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Good Mineral Moon Results Despite Low Elevation

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#1 aeroman4907

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Posted 03 March 2021 - 04:03 PM

I did some testing on the Moon this morning.  The primary test was to image with low gain and a bit longer exposure (16ms with a gain of 4 in Firecapture).  The secondary test was to attempt to tune an ADC simply off of the Moon.  Tuning the ADC was a real challenge for me.  It took about 10 minutes to arrive at what I thought was a reasonable tuning, but I had no idea if it in fact was any good.  It turned out to be quite good.  Here is a stack of 250 frames out of 2,000.  With the align RGB channels with AS!3, in addition to my tuning, I found no issues with diffraction whatsoever, even with a highly saturated "Mineral Moon.".  As the Moon was only 38° in elevation, the seeing was only fair with a Pickering of about 3 in an 8" scope.  I was extremely pleased with the results.  Here is a cropped region around Hommel.  It is presented at the native capture scale of close to 0.23"/px.  This gives me more confidence to image the Moon at earlier crescent phases as well as during the summer. Be sure to click on the image for full size!

 

Hommel.jpg


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#2 Kenny V.

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Posted 03 March 2021 - 04:14 PM

That is a very nice result, both in its coloration and sharpness/detail.

 

Ken


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#3 jeffry7

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Posted 03 March 2021 - 04:23 PM

What does tuning the ADC mean? What is involved?
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#4 CoHPhasor

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Posted 03 March 2021 - 05:21 PM

There are several prisms or planes, inside the ADC.
It isn't a 'magic' corrector, but instead the user must fine tune the alignment by hand.
(two screws are attached to the planes and you must move them)


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#5 Tom Glenn

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Posted 04 March 2021 - 02:32 AM

Nice image Steve, of this very crater-rich region! 


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#6 aeroman4907

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Posted 04 March 2021 - 07:29 AM

What does tuning the ADC mean? What is involved?

 

There are several prisms or planes, inside the ADC.
It isn't a 'magic' corrector, but instead the user must fine tune the alignment by hand.
(two screws are attached to the planes and you must move them)

Thanks for chiming in CoHPhasor.

 

I don't know if there is a particular misalignment in my ZWO ADC, but I find that if I try and place the alignment screw horizontally, my adjustments of the levers never are properly adjusted an equal distance opposing the central "screw".  I generally have the levers offset but are on one side of the horizon line.  It makes the process feel much less scientific to me and is partially why I leave the ADC in the box as much as possible when I image.  The relatively few times I have used it I have managed to get good results, but it is only with a fair amount of work and trial and error.



#7 Borodog

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Posted 04 March 2021 - 09:52 AM

That’s an excellent result, aeroman. Ever so slight hint of fringing around the lower illuminated rims of some craters, but I would not have noticed had I not been looking for it because of your text.
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#8 CoHPhasor

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Posted 04 March 2021 - 01:18 PM

Thanks for chiming in CoHPhasor.

 

I don't know if there is a particular misalignment in my ZWO ADC, but I find that if I try and place the alignment screw horizontally, my adjustments of the levers never are properly adjusted an equal distance opposing the central "screw".  I generally have the levers offset but are on one side of the horizon line.  It makes the process feel much less scientific to me and is partially why I leave the ADC in the box as much as possible when I image.  The relatively few times I have used it I have managed to get good results, but it is only with a fair amount of work and trial and error.

  The orientation of the ADC is key, and the new units have a bubble level on them to help clear that up.
(Balanced to the horizon line)


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#9 aeroman4907

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Posted 04 March 2021 - 01:23 PM

  The orientation of the ADC is key, and the new units have a bubble level on them to help clear that up.
(Balanced to the horizon line)

I wonder if they sell the bubble level for a slightly older (3-1/2 years) ZWO ADC.  I have a small one that I press against the screw which is not the most accurate means of determining level.

 

P.S.  I guess they do.  Looks like another purchase...

 

https://agenaastro.c...el-for-adc.html


Edited by aeroman4907, 04 March 2021 - 01:25 PM.


#10 CoHPhasor

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Posted 04 March 2021 - 06:42 PM

I didn't realize there was an option to get the bubble ring.... looks like another purchase for me too!  lol.gif 


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#11 jeffry7

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Posted 04 March 2021 - 08:46 PM

There are several prisms or planes, inside the ADC.
It isn't a 'magic' corrector, but instead the user must fine tune the alignment by hand.
(two screws are attached to the planes and you must move them)


When I saw the acronym ADC, I thought it was Analog to Digital Converter. I couldn't imagine what user accesible tuning there would be for this.

A search on ZWO ADC was enlightening.
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#12 John_Moore

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Posted 04 March 2021 - 09:57 PM

Adjustment of optics can always be tricky.

 

However, info here (pdf paper) on the whole ZWO ADC setup (do also click the enclosed links -- very useful).

 

Do check out this too -- concerning an ASH ADC,  as well as this more technical description

 

John Moore


Edited by John_Moore, 04 March 2021 - 10:15 PM.

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#13 aeroman4907

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Posted 05 March 2021 - 09:55 AM

Thanks for the reference documents and a refresher John.


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#14 aeroman4907

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Posted 05 March 2021 - 09:58 AM

When I saw the acronym ADC, I thought it was Analog to Digital Converter. I couldn't imagine what user accesible tuning there would be for this.

A search on ZWO ADC was enlightening.

In a way it is a part of an "analog" to digital converter assembly.  The analog of "light" is modified by the ADC and is ultimately converter to "digital" by the imaging camera.



#15 Jaimo!

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Posted 07 March 2021 - 06:24 PM

FireCapture has an ADC alignment feature, it makes the process much (a little) easier.

 

Do you feel you actually need the ADC, I understand using it for the planets as they as so low in the northern hemisphere; but the moon should rise high enough, over 30 degrees, to not need the ADC?


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#16 Tom Glenn

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Posted 07 March 2021 - 07:07 PM

Do you feel you actually need the ADC, I understand using it for the planets as they as so low in the northern hemisphere; but the moon should rise high enough, over 30 degrees, to not need the ADC?

Mars required an ADC above 60 degrees this year.  Only at values above 70 degrees or so would the adjustments become negligible.  But this assumes color imaging of course.  If filters are used for monochrome imaging of the Moon (with suitable camera, of course), then there will be far less impact of dispersion.  


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#17 aeroman4907

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Posted 08 March 2021 - 08:34 AM

FireCapture has an ADC alignment feature, it makes the process much (a little) easier.

 

Do you feel you actually need the ADC, I understand using it for the planets as they as so low in the northern hemisphere; but the moon should rise high enough, over 30 degrees, to not need the ADC?

FireCapture does indeed have an RGB align feature that I utilize at all times as I do have a OSC sensor, but I find even with this feature color fringing begins to be an issue when the Moon is about 45° in elevation and below.  I'll being doing a more enhanced evaluation of my images as they related to elevation and dispersion utilizing only RGB align in the future to try and pin down when I should use it or not.  The back focus isn't precisely right with my current setup using the ADC, so I get concerned that it might impact the quality of images on my relatively wide field IMX183C sensor.  That being said, I haven't observed any apparent degradation of the images at the corners of the sensor, but since the seeing wasn't great due to the low elevation to begin with, I haven't had hyper sharp images with the ADC to make that determination.


Edited by aeroman4907, 08 March 2021 - 08:36 AM.



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