[HN Gopher] Is Astrophotography Without Tracking Possible?
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       Is Astrophotography Without Tracking Possible?
        
       Author : astroimagery
       Score  : 17 points
       Date   : 2025-05-21 10:22 UTC (3 days ago)
        
 (HTM) web link (astroimagery.com)
 (TXT) w3m dump (astroimagery.com)
        
       | incomingpain wrote:
       | Tracking is needed for when you want to do say 15 second
       | exposures.
       | 
       | The new technique for astrophotography isnt long exposures. Its
       | about fast exposures in an attempt to maximize good atmospheric
       | wobble.
        
         | astroimagery wrote:
         | That's called lucky imaging, yes. It's not particcularly new
         | btw. Also, for capturing very faint deep sky objects like
         | galaxies and nebulae you need long exposures of several minutes
         | to get the deeper detail.
        
       | pppone wrote:
       | Yes, and it is already happening in professional astronomy. For
       | example, the "Antarctic Tianmu Plan" [0] have shown that you can
       | successfully capture non-trailed images without using tracking
       | mounts by using drift-scanning CCDs--basically letting the sky
       | move across your sensor while the detector is read out at the
       | same rate.
       | 
       | [0] - https://doi.org/10.1117/12.3019468
        
         | madaxe_again wrote:
         | You _can_ , but dark noise is a problem with this technique as
         | your SNR per bucket ends up being low. The purpose of long
         | exposures with tracking is to maximise your SNR.
         | 
         | Also, it helps significantly to be in Antarctica, where the
         | relative movement is much slower than it is at lower latitudes
         | -- and to have multiple telescopes - and low noise CCDs, in a
         | cold, dry environment.
         | 
         | Sadly, most of us don't have those luxuries.
        
           | dr_coffee wrote:
           | what about computational methods? i have always wondered how
           | stacking many short exposures without tracking compares to
           | deconvolution of a single long exposure. it seems that there
           | is software able to do this by taking into account both
           | motion blur and the PSF of the imaging system:
           | 
           | https://siril.readthedocs.io/en/stable/processing/deconvolut.
           | ..
        
       | hengheng wrote:
       | Nowadays, most people who say astrophotography don't mean Deep
       | Sky photography, hunting planets, nebula and galaxies. It's
       | mostly the sky over a wide-angle landscape. "Astrophotography"
       | happens at < 20mm.
       | 
       | Totally viable untracked. The classic 14mm prime has gone from
       | f2.8 to f1.8 to f1.4, and sensors have become really good at high
       | sensitivity for a 15 second exposure. Quite often, that's enough.
       | 
       | The hairy part is when it's not quite enough, and exposures have
       | to be stacked. I have a crop sensor camera (canon 1.6x, so 40%
       | area) with an f/2 lens that I like to step down further, and a
       | good Starscape this way will take 10-40 exposures. I can stack
       | those no problem, but it's trees on the horizon that are
       | problematic. The ground stack and the sky stack have to clash,
       | and a complex shaped border will always look photoshopped,
       | because it is.
       | 
       | Old school Deep Sky is losing its appeal due to a) pictures being
       | available online, meaning that you've already seen the better
       | version of the same photo, and b) the images being sterile and
       | without context, with no relation to the photographer's story.
       | Milky Way in a national park says "I've been there!" in a way
       | that a shot of the Whirlpool Galaxy just can't.
        
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       (page generated 2025-05-24 23:00 UTC)