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My first try at Lunar imaging

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#1 Strykyr22

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Posted 21 April 2021 - 11:53 AM

I got into astronomy about 4 months ago and then quickly started doing EAA about 2.5 months ago. Here is my first try at lunar imaging Apr 20/21:

 

C6 Evo, ASI385MC, f/6.3 reducer

Sharpcap Pro, 2.4ms exposures, gain 150, 2000 frames

Processed in autostakkert, best 10% frames, 1.5x drizzle

 

Any tips are appreciated.

 

Lunar North Apr 20, 2021
 
Lunar Equator Apr 20, 2021
 
Lunar South Apr 20, 2021

 


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#2 Nick Dangerr

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Posted 21 April 2021 - 12:03 PM

Those look very nice! (of course, I'm just a visual observing guy :)


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#3 dcaponeii

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Posted 21 April 2021 - 01:38 PM

I'm thinking Mosaic there.  Almost got the whole disk.



#4 Borodog

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Posted 21 April 2021 - 02:35 PM

Nice. Some things to experiment with:

 

1) Try shooting at whatever gain minimizes noise for your camera if you haven’t already. 2.4 ms is plenty short and you have some room to go up without blurring.

2) experiment with stacking more frames, especially if you are reducing the final image for presentation. Always check the absolute quality numbers for the best and worst frames, not just the quality graph, which is extremely deceptive.

3) skip the drizzle.

4) have you sharpened/deconvolved? It makes a huge difference.



#5 Borodog

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Posted 21 April 2021 - 02:36 PM

Also, yes, stitch a mosaic!



#6 Strykyr22

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Posted 21 April 2021 - 09:52 PM

I'm thinking Mosaic there.  Almost got the whole disk.

What is the easiest program to make the mosaic? I have the pictures saved as png

 

Nice. Some things to experiment with:

 

1) Try shooting at whatever gain minimizes noise for your camera if you haven’t already. 2.4 ms is plenty short and you have some room to go up without blurring.

2) experiment with stacking more frames, especially if you are reducing the final image for presentation. Always check the absolute quality numbers for the best and worst frames, not just the quality graph, which is extremely deceptive.

3) skip the drizzle.

4) have you sharpened/deconvolved? It makes a huge difference.

Thanks for the tips.

1. Looking at the ASI385 the mode switch and read noise drop happens a 60 gain. I guess I just had gain at 150 because unity gain is at 135. I'll try 60 next time.

2. Do you have a general guide for this? I went back to the data, frame 1 is 1073048, 200 is 924409, 1000 is 847858, and 2000 is 709180. Is there a percentage of the first number that is a good cutoff guide? See below for my test. I actually like the 5% stack or 10% stack best.

3. Will do. I tested this and 100% agree. Is drizzle for planets only? Or when should I use it?

4. I have ticked the box "Sharpened - blend with RAW" and I left it at 50%

 

1% of 2000 frames

1 percent No drizzle
5%
5 percent No drizzle
10%
10 percent No drizzle
30%
30 percent No drizzle
50%
50 percent No drizzle


#7 dcaponeii

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Posted 22 April 2021 - 09:29 AM

I usually just stitch my lunar images together manually in PaintShop Pro 2021 by pasting the images as layer on a blank canvas with a black background.  As you add each layer you can increase the transparency of the top layer with the opacity slider and once aligned return the opacity to 100%.  Tweak the contrast and brightness to match across the boundary with the layer underneath and then merge them together.  You can always use an eraser tool with feathering at maximum to erase the border between layers before merging if you can find a good contrast and brightness to blend them perfectly.  Curves is also useful for adjusting the top layer at the boundary.  Usually doesn't take more than 15 or 20 minutes total with 8-10 images to merge.



#8 Borodog

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Posted 22 April 2021 - 04:44 PM

I use Microsoft ICE for stitching mosaics. It seems like Microsoft no longer distributes it, so you may need to use something else.

 

As far as what to do with the absolute quality numbers, that is up to you. But I think it's a necessity to understand the real range. If the entire range of quality only falls by 5% from best frame to worst frame, then you are throwing away great data if you don't use most of it. If on the other hand the absolute quality falls by a third as in your case, it makes much more sense to stack fewer frames.

 

Your 5% and 10% stacks certainly are sharper than the 50% here, without much noticeable penalty in terms of added noise, although that may have been cleaned up some by resizing them to fit the 1600 pixel rule here; I'm not sure.

 

The sharpening done by Autostakkert is a simple unsharp mask. I think your latest image here is looking very sharp and is presented at a good resolution. The main problem is that you've blown out the highlights during capture; there's no way to recover from that. Other than that, I think you've got a very nice image of the south polar region.


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