20 replies to this topic

[ronrrm]

So, I bought an astro cam (SV705C - OSC), because I couldn't get my Nikon to play nice with SharpCap.  Then rather than sticking with SharpCap the other night, I decided to give Nina a try with the SV705c.

 

I chose TIFF output, never gave it another thought...all the TIFF's are grey scale.

 

DSS shows them as grey scale, tried selecting different debayering in DSS...same results, grey scale.

 

Couple of questions -

 

my tiff actually grey scale?...oh well, lesson learned if that's the case...back to SharpCap or use FITS out of NINA.

can the tiff's possibly contain color just are not debayered?

Is NINA able to output debayered TIFFs

 

Ron

[idclimber]

Tiff or fits is just the container for the data. It will not be color until the integration is debayered. If you link the file I or others will be glad to open and inspect it. 

[bobzeq25]

 

can the tiff's possibly contain color just are not debayered?

Is NINA able to output debayered TIFFs

 

 

That's exactly what's happening.  ANY images from color cameras are grayscale until they get debayered.

 

BUT, you need to do that at the right point in the process.  That's not in data acquisition (so you don't want NINA to debayer them), it's down the line in processing.

 

Starting with the greyscale frames from the camera.

 

You stack the bias into a master bias. 

 

You calibrate the flats with the master bias.

 

You stack the calibrated flats into a master flat.

 

You stack the darks into a master dark.

 

You calibrate the lights with the three masters. 

 

THEN you debayer the calibrated lights.

 

Then you align the debayered lights.

 

Then you stack the aligned lights.

 

You need to do this in the proper order.  Software handles this order for you.  I recommend the use of Astro Pixel Processer, which uses a series of numbered steps to get things in the correct order, which is important for many things (you also don't want to stretch the stack too soon). 

 

APP calibrates, stacks, and processes all in ONE software.  That's a serious advantage over using multiple programs that were never intended to be used together.

 

This business is more complicated than many (probably most) beginners think.
 

Edited by bobzeq25, 08 December 2023 - 08:55 PM.

[ronrrm]

Nice, I'll give the process approach a go.  I did flats/darks, no biases...next time for those.

 

I'll give APP a try.  Other posts mentioned PixInsight and Siril are candidates for a lot of the process.

 

One and done would be just fine for me.

 

Thanks for the heads up

 

Ron

[idclimber]

Nice, I'll give the process approach a go.  I did flats/darks, no biases...next time for those.

 

I'll give APP a try.  Other posts mentioned PixInsight and Siril are candidates for a lot of the process.

 

One and done would be just fine for me.

 

Thanks for the heads up

 

Ron

You can not apply flats correctly unless the bias is subtracted from the flats. They are not optional. 

[ronrrm]

I see, it was the third time out with the new gear.  I spent most of my time working out polar alignment.   I couldn't get SharpCap to do the polar alignment.  Rotating the required 90deg pointed the scope at a tree tops.  That's when I switched to NINA for a 3star alignment.   Focusing is a dream with the Zwo EAF, that didn't take long at all.

 

All that going on I glossed over the bias.  Probably take me a few more nights to get familiar with software and the processes.  Still need to run all the PDH2 guidance assistant to completion.  Eventually, I'll get into a cadence, so all the important things are done every time.

 

I haven't taken advantage of sequencing in SharpCap/NINA that might be a way for me to keep all the steps straight.

 

I think I'll stick with these two for now.  I have Stellarmate to use with a PI4, but it has so many issues I don't use it anymore.

 

Thanks for the guidance.

 

Ron

[ronrrm]

My results...

 

 

I followed a YouTube for Siril on the Deep Space Astro channel - Tutorial for Beginner.

 

Then I compared my results to AstroBackyard North American Nebula shoot...I didn't get close to his colors.  Apparently, I suck at this at this point, but I'm at least happy to have been in the right part of the sky.  I apparently missed the wall feature, but now I have something to go back to and try again.

 

So, out of this I learned not to fear FITS files, how to do the basics in Siril and Gimp, I have to dedicate more time to my imaging techniques (darks, flats, bias), and that the order things are done is ultimately important.

 

Thanks for the primer...idclimber, your advice was very helpful getting me going in the right direction.

 

Ron

 

 

[idclimber]

Your image if fine, especially for a first effort. Many struggle a lot longer and have less to show after several nights trying. It is also normal and good form to work on one thing at a time. Now that you have Polar alignment sorted, work on better focusing and then guiding. Both may take some time to optimize for best results. 

 

Both darks and bias can be taken at any time. In fact mine are about 9 months old. The only thing that matters is that they are taken at the same temperature and the same exposure/gain/iso etc. So make note of the temperatures use the same ISO, and cluster your exposures to something like 30, 60, 90, 180 seconds. Bias is done as short as your camera can go. 

 

These calibration frames can be taken in the daytime, but I would only do so in a dark room especially with a DSLR that can have light leak in tiny amounts around the eyepiece. What matters is temperature so you could do them a week or so later outside in the dark when the temperature is the same as you had on your imaging night. 

 

Once you have a set of darks that were taken at say 17 deg save the resulting integration as the Master. I label mine something like this MasterDark_iso800_17c_30sec_Dec23.fit. I dod the same for my Bias frames. Once you have a library of different temperatures you will not need to repeat them if you already have a corresponding master. 

 

As far a post processing. The current state of the art is PixInsight. It dominates with all the more experienced imagers. There are however two main obstacles, the fist being the price and probably more important the difficulty in learning it. If the cost is not a concern and learning complex software sounds like a challenge this is the way to go. 

 

APP is another option, but also costs money. It lacks the completeness of PixInsight but is far easier to get going. 

 

Siril is free and has been received updates regularly. It is fine for now and the move to PixInsight can wait until you have the image acquisition steps better mastered. 

[ronrrm]

Thanks...I'll keep at it, slowly.

 

We just joined the Milwaukee Astronomy Society, apparently the club has a version of Pixinsight and folks to tutor processing with it.  That will be a big help.

 

Ron

[idclimber]

Thanks...I'll keep at it, slowly.

 

We just joined the Milwaukee Astronomy Society, apparently the club has a version of Pixinsight and folks to tutor processing with it.  That will be a big help.

 

Ron

There is a 30 day trial that you can sign up for. 

 

The huge thing with PI now is the ability to use some very cool plugins like Russ Crowman's BlurXterminator, NoiseXterminator, and StarXterminator. These are essential tools for many here. They do however add to the cost. 

 

If you want to see what PI can do to the data that you have now. Consider uploading the integration before any processing to a shared drive and posting a link. There are numerous threads here that we do this in. I frequently process them with the the primary goal of assisting new imagers how to do so themselves. With PixInsight I or others can walk you through what we did literally step by step. In fact I can send you those steps via a file you can open in PI and follow. 

 

I also consider the Adam Block Fast Track series to be an essential element of learning the basics with PixIsnight. The cost is fairly reasonable and gets you through the awkward interface portions that few others cover well. I also consider his Fundamental series equally valuable if you have the budget for it and like his style of presentation. He has an extensive set on WBPP script used for preprocessing on YouTube for free. He has others as well on basic stretching. 

Edited by idclimber, 09 December 2023 - 12:39 PM.

[Phishin_phool]

Bias shots are easy and you can still take them. Cover your camera lens like you are shooting darks only you want to shoot as brief as you can (fractions of a sec) 30-50 are usually a good count but you could go to 100 or more. 

[ronrrm]

That's a nice offer, I'll do that once I get all my calibration masters put together.

 

I went back into Siril and played with many more settings.  Image is starting to look better.  Actually got the ridge to show up.  Still have a long way to go, but at least I'm confident I can do better with some practice.

 

Do the bias shots have to be at similar temps as darks/flats?

 

Ron

[idclimber]

That's a nice offer, I'll do that once I get all my calibration masters put together.

 

I went back into Siril and played with many more settings.  Image is starting to look better.  Actually got the ridge to show up.  Still have a long way to go, but at least I'm confident I can do better with some practice.

 

Do the bias shots have to be at similar temps as darks/flats?

 

Ron

Master Darks calibrate via subtraction Lights, as such it is ideal if we match the temperature of them to each other. 

 

Master Bias calibrate via subtraction the Flats, as such it is ideal if we match the temperature of them to each other.

 

What we are doing with either masters is simple subtraction pixel by pixel. The aim is too literally subtract the fixed pattern noise in both types of frames.

 

Of note it may be better to take the darks and bias on a cloudy night when you can better match temperatures. Often by morning it is a lot cooler and the noise profile will be less. Much depends on how much work you are willing to do on this. Many simply take darks, bias and flats at the end of the session which is likely good enough.

 

On a practical matter it is hard to temperature match if your session is all night and the swings from 20c to freezing. This is why we love cooled astro cameras. 

[ronrrm]

I see...I did record the focuser temp in the file name, that ranged from 13.21 and 12.94.  If I wait for a 55F condition, is that close enough?

 

Ron

[idclimber]

I see...I did record the focuser temp in the file name, that ranged from 13.21 and 12.94.  If I wait for a 55F condition, is that close enough?

 

Ron

I would think so. Then I would save the resulting masters so I don't have to repeat that work.

[Phishin_phool]

Effect of temp on BIAS frames is of minimal (if any) significance. If you can match it great , if not I wouldn't worry.

[ronrrm]

Here's a link to the lights, masters and Siril results.

https://drive.google...?usp=drive_link

 

I'd be interested in what can be done with these.

 

I did take another go at it once I did the other calibration frames.  Definitely made a difference.  I'm not sure what color this thing should be, but I could have made it more red but I figured I'd stop at this

 

 

 

 

[idclimber]

This is about 15 minutes of work in PixIsight. I used BXT, NXT, SXT trio. Separating the stars allowed me to work just on the nebula before bringing the stars in last. 

 

Edited by idclimber, 10 December 2023 - 11:37 PM.

[idclimber]

I did not notice until after I uploaded, but apparently PI read the file slightly off and it is flipped vertically. I wondered why it would not plate solve so I could do a SPCC.

[idclimber]

Here it is with a 100% crop over the Cygnus wall section of the image. And I corrected the orientation. this will also you to see what the detail looks like.

 

 

 

 

 

[ronrrm]

Nice...colors pop a bit more, and the Wall shows up amazingly clear. 

 

Siril did the same thing; it flipped the image the second time I went through the process; not sure why.

 

Once it was flipped and even when I flipped it back, Siril couldn't plate solve for color calibration (it worked for my first attempt...dunno why it failed the next time).  I just tried to set the colors manually and went for the brown/organish look since it brought out a lot more detail.  Not sure what this thing actually should look like, but I like your rendition.

 

I'm going to practice again with Siril and see if I can get to the similar image as yours.  Siril was easy enough to work with, especially since it integrated Starnet to remove the stars early in the process and then add them back after curves/levels adjustments.  In my last image, I didn't push the stretch on the stars, to keep them more or less the same size as in the original.

 

Then I'll move on to PI.

 

I'll watch some you-tubes for the process work-flow.

 

I think my plan will be to re-process until I get similar results, while it's cloudy/cold, then re-shoot/process the entire data set on the first available night.  This was kinda a cobbled up data set.

 

If there is any other advice or criticisms, I'm open to it.

 

I think I'm fairly comfortable with polar alignment, guiding and focusing.

My mount guides somewhere around 1-2 arc sec, dunno how good or bad that is, but it is repeatable.

I need to learn more about choosing the right exposure and gain.  SharpCap and Nina both have stuff to help with that (more Nina than SharpCap).

I mostly shoot from my bortle 5 back yard, so I'm learning more about 'lucky imaging' and how that can improve image quality.

 

 

I shot this with both 20sec/Gain-100 x200 or so and 40sec/Gain-350 x200 or so.  

 

The camera has a 585 sensor, the read noise drops off at 250.  I think I'll use 250 gain and 30sec exposures as my next experiment.

 

Ron