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First attempt at close ups - any suggestions?


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I've decided to have a go at lunar imaging but trying to get the most out of my kit before I work out what else might help. I've previously focused on full disc images so this is my first attempt at getting closer.

The images don't quite meet expectations, although expectations tend to be based on the best of what I see on the internet, and so are probably entirely unrealistic for a 1st effort. 

Main reason for posting is that I don't know what I need to work on - so just wanted to post my workflow and see if anything jumped out?

These images were taken with a 250PDS Newt + 2.25x barlow + ASI120MC-S. I also have a mono CMOS camera with the same pixel size/larger chip. I chose to go with this combination as it seemed like the simplest way to get started  - largest aperture of the newts I have +a  color camera. The camera chip size is also relatively close to the diffraction limited field for the scope/barlow, although I haven't got as far as working out how much I ought to worry about this.

Working everything out for this setup I get:

image.thumb.png.3396c1c19bc5ef66d54f4e2281975d02.png

I posted previously and got some good info on f-ratio vs pixel size, diffraction limited fov, etc. I realize this isn't exactly correct, but I don't believe it's a million miles away (and it's also what I have!).

 

Process was:

- focus on the moon using the surface focusing methods in Sharpcap - this clearly worked, but seeing made it impossible to be exact

-  took 3000 frames in 8-bit mode, which took around a minute. Exposure time around 3ms. Gain at 50.

- moved around the moon at random trying to find interesting features

- stacked top 200 in autostakkert using mainly default settings - some of these are 1.5x drizzle which is probably over the top, but based on comparison, doesn't appear to make a great deal of difference. Also tried stacking 100 (similar), 300 (similar), 1000 (worse) frames 

- had a go at wavelet sharpening in Registax6 - at least some of these are overdone, but it's hard!

 

I've attached 3 images I picked out of maybe 15 videos of different areas. To my eye these are both over processed in registax and still not as sharp as I'd hoped for. 

 

My next steps will be:

- try again as is, because

    - the moon was maybe at 50 degrees in the sky, around 90% illuminated, so I'll probably look for a 50% illuminated moon higher in the sky

    - there was some cloud at the end of the session so I'm not sure if this/seeing may have made for a bad night. I don't know how to measure seeing, but obviously comparing results from a few nights would be useful

- I'll probably move to the mono camera + a red or Ha filter to try to work around seeing a little more (and for mosaics - sneak a little more ROI to require less frames)

 

All  thoughts/suggestions gratefully received!

 

 

 

crater1.thumb.png.86b4654afb356435f5143b92e9d0acbc.png

 

 

crater2.thumb.png.09a3743ecbdc38d2c7185539d1f78f7d.png

crater3.thumb.png.57b94ec8ae083acb090c6b3f8e9885db.png

 

 

Edited by rnobleeddy
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They look great to me. I especially like the first one; the Schiller Annular Plain shows up really well.

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These are great! I don't think you've got much to worry about, maybe seeing could have been better and in which case the mono cam and red or IRpass filter would help. 

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Top two look pretty good. Bottom one either has some bad frames, or seeing worsened. Just keep doing what your doing. And keep experimenting like you are. Exposure ranges between 1/125th secs And 1/500th secs i have found most useful But of course many factors will influence exposure. I prefer gain around 30% 

and thats with small scopes. When i get my 10" running exposures may speed up more. But the faster you go of course, often frames will get grainier requiring more in your stacks

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I agree with the above comments. A successful first effort. Your data for sure looks good. You can give it a few tries on the processing. I personally make no use of wavelet sharpening. For some reason i never got my head around it. I use a lucy richardson deconvolution on the stacked image. Further processing in photoshop includes a combination of unsharp masks, high pass filter sharpening, camera raw filter etc. What also might help in getting more pleasing images is converting to greyscale. This will reduce any color fringing caused by atmospheric dispersion. 
 

the use of drizzle 1.5x in autostakkert! is only of use if the seeing is really good and if the raw data is slightly undersampled. With data that is already oversampled it is of no use at all. 

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6 hours ago, wouterdhoye said:

I agree with the above comments. A successful first effort. Your data for sure looks good. You can give it a few tries on the processing. I personally make no use of wavelet sharpening. For some reason i never got my head around it. I use a lucy richardson deconvolution on the stacked image. Further processing in photoshop includes a combination of unsharp masks, high pass filter sharpening, camera raw filter etc. What also might help in getting more pleasing images is converting to greyscale. This will reduce any color fringing caused by atmospheric dispersion. 
 

the use of drizzle 1.5x in autostakkert! is only of use if the seeing is really good and if the raw data is slightly undersampled. With data that is already oversampled it is of no use at all. 

Thanks - I'll try out some other options. There's a clear improvement moving from the raw stack to the autostakkert conv image to the wavelet sharpened image, but I'm far from sure I know what I'm doing in Registax, and based on the vast array of advice out there, it seems even more of an art form than other processing techniques!

 

1.5x drizzle was an accident - not sure why it was checked, but rather than do them all again, I checked and there wasn't a significant difference on a few. 

 

Good advice on converting to mono - I'll see what that does.

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On 05/05/2021 at 18:43, nfotis said:

Nice effort, I think that a different processing will give even better results.

I suggest that you simplify your processing flow as much as possible - less things to go awry this way.

N.F.

 

Do you have any suggestions? I can see that the stack is clearly better than single images, and the wavelet sharpened image is clearly better than the stack. so I guess that the obvious things are to ditch the drizzle, go B&W and perhaps tweak the sharpening in Registax?

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Personally, I didn't even use Registax, I was satisfied with the sharpening in Autostakkert!3, but that's subjective.

You can look for yourself, if you prefer this approach, or another - there's not a single definitive interpretation of these data (try different processing approaches to your data which you already captured):

 

Regards,

N.F.

Edited by nfotis
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