Seeking Insight into PixInsight

[Scorpius]

I’ve downloaded the free trial of PixInsight & I'd really like to learn the workflow since it appears it should handle just about any processing task you could throw at it however, the phrase complexity of use is an understatement to say the least! Even so - it seems like I should at least be able to learn the basic integration/calibration/registration routines so hopefully someone will be so kind as to point out what I’m doing wrong in processing and/or data acquisition.

So cutting to the chase - I continue to have issues with a limited data set of M51 and I'm beginning to think it's more of a problem with the data than the software. Using PixInsight & trying to closely follow some online tutorials - When I try to calibrate the lights, I end up with almost completely dark images with only a few stars visible and can't get the galaxy to show up in PixInsight no matter what kind of stretching or intensity transformation I attempt to do. I suspect the darks and/or flats since I’m not even sure if I’m capturing them correctly but the bias appear to look like what would be expected.

I’m starting with integration of the bias (3) and darks (3) using the recommended settings and these are JPEG representations of what I’m getting. Of course I’m also getting pop-up’s that say the JPEG’s won’t be of the same quality as the Fits but hopefully they're good enough for someone to spot the problem...

Master Bias

Master Dark (screen shot captured from Photshop)

Master Dark (but looks like this in PixInsight)

Then I’m calibrating the flats (4-6) by doing the recommended subtractions first and then integrating them to create the master flat:

So far so good (except the master dark discrepancy between PS and PixInsight) but when I try to calibrate the lights (7) each one looks like this after running the calibration routine:

However the unprocessed luminance subs look like this so obviously the galaxy is there!

Even though I’ve never been able to get the luminance lights properly calibrated or integrated, I’ve managed the following just by fiddling around with the data in the various software programs I currently have and am still learning how to use. So if this is possible with convoluted, unconventional newbie processing methods, why is PixInsight giving me so much trouble when it’s supposed to be a one-stop solution for all things related to image processing?

If someone could please point out what I am doing wrong – I’d really appreciate the help... 

[davedownsouth]

Everything you need to know about PixInsight can be found here: -

http://www.harrysastroshed.com/pixinsight/pixinsight%20video%20html/Pixinsighthome.html

 Take the time to watch Harry's excellent video tutorials and you will learn everything you need to know 

[davedownsouth]

NB.  Forgot to say, your galaxy is there, it is just linear and all you need to do is push the auto stretch button to see it

[Scorpius]

NB.  Forgot to say, your galaxy is there, it is just linear and all you need to do is push the auto stretch button to see it

To be honest, didn't even know about the auto-stretch button til you mentioned it but unfortunately it didn't make the galaxy show on screen and neither did auto-stretch boost. Any other ideas?

Before auto-stretch

After auto-stretch

After auto-stretch boost

Still no galaxy "in sight"   (no pun intended) 

[Scorpius]

Apparently it's not about screen transformation anyway since this is the error message I get when attempting to register the calibrated luminance lights per the procedure outlined above. If all screen transformation does is change what it looks like on screen - but not the actual data- shouldn't PixInsight still be able to "see" enough stars to align the images even when they're not visible on-screen as long as they're part of the underlying data?

[lensman57]

Follow Harry's tutorials to get started. In fact those will do you until you get very advanced in your imaging. Learning the entire PI tools and how to use them with all the variables will take a lifetime and you also have to have a mathematician's brain and a good knowledge of software. Take your time with the tutorials and you should be fine, just one step at a time. BTW you need a pretty powerful computer for processing the subs from the larger CCDs and DSLRs. The stretched Dark frame you have posted shows a gradient that should not be there. Make sure that you take your darks with the camera off the scope and with cap fully tightened, if it is a DSLR make sure that there is no light leakage from the viewfinder and good luck.

A.G

[glowingturnip]

are you using the batch preprocessing script in Pixinsight to do it all in one go for you ?  Harry's tutorial for that here - http://www.harrysastroshed.com/pixinsight/pixinsight%20video%20files/pix%20videos/pixinsight%20cal%20mp4/pixinsight%20cal%20mp4.mp4

Your lights do actually look ok for an unstretched linear image, so I'm surprised you don't see more when you apply the autostretch tool - click the button with an icon that looks like a nuclear hazard warning.

is your bias that bright right off the camera, or have you applied a strong stretch to it ?  Obviously straight from camera it should appear virtually black.  Your calibrated flat looks very noisy, they wouldn't normally look noisy at all, which makes me suspect you're subtracting too much bias from it.

If you can, maybe upload a few of the raw files to dropbox and we can have a play around with them ?

ditto re the gradient on the dark, possibly light leaking in from somewhere

Cheers

[Scorpius]

Follow Harry's tutorials to get started. In fact those will do you until you get very advanced in your imaging. Learning the entire PI tools and how to use them with all the variables will take a lifetime and you also have to have a mathematician's brain and a good knowledge of software. Take your time with the tutorials and you should be fine, just one step at a time. BTW you need a pretty powerful computer for processing the subs from the larger CCDs and DSLRs. The stretched Dark frame you have posted shows a gradient that should not be there. Make sure that you take your darks with the camera off the scope and with cap fully tightened, if it is a DSLR make sure that there is no light leakage from the viewfinder and good luck.

 

A.G

Thanks A.G. - I appreciate the info. You're right, I need to go through the tutorials since there's just no shortcuts in this hobby. I did notice the gradient and know exactly where it came from. It's the opening in my filter wheel where you manually rotate the filters. I had waited til almost sunrise to start the darks trying to capture the most data I could but it ended up affecting the darks due to light leakage in the optical train. Guess I'll need to physically remove the camera next time and install the lens cap instead of relying on the scope cap to take the calibration frames. Probably will never completely learn PixInsight but would at least like to learn the basic pre-processing routines so I'll go through the tutorials step by step and take more care when capturing the calibration frames next time around...

Thanks again,

Scorpius

[MattJenko]

What you could do is try stacking without doing some of the calibration to identify the step which is blacking out your images.

You need to ensure all the images are aligned together which can be done using the StarAlign process on its own. Then you can use the resulting images to use ImageCalibration to do just flats, or just darks, or you could go straight to the ImageIntegration process to see if you get anything useful without any calibration at all.  You don't need to use the BatchPreProcessing script to trouble shoot,

Cheers

Matt

[Scorpius]

are you using the batch preprocessing script in Pixinsight to do it all in one go for you ?  Harry's tutorial for that here - http://www.harrysastroshed.com/pixinsight/pixinsight%20video%20files/pix%20videos/pixinsight%20cal%20mp4/pixinsight%20cal%20mp4.mp4

 

Your lights do actually look ok for an unstretched linear image, so I'm surprised you don't see more when you apply the autostretch tool - click the button with an icon that looks like a nuclear hazard warning.

 

is your bias that bright right off the camera, or have you applied a strong stretch to it ?  Obviously straight from camera it should appear virtually black.  Your calibrated flat looks very noisy, they wouldn't normally look noisy at all, which makes me suspect you're subtracting too much bias from it.

 

If you can, maybe upload a few of the raw files to dropbox and we can have a play around with them ?

 

ditto re the gradient on the dark, possibly light leaking in from somewhere

 

Cheers

Thanks for the response and it's obvious I need to read up on the proper methods for capturing calibration frames since they look so "out of whack" to the folks who actually know what they're doing Maybe this is just the natural progression for a newbie like me - finally beginning to capture the necessary amount of light frames but struggling to get the calibration frames needed to make the light frames look good. Might try posting some of them on dropbox but right now it's off to work to enjoy another wonderful Monday morning at the proverbial salt mine...

[Scorpius]

What you could do is try stacking without doing some of the calibration to identify the step which is blacking out your images.

 

You need to ensure all the images are aligned together which can be done using the StarAlign process on its own. Then you can use the resulting images to use ImageCalibration to do just flats, or just darks, or you could go straight to the ImageIntegration process to see if you get anything useful without any calibration at all.  You don't need to use the BatchPreProcessing script to trouble shoot,

 

Cheers

Matt

Thanks Matt - This sounds like a great idea. Maybe that way I can at least identify the issue so it can be addressed next time out...

Cheers!