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Seeking advise, my proposed M57 project

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#51 josh smith

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Posted 04 June 2016 - 11:48 AM

Spent most past weeks fighting amp glows, which made me yearning for somethings better, like the 1600, and a C11, combined to make shorter integration time.

 

At least I have finally determined the sweet spot where most of the glows can be removed.

 

This is  about 25 hours of Ha integration from the "test runs" so far.  The next 25 hours should be more efficient use of time, that is my hope.

 

Looking good and I believe the next tier halo is starting to show up!  I wonder if you might have some raw data to look at once you get a good stack.  Just this view makes me question your focus.  The stars just don't seem to have any sharp definition at all.  I know that can happen to some extent with very deep narrowband exposures, but I wouldn't expect them to be this soft.



#52 FirstC8

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Posted 04 June 2016 - 02:16 PM

Thanks Josh. I can share all the raw subs with you.

Focus believe it or not wasn't my priority. In order to not be sleep deprived, I decided to only focus once on Alkaid earlier at night, then do the adjustments, and when M57 is high enough frame it and start the sequence, let it rip through the night and only come back after sunrise to close out the session.

As such there are sharp subs and blurry subs during any one session, a lot has to do with seeing because my CEM60 only provides pinpoint tracking when seeing is great, and that usually happens when the scope slews near Meridian, which also happens to be where Alkaid was at when I did the focusing earlier that session.

For now though I have no luxury to pick only the best focused subs, but as I accumulate more of them, eventually will be able to pick and choose.

The halos BTW don't change sharpness much regardless of focus or seeing. This is why I decided not to bother.

Ideally a fully automated setup would help a lot, but I decided this time around to keep my basic setup as is.

The core will be replaced with best focused images use layer masking in final processing. At least this is the plan anyway.

Appreciate any comments on my plan, and suggestions. I may not be able to implement all suggestions due to the limitation above, but will try my best.

#53 FirstC8

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Posted 15 June 2016 - 01:32 PM

I am at over 50 hours of Ha time, and think it is at the point of diminishing return. The slow scope, seeing, guiding and camera limitations seem to conspire to not allow the second tier halo to show well.

The image also suffers from minimum Oiii and Sii times. Not only that the Oiii channel was from one of the earlier sessions that had severe amp glow and banding issues. The issues have been finally minimized by trial and error to find the exact exposure time/gain/temp setting.

That's right, there is only a very narrow exposure setting when the amp glow and banding can be almost calibrated out.

Basically my camera is limping along and knock on wood it will last till the end of this project.

Once more Oiii and Sii times are added, hopefully color balance can be reached, then the core will be layered with higher res shorter exposure subs for HDR treatment.

Attached Thumbnails

  • M57HaSHO1st.jpg

Edited by FirstC8, 15 June 2016 - 01:34 PM.


#54 syscore

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Posted 15 June 2016 - 02:03 PM

The only thing I can think of that would stop you from getting the second ring is light pollution because that would introduce a noise term in every sub that is larger than the signal from the second ring. Do you know what your sky brightness is?

 

And I am taking into account that your subs are long and read noise is low.


Edited by syscore, 15 June 2016 - 02:04 PM.


#55 FirstC8

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Posted 15 June 2016 - 02:45 PM

Don't know, what do you use to measure LP? My subs are very long, right around 3260s, necessary to overcome amp glow and bandings. But I think read noises are too high, in part because I am forced to do such long exposures.

After this exercise will upgrade my camera. If I am using a camera similar to the ASI1600, could have saved a lot of time.

There is always next year.

Edited by FirstC8, 15 June 2016 - 02:47 PM.


#56 syscore

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Posted 15 June 2016 - 02:55 PM

Read noise is constant, per sub, not per time. If you read noise is 8 e- for your camera, it is 8 e- regardless of whether you do a 0.1s sub or a 3600s sub. That is why stacking a lot of shorter subs is more noisy than fewer subs. In your case, your subs are very long and read noise would be low.

 

I use an SQM meter to measure my sky brightness. Do your skies seem bright?


Edited by syscore, 15 June 2016 - 02:56 PM.


#57 FirstC8

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Posted 15 June 2016 - 07:34 PM

Hey syscore, if possible, I wish you could take some more 900s M57 Ha subs for stacking. I think you and I have similar LP level.

You have demonstrated both the 8300 and 1600 will benefit from long exposures going after the faints in that 8300 thread.

I will post my own latest Ha stack. It will be a great way to show how much improvement the better chips such as 8300 and 1600 can do for faints at our typical home sites, therefore benefit a lot users.

I am seriously due for hardware upgrade, better tracking, better focusing, and a chip that can provide consistent calibrations, but doing so now will disrupt the routine so after this M57 season is over.

Edited by FirstC8, 15 June 2016 - 10:41 PM.


#58 FirstC8

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Posted 15 June 2016 - 10:46 PM

On a side note, your 8300 chip visuals on the impact of read noise to short and long exposures were very intuitive, I hope you start your own thread on the subject so we can use them as reference.

#59 syscore

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Posted 15 June 2016 - 11:02 PM

I'll just post them here ...

 

11" EdgeHD @1960 mm, QSI-683 (8300), 75 x 60 seconds, 1x1, (75 Minutes total) ...

 

M57_75x60s_Crop.png

 

11" EdgeHD @1960 mm, QSI-683 (8300), 5 x 900 seconds, 1x1, (75 Minutes total) ...

 

M57_5x900s_Crop.png

 

The reason that the dimmer detail is visible in the second stack, and not the first, is that it hidden by the read noise in the first stack. Read noise occurs when the frame is read from the sensor and is constant regardless of the length of the exposure. Thus, the more exposures you do, the more you pile on the read noise. To control for this, you do fewer but longer exposures.


Edited by syscore, 16 June 2016 - 02:31 PM.


#60 FirstC8

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Posted 16 June 2016 - 01:28 PM

Thanks syscore.

Now that read noise is overcome, and the sweet spot is determined to minimize amp glow and banding, I need to pay more attention to focusing, and just hope seeing can improve as summer takes hold.

The good news is M57 is moving to earlier at night so manual focusing can be done without losing too much sleep. The bad news is M57 will also soon move away from the best part of the sky.

In the end, our typical LP sites will likely still be the curse. I have not seen enough examples to convince me otherwise.

Admittedly with my current basic setup I am not the best candidate trying to prove otherwise.😆

Edited by FirstC8, 16 June 2016 - 01:33 PM.


#61 syscore

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Posted 16 June 2016 - 02:32 PM

I fixed the scope spec, for some reason I wrote 80 mm APO, I guess because that was what I was using last night. Those images were done on my 11" with a reducer.



#62 Hobby Astronomer

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Posted 16 June 2016 - 09:14 PM

gallery_225131_300_27449.jpg

 

Might try a high QE NABG camera with large pixels. This one has a full well depth of 100,000. I believe the 8300 has a full well depth of around 25,000.

 

HA


Edited by Hobby Astronomer, 16 June 2016 - 09:17 PM.


#63 Hobby Astronomer

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Posted 16 June 2016 - 09:23 PM

C8,

 

Next time out will try for M57 and post up the results. See how long it takes to get the other rings. The image above was only stretched with no other processing. 

 

HA



#64 syscore

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Posted 16 June 2016 - 11:24 PM

Well depth wouldn't matter, but QE would. What is the QE on the 1603?



#65 FirstC8

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Posted 16 June 2016 - 11:52 PM

C8,

Next time out will try for M57 and post up the results. See how long it takes to get the other rings. The image above was only stretched with no other processing.

HA

That would be awesome HA!

I assume your site also has typical LP.

I found some time to restack only the best 25 hours out of the 50 hours Ha subs, and the halos got dimmer (of course) but resolution improved.

If any of you can demonstrate your chip is capable of revealing the halos in much less exposure time with similar light train, that will prove my chip is part of the problem, which would not surprise me, it is after all a planetary imaging chip by design.

Edited by FirstC8, 16 June 2016 - 11:54 PM.


#66 FirstC8

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Posted 19 June 2016 - 12:31 PM

As explained in the past, I have been battling with banding issues with my chip. So far have found exposure sweet spots for the Ha and Sii channels. But similar sweet spot applied to the Oiii channel would completely blow the Oiii core.

I have no time to continue to fiddle with exposure time, gain, setpoint... so the question is can I do bicolor with just Ha and Sii?

I have seen Ha and Oiii bicolor for M57, but not sure Ha and Sii would work since Sii does not show halos. But it is what it is. QHY has been not much help.

If Ha and Sii bicolor can work, please provide some links on how to do bicolor. I will then collect only Ha and Sii hours for as long as M57 allows me to collect. Thanks!

#67 EFT

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Posted 20 June 2016 - 04:55 PM

gallery_225131_300_27449.jpg

 

Might try a high QE NABG camera with large pixels. This one has a full well depth of 100,000. I believe the 8300 has a full well depth of around 25,000.

 

HA

 

By George I think you're getting it.  Good job!



#68 FirstC8

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Posted 20 June 2016 - 05:31 PM

A $5K camera could certainly help, the ASI1600/FW/NB at $2K would likely help too.

In fact if my camera had not having the banding issues forcing me to throw out more than half of the subs, I would have been in a much better shape.

As it stands, at least I have finally narrowed the issue down to bad darks, darks with clear tiled gradient and vertical lines that are not present in lights and biases.

I have sent QHY the files and they have yet got back to me. Wil have to continue to collect data in the "limbo" mode.

#69 FirstC8

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Posted 22 June 2016 - 01:05 PM

The latest SHO version. More Oiii and Sii time balanced star color a lot. Still need a lot of Ha time to further tighten the stars, reduce sky noise, and hopefully also bring out the halos more, especially the second tier.

Finally also need to layer the core over.

Attached Thumbnails

  • efBDmh_vIsaUhpq9R6L_vOu28ccVULIriDluNl7_qsQLAYspN.jpeg

Edited by FirstC8, 22 June 2016 - 01:07 PM.


#70 FirstC8

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Posted 26 June 2016 - 10:05 PM

Having a hard time bringing out more second tier halo.

Blending the core with the halos also proved difficult due to high contrast. Had to saturate the core before I could reasonably match the color of the nearby halos.

Will continue to collect Ha and Oiii data but not holding my breath much more can be done.

Attached Thumbnails

  • X3L4IYdgtZC8ChcAaI0m7EFCSzjy_MsmMKyUPjU-zB8LAYspN.jpeg

Edited by FirstC8, 26 June 2016 - 10:06 PM.


#71 syscore

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Posted 26 June 2016 - 10:14 PM

That is looking pretty good. Nice dedication!



#72 FirstC8

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Posted 27 June 2016 - 12:10 AM

That is looking pretty good. Nice dedication!


Thanks, many factors limited the details I could get. It was a fun exercise, made possible by having a semi permanent location not having to move things around.

#73 FirstC8

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Posted 10 July 2016 - 08:43 PM

As time starts to run out, additional exposures continue to add on whenever possible.

There is no chance to further reveal fainter halos, no improvement in more details either, limited by the equipment, but background noises can still come down further, making for a cleaner image. Even the overblown stars can now be brought down a little.

Attached Thumbnails

  • O18Ra0o7Qv561qga7rA3yHp2MD0xKZcZtV5j7aMkWugLAYspN.jpeg

Edited by FirstC8, 10 July 2016 - 08:44 PM.


#74 scottk

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Posted 16 July 2016 - 03:57 AM

Is this all through that qhy mini cam thing? 

 

Haven't been here in a long while to check on things. If so, that's looking awesome!!!



#75 FirstC8

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Posted 16 July 2016 - 09:57 AM

Yes from the mini. Color balance is still very hard to do because I don't have nearly as much time for Oiii and Sii.

Maybe LHaRGB combination would look cleaner, but for some reason I am drawn to the Hubble SHO palatte.

It looks unnatural to our eyes, yet the universe is anything but what we thought it should be.😊


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