then stack

ippiu
Posts: 21
Joined: Fri Jul 06, 2018 7:02 pm

Re: Do dark and flat frame work during live stacking?

Post by ippiu » Tue Mar 12, 2019 7:55 am

Probably this njght i will do another test and i will post the results and all images robin asked to me.
But a question: is better to use rgb24 and save in .fit? Or raw16 and .fit? Or raw16 and .png? Or rgb24 and .png? I usually use raw16 and .png.

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