New to AP seek advice

[MarcoS]

Good day,
I'm coming from underwater photography and I just got bitten by the AP bug.
While looking for a software to do the post processing I came across StarTools, and need some advice....
I took this pic with this set up:
Meade LS6" Light Switch Telescope, bader UHC-S filter, Camera Olympus XZ1 connected afocally to EP Hyperyon 36mm.
there were 39 x 15sec frames at f2,5 stacked with DSS here is the output file:

https://drive.google.com/file/d/0B6oGP3 ... sp=sharing

Following tutorials on this site, and advises from an other topic in this forum I managed to make this:

https://drive.google.com/file/d/0B6oGP3 ... sp=sharing

Well, if I see around other pics of M42 mine does not look very nice

can you please advise what i could be doing wrong, and waht is the best way to get results from those data?

thanks and best regards
Marco

[admin]

Hi Marco,

Welcome to the wonderful world of AP!

Your are not doing anything wrong perse - data acquistion is tough!
Actually you have done quite well considering you are imaging afocally, with a smaller 1/1.6" sensor, and at a significant magnification.
Were the subframes RAW files? If so, did you convert the RAW files in DSS, or with some other utility?

Imaging afocally will introduce extra glass in the optical train. It appears some of the glass exhibits some chromatic aberration (you can see the stars have been shifted blue and red).
Nevertheless you have resolved the individual stars in the trapezium perfectly. You got the reddish Hydrogen alpha shockwave as well.

What I would do at this stage is try to widen the field and take longer exposures. Prime focus photography would be ideal, but I don't believe your camera has a detachable lens, does it? Prime focus will allow you to take flat frames and dark and/or bias frames as well. However, if you must image afocally, perhaps try a focal reducer (which does add more glass unfortunately) for a wider field.

This is what I came up with in 1.3.5.279RC;

MarcoS_Trapezium.jpg (80.47 KiB) Viewed 12807 times

This is what I did, roughly;
Opened file, indicated it was still linear.
--- Auto Develop
To see what we're working with. Default settings.
--- Crop
Removed stacking artifacts.
Parameter [X1] set to [96 pixels]
Parameter [Y1] set to [163 pixels]
Parameter [X2] set to [1647 pixels (-386)]
Parameter [Y2] set to [1445 pixels (-57)]
--- Wipe
Vignetting preset.
Parameter [Dark Anomaly Filter] set to [5 pixels]
--- Auto Develop
Final global stretch (redo stretch).
Created a ROI (click & drag) over the trapezium area.
Parameter [Ignore Fine Detail <] set to [3.0 pixels]
--- Wavelet Sharpen
I wanted to do some Decon before this as well, but the data is too noisy for the algorithm to latch onto any hidden detail.
Parameter [Intelligent Enhance] set to [Yes]
Parameter [Scale 1] set to [20 %]
Parameter [Amount] set to [475 %]
Parameter [Small Detail Bias] set to [98 %]
--- HDR
Reveal preset.
--- HDR
Optimize preset.
Parameter [Detail Size Range] set to [129 pixels]
--- Color
Not totally happy with the colors, although the core is meant to be greenish (rich in OIII emissions, while the Ha 'shockwave' should be visible in red).
Parameter [Cap Green] set to [No]
Parameter [Dark Saturation] set to [1.50]
Parameter [Bright Saturation] set to [2.30]
Parameter [Saturation Amount] set to [348 %]
Parameter [Blue Bias Reduce] set to [1.33]
Parameter [Green Bias Reduce] set to [1.29]
--- Wavelet De-Noise
Switched Tracking off.
Parameter [Scale 1] set to [90 %]
Parameter [Scale 2] set to [97 %]
Parameter [Scale 3] set to [97 %]
Parameter [Color Detail Loss] set to [24 %]
Parameter [Brightness Detail Loss] set to [25 %]
Parameter [Read Noise Compensation] set to [13.63 %]
--- Crop
Parameter [X1] set to [319 pixels]
Parameter [Y1] set to [257 pixels]
Parameter [X2] set to [1115 pixels (-436)]
Parameter [Y2] set to [1093 pixels (-189)]

Now there are more/different things we could do to make the most of this specific case of data, but I'd like to give you a workflow that is close to a generic workflow that works with most data.

Hope this helps!

[MarcoS]

Hi Ivo,
Thanks for the advice!
Yes I'm realizing that data acquisition is not easy, and here the weather conditions do not help neither....
The frames were RAW stacked and converted in DSS, and I had dark, flats, and bias to go with them.

Could it be that the chromatic aberration was caused by the bader UHC-S filter that I was using? If I take the filter in my hand and look trough it I see a much darker back ground, but around the street lights that are much dimmed I can see a separate red and blue halos.
The LS6" scope is a ACF model, so it should not have aberration, and with the camera I have took lots of underwater photos with all kind of added wet lenses and never experienced chromatic aberrations, The Hyperion 36mm where my camera is attached should also be aberration free.
I will check the optical train to see if I found how is causing (if this is possible to check)
Is there a way to get rid of this aberration with software?

It is correct, I cannot take the lenses of the camera away, so for the moment I have to live with afocality...
I have the Antares f6,3 focal reducer, but due to cloudy sky I have not been able to try it out yet.
I will try it out with longer exposures and more frames as the clouds open up.

Thanks for showing the workflow, I will keep playing with all the settings in it to understand better what they do.
one of biggest problem that I have is that I do not have a reference image/view that show the real colors of a DSO, if we can say "real" to them....
Nice software bay the way !
If I understand correctly it is possible with it to achieve a final perfect image (starting from good data) without the use of any additional software?
For the per-processing/stacking is DSS the better choice, or do you advise something else?

best regards
Marco

[admin]

Hi Ivo,
Thanks for the advice!
Yes I'm realizing that data acquisition is not easy, and here the weather conditions do not help neither....
The frames were RAW stacked and converted in DSS, and I had dark, flats, and bias to go with them.

Could it be that the chromatic aberration was caused by the bader UHC-S filter that I was using? If I take the filter in my hand and look trough it I see a much darker back ground, but around the street lights that are much dimmed I can see a separate red and blue halos.

The perceived chromatic aberration could also be caused by DSS not aligning the channels properly. My hunch is actually that DSS has trouble aligning the channels because of chromatic aberration. If I align the channels better with the Lens module before processing (it's a bit of a hack - tell ST the data is modified/not linear when you load it, launch the Lens module, change the Y values for blue and red until no color fringing can be seen in the trapezium stars, then when you're done, switch Tracking on manually - we want Tracking to be aware of the re-alignment as it will try to take it into account during all other subsequent steps!).
Once re-aligned, subsequent processing still reveals single color fringing around the stars - it's a bit hard to tell if that is really chromatic aberration though.

The use of the UHC-S filter does explain why I had trouble with the color calibration - it is impossible to recover true color balance once the data has been filtered like this (something to be aware of - it's not the end of the world though!).

The LS6" scope is a ACF model, so it should not have aberration, and with the camera I have took lots of underwater photos with all kind of added wet lenses and never experienced chromatic aberrations, The Hyperion 36mm where my camera is attached should also be aberration free.
I will check the optical train to see if I found how is causing (if this is possible to check)
Is there a way to get rid of this aberration with software?

Yes, StarTools offers the Filter module which, among other things, can get rid of the chromatic aberration telltale blue/purple fringes.

It is correct, I cannot take the lenses of the camera away, so for the moment I have to live with afocality...
I have the Antares f6,3 focal reducer, but due to cloudy sky I have not been able to try it out yet.
I will try it out with longer exposures and more frames as the clouds open up.

Thanks for showing the workflow, I will keep playing with all the settings in it to understand better what they do.
one of biggest problem that I have is that I do not have a reference image/view that show the real colors of a DSO, if we can say "real" to them....

Good point. "Real" color of DSOs is much debated. That said, we can go by the emissions spectrum of DSOs, as well as the black body emissions of stars in the visual spectrum.
So, as a rule of thumb;

Ha = deep red
Hb = cyan
N2 = deep red
S2 = deep red
OIII = green
HII regions (ex. found in most galaxies) are usually a mixture of Ha and Hb such that the color looks purple
Galaxy cores = yellow
Galaxy outer rims = blue
Stars in your image should range from deep red, to orange, yellow, white, to blue.

Nice software bay the way !
If I understand correctly it is possible with it to achieve a final perfect image (starting from good data) without the use of any additional software?

Thank you! And yes, that is correct - StarTools should take you all the way from raw data to post-processed result.

For the per-processing/stacking is DSS the better choice, or do you advise something else?

I've had some trouble with DSS myself and unfortunately wouldn't rate it the absolute best out there. However it is adequate for most situations once you've found the right settings and have worked around its idiosyncracies. Better (but more costly) stacking solutions come from CCDStack and PixInsight (the latter also does post-processing, but is notoriously difficult to operate and is considered a previous-generation competitor to StarTools. They have a 45-day free trial though, so give it a try!).

[MarcoS]

Hi Ivo,
Thanks for the advices!
I have reworked the image following the workflow you gave, and I started the process by realigning the red and blu channels.
I thing I got rid of the aberation.
Please see the results here:
https://drive.google.com/file/d/0B6oGP3 ... sp=sharing

I have given a try to CCDStack and it remained on my pc for about 2minutes.. It did not want to load my Olympus RAW files...
PixInsight I have requested a trial licence, but looking at the info to be found on the web the first impression is not very good, the interface is a bit cluttered I think..

And then I got yesterday night clear skyes and I tried M42 again with th Antares focal reducer and no filters.
11 minutes total exposure in 20 seconds subframes Meade LS6" Olympus ZX1 afocaly on 2" EP Hyperion 36mm

This is what I managed with the data:

orion-no-filter3.JPG (42.18 KiB) Viewed 12779 times

The workflow was similar to the one advised. By the way is there a log feature in program so that I see what for steps has been done?

Here is the Fts File:
https://drive.google.com/file/d/0B6oGP3 ... sp=sharing

Getting better I think, but there are tons of tweaking that I have to learn in your program...

Best regards
Marco

[admin]

That looks much better indeed!

I have given a try to CCDStack and it remained on my pc for about 2minutes.. It did not want to load my Olympus RAW files...

If you don't mind using the command line, you could use dcraw to convert your RAW frames first, so that CCDStack can then use them.

PixInsight I have requested a trial licence, but looking at the info to be found on the web the first impression is not very good, the interface is a bit cluttered I think..

Yep. It's one of the major reasons why I wrote StarTools...

This is what I managed with the data:

orion-no-filter3.JPG

That looks very, very nice!

By the way is there a log feature in program so that I see what for steps has been done?

Yes, there is. It's a file called 'StarTools.log' and should be located in the same folder as the executable etc.

Getting better I think

Most definitely - you're a quick learner!

[MarcoS]

Hi Ivo,
Next question that I have, is how to get rid of them red and bluish pixels around the image.
see for example this picture of the double cluster:

double cluster2.JPG (71.15 KiB) Viewed 12762 times

I have tried lots of options but I am not winning...
can you please advise?

FTS file if you need it is here:
https://drive.google.com/file/d/0B6oGP3 ... sp=sharing

thanks and best regards
Marco

[admin]

This latest data shows some extreme vignetting;

doublecluster1.jpg (168.57 KiB) Viewed 12754 times

I'd love to know how those pixels came into being as they seem aberrant to me. Quite honestly, I've never come across anything like this!
Their background is clipping (pur black) which is almost never the case with stacked images (the data is never pitch black - there is always some signal). Something very strange/bad is going on...
It's almost like flat frames and or bias were applied incorrectly.
Did you use any flats/bias frames?

[MarcoS]

Hi Ivo,

Yes I did use flat and bias, here the jpeg version of the files:
Flat

flat.JPG (46.28 KiB) Viewed 12749 times

Bias

bias.JPG (33.33 KiB) Viewed 12749 times

now that you bring my attention to the flats,it looks like not all the cip of the camera is lighted, could it this be the problem?
pics where taken afocaly with the camera attached to a bader Hyperion 36mm 72°

On the other side all the previous pics that I posted were also taken with this setup...

best regards
Marco

[admin]

Hmmm... The purpose of flats is to compensate for uneven lighting. Definitely seems like the flats are not applied appropriately (they seem to make the problem worse, not better!). Hard to say why...