Clavius region 81% waxing moon

A place to share images that you have taken with SharpCap.
Forum rules
Please upload large images to photo sharing sites (flickr, etc) rather than trying to upload them as forum attachments.

Please share the equipment used and if possible camera settings to help others.
Post Reply
User avatar
turfpit
Posts: 1779
Joined: Mon Feb 13, 2017 8:13 pm
Location: UK
Contact:

Clavius region 81% waxing moon

#1

Post by turfpit »

Captured 22nd May 2021 at 21:23, sunset was around 21:15. This was the equipment setup test ready for darkness (later session was hampered by thin high cloud).
Celestron C8 SCT, IR685 filter, QHY5LII-M camera. SC 4 beta, Autostakkert!3, Registax 6, GIMP 2.12.
Stack best 20% of 500 frames with drizzle 1.5. Registax: layer 2=30, layer 3=15.

Main craters shown are (anticlockwise) - Clavius, Maginus, Tycho, Wilhelm, Longomontanus (plus a few others):

Clavius-region.jpg
Clavius-region.jpg (756.17 KiB) Viewed 1236 times


This is the captured SER file being played back:

SER-Player.PNG
SER-Player.PNG (266.78 KiB) Viewed 1236 times

21_23_34.CameraSettings.txt
(622 Bytes) Downloaded 68 times

Dave
User avatar
Menno555
Posts: 1053
Joined: Mon Apr 20, 2020 2:19 pm
Location: The Netherlands
Contact:

Re: Clavius region 81% waxing moon

#2

Post by Menno555 »

Nice one Dave!
Btw I just yesterday found a (for me) new sharpening tool that maybe is useful for you too?
It's called ImPPG (Image Post-Processor) and it does Lucy-Richardson deconvolution and Unsharp Masking in one screen. Very easy to use and it's GPU accelerated. Info and download on https://greatattractor.github.io/imppg/

Menno
User avatar
turfpit
Posts: 1779
Joined: Mon Feb 13, 2017 8:13 pm
Location: UK
Contact:

Re: Clavius region 81% waxing moon

#3

Post by turfpit »

Cheers Menno. Thanks for the link, the software is well documented and I will have a look at it after doing some reading up on deconvolution.

Dave
timh
Posts: 515
Joined: Mon Aug 26, 2019 5:50 pm

Re: Clavius region 81% waxing moon

#4

Post by timh »

Hi Dave,

A bit of a dull technical question. Do you know how much difference to the final result is made by drizzling? My back of the envelope calculation - which may be wrong - says that your scale is ~ 0.4 arsec/ pixel which should be good to an image resolution of about an arcsec being sampled at 2.5X. If the drizzling does its job though then - sampling at 1.5X - brings you right down to the Dawes limit of the telescope at about 0.6 arcsec which is pretty impressive - and would also mean perhaps that - in theory - there would never be any point in adding a Barlow?

On a more aesthetic note it's a nice detailed fly over view of Tycho and friends. More whimsically, I wonder what size we can expect the perimeters of moon bases to be if they ever get built within the next 30 years or so and whether the type of resolution you are getting --maybe down to just over a mile or so -- might be sufficient? An extension of the hobby for future selenographers.?

TimH
User avatar
turfpit
Posts: 1779
Joined: Mon Feb 13, 2017 8:13 pm
Location: UK
Contact:

Re: Clavius region 81% waxing moon

#5

Post by turfpit »

Tim
Do you know how much difference to the final result is made by drizzling?
By comparing drizzle v no drizzle, I think the drizzle 1.5 looks 'better'. A bit subjective I know. I have tried drizzle 3 and that does not work well.

The jury is out on my 2.5x Barlow. I have never had good results with it yet but the atmosphere always seems to be against me.
I wonder what size we can expect the perimeters of moon bases to be if they ever get built within the next 30 years or so and whether the type of resolution you are getting --maybe down to just over a mile or so -- might be sufficient?

According to Virtual Moon Atlas, I have named craters which are 2 miles in diameter and I can see smaller craters on my images. I think the larger SCT's would resolve down to 1 mile given good conditions.

My main effort at the moment is to try to improve my processing of lunar images. By that I mean
  • avoiding artefacts such as small craters having 'ringing'
  • not having craters with burnt out rims
  • reducing background noise
  • avoiding the image having a 'strained' look
  • simplifying the processing steps

To this effect I am experimenting with stacking - stack 50% best frames for 5,000 frames and under; stack best 20% frames for ~10,000 frames. The image above (which was a 500 frame test capture) has been re-processed as follows:
  • Autostakkert!3 - stack best 50% of 500 with drizzle 1.5
  • Registax 6 - Layer 2 slider = 30 (nothing else)
  • GIMP - set Contrast to 30, adjust black and white levels and boost mid-tones
Registax 6 is industrial strength image mangling software unless the layer sliders are used with a 'light touch'. The minimal processing listed above (just the 3 steps) has produced this (compare with image above):

Clavius-region.jpg
Clavius-region.jpg (421.57 KiB) Viewed 1183 times


This relies on the data being good. I run with gain 30-40% and adjust exposure to give a roughly 60% saturated histogram. Hands-off motorised focusing is key.

I would like to thank Brian (@oopfan) for prodding me to do better. Lots of lunar image traffic flying between the UK and the USA yesterday has resulted in the minimal processing list described above. I will be testing the process out on some old data particularly from the Skyris 618m which can achieve 120fps over USB3.

Dave
User avatar
oopfan
Posts: 1321
Joined: Sat Jul 08, 2017 2:37 pm
Location: New York
Contact:

Re: Clavius region 81% waxing moon

#6

Post by oopfan »

Thanks for the H/T, Dave.

Wavelet Sharpening is powerful stuff, but it is too easy to cause craters to "ring". We found that it is best to pull back on the Wavelet Sharpening, and then move onto other post-processing tools like GIMP, Affinity Photo, etc. There we can experiment with more Sharpening. Affinity Photo provides "Unsharp Mask" and "Clarity" tools. I prefer "Clarity" due to its single slider control, as compared to "Unsharp Mask" having two controls. Each of these tools will not cause craters to "ring", but you still need to be careful that you don't overly saturate the sunlit side of craters. It is a delicate balance. Another thing I like to do is to boost mid-tones using "Curves". It is very effective in darkening vast lava plains while highlighting mountain ranges. Another simple technique is to play around with the black and white levels.

Sorry for the edit: Some in the audience might prefer the image in the original post (way above). That's OK if you can control how your image is consumed, for example if it were a print. However, a problem arises when people use their computer to zoom in on a digital image. They will quickly notice the unsightly "ringing" of small impact craters. (By "ringing" I mean that the crater develops two rims.) I've even seen ringing on features like Hadley Rille when too much wavelet sharpening is applied. I don't sit on the board at AstroBin, but there is a common quality to all images that win awards: for lunar there is no ringing craters, for non-lunar there is excellent guiding. This implies that one of the first tests they perform is to zoom-in on your photo. That will make or break your chances.

Brian
timh
Posts: 515
Joined: Mon Aug 26, 2019 5:50 pm

Re: Clavius region 81% waxing moon

#7

Post by timh »

turfpit wrote: Wed May 26, 2021 10:07 am By comparing drizzle v no drizzle, I think the drizzle 1.5 looks 'better'. A bit subjective I know. I have tried drizzle 3 and that does not work well.

The jury is out on my 2.5x Barlow. I have never had good results with it yet but the atmosphere always seems to be against me.
Thanks for those answers Dave -- and on the diameter of the smallest craters resolved.

It was also interesting to read yours and Brian's comments on processing - and not over-doing wavelet sharpening. The second image looks more natural.

TimH
User avatar
turfpit
Posts: 1779
Joined: Mon Feb 13, 2017 8:13 pm
Location: UK
Contact:

Re: Clavius region 81% waxing moon

#8

Post by turfpit »

Tim
The second image looks more natural.
That comment makes the hours invested in developing, testing and refining the above process worthwhile. Thanks.

Dave
Post Reply