Jump to content

Stargazers Lounge Uses Cookies

Like most websites, SGL uses cookies in order to deliver a secure, personalised service, to provide social media functions and to analyse our traffic. Continued use of SGL indicates your acceptance of our cookie policy.

sgl_imaging_challenge_celestial_motion.thumb.jpg.a9e9349c45f96ed7928eb32f1baf76ed.jpg

ZiHao

Advice on getting sharper Moon

Recommended Posts

Hello all, back again with some moon shots and here to seek for some feedback from all!

Attached is a completed image stacked from 30 shots at ISO 640, 1/1250,processed in Registax and Photoshop and a raw image. Equipment: SW 150/750, Nikon D5300

I tried to record a 5 minutes footage of the moon in MOV format and then converted into AVI. But Registax seems to be unable to process these much of data, so I went back to stacking images instead. Does stacking frames from a video yield sharper image? I was expecting sharper results as the seeing yesterday night was good.

 

 

even2.png

DSC_0637.jpg

Share this post


Link to post
Share on other sites
Posted (edited)

In some ways I’ve found it to be six of one and half a dozen of the other. 

With video on my Nikon I have lower resolution than stills, the output isn’t raw and there’s a letterbox clipping top and bottom so if the moon is at perigee I have to process two videos and stitch. 

But, the frame rate helps ensure I capture some good frames and there’s no vibration from the shutter so I can achieve some good results, Even if the resulting image is smaller. A good Barlow or an imagemate helps here but then you have to stitch. 

Obviously for stills it’s the other way round and can be challenging for the opposite reasons. 

I tend to flip between the two depending on conditions and the moon’s phase. 

Edited by johnfosteruk
  • Like 1
  • Thanks 1

Share this post


Link to post
Share on other sites

I do like single shots rather than video myself as the whole disk wont fit when using my Mak, I do however sometimes stack three or four RAW files manually in Photoshop....

Alan

  • Like 1

Share this post


Link to post
Share on other sites
Posted (edited)

DSLR Movie mode has the most benefit it you can enable it to use centre cut-out mode. Normally the movie mode down-samples the sensor resolution to HD 1920x1080 or whatever resolution you've selected which also entails chopping off the image top and bottom to fit the 16:9 format. The movie is therefore at a lower resolution that the camera images.

In centre cut-out mode the movie uses a 1920x1080 window at the centre of the sensor and therefore no resolution is lost though the apparent FOV is of course much reduced from the full frame image. It looks like a 'zoomed' in image. You generally then need to do a mosaic to image the whole moon.

A few Canon cameras had this feature built-in though almost all are able to use it if the 'magiclantern' firmware is installed. I don't believe the Nikon firmware source code is freely available so a similar 'fix' isn't available to my knowledge for Nikon cameras.

If you're stuck with only down-sampled full frame movie mode then stacking a series of still frames (RAW not jpeg) would give you a far higher resolution final image. In fact even in centre cut-out mode, the stacked movie image would still be inferior as it is lossy compressed in MOV format anyway.

Videos of around 30s (or even less) duration are fine for the moon as 30s at 25fps will give you 750 frames. You normally use a low ISO or gain for the moon as it's so bright, so you aren't going to be struggling with noise, where a large number of frames is beneficial. Your 5 min video file when converted to uncompressed AVI could well be too large to work with if you have limited resources on your computer. I believe that PIPP is able to chop a long video into a series of shorter ones if you wish to try it. 

Stacking frames from a video won't give you a sharper initial image than a stack of still frames, even if you can use centre cut-out mode, but the lower noise attainable by stacking more images means you can apply more sharpening and other processing features to your final image without the noise becoming too noticeable. Stacking 10 or more (the more the better) still frames would always give you a 'better' higher resolution result than stacking the video. Just a single image may well be better but stacking several images enables the images with better 'seeing' to be used.

The above only refers to DSLRs due to lossy movie compression, possible downsampling, and limited frame rate. For dedicated 'planetary' cameras, videos will always give as good or better a result compared to stacking a large number of individual frames, as the videos are lossless and with a small 'region of interest' selectable, a high frame rate is attainable. Videos are just much quicker and simpler to take.

Alan

Edited by symmetal
  • Thanks 1

Share this post


Link to post
Share on other sites

I think you can do a little more work on post processing, sharpening, contrast, etc. I've taken the liberty to process one of your image's a little more and hope you don't mind. Just to show you what I mean. 

PSX_20190713_215807.jpg

  • Like 1

Share this post


Link to post
Share on other sites

Moon Post Processing is certainly an on-going thing.  For what it's worth, I have a 4k screen and the original post is bitingly sharp looking, naturally toned and pleasing to look at on a web page.  for some reason, it won't let me zoom in more.  The pic in the post above is a little overprocessed for my taste, looking a little plasticky and over-contrasty (but could be fun with a colour version with saturation overboost too).

as far as I can tell, the best way to increase detail is to get a wider aperture scope.   In the end, maths proves that detail is limited by aperture.   Then take as many shots as you can as at high a resultion as you can, as accurately focussed as you can.

I wish I had a 200 mile tall tripod!

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.