How to Fix Sony Star Eater on the a7SII and a7RII (Continuous Shutter Mode Workaround)

Alas, a partial fix to the dreaded “star eater” issue has been found for the a7SII and a7RII! The quick version: enable continuous shutter drive mode. Read more to learn about the “star eater” issue and the limitations of this partial fix.

Sony’s a7SII and a7RII have an issue that affects astrophotography when they’re used for exposures of 4 seconds and longer. Photographs of the night sky made with these cameras (especially the a7SII) are subject to a built-in processing that mistakes stars for noise and “eats” them or reduces their brightness. The issue also affects other Sony Alpha cameras in different scenarios.

The result of the issue is an astrophoto with reduced number of visible stars and an appearance of reduced resolution in the night sky. Stars are often also color shifted to false colors as a result of the problem. Since the issue affects stars at the pixel level, the problem is especially prevalent on the relatively low-resolution sensor of the a7SII. I have documented this issue thoroughly and noted how it affects most Sony Alpha cameras on my post about the so-called “star eater” problem. With a little bit of searching, you can find many other posts about the issue across the astrophotography and photography communities that confirm the problem.

One of the best sets of analyses of the issue came from Jim Kasson’s blog posts. He shows that with a frequency analysis of a color channel on the a7RII and a7SII, exposures of 4s and longer have attenuation at higher spatial frequencies. Basically, small bright pixels are filtered out. For a long time, this has been a problem a7RII and a7SII users have had to live with for months. But now, we have Jim Kasson to thank for making us aware of a partial fix.

The Workaround

Sony a7SII Continuous Drive Mode
Star Eater Workaround: Enable Continuous Drive Shutter Mode

In a December 2017 post, Jim Kasson talked about a potential workaround on the a7RII. The fix is certainly counter-intuitive: enabling continuous drive mode while shooting long exposures. In his analysis, Jim shows that by enabling the continuous drive mode, the a7RII no longer exhibits the same behavior of the star-eating algorithm. Jim’s original analysis was only of the a7RII so I was curious to see if the same workaround would work on the a7SII. I had a friend supply some sample dark-frames from his a7SII and I took a close look at the files. Sure enough, enabling continuous mode seemed to prevent the star eater problem from occurring. I sent the frames to Jim for his final analysis of the a7SII star eater workaround which he has published here.

  • So the good news: a7RII and a7SII users can circumvent the Sony star eater issue by shooting with continuous shutter mode enabled. Either regular “Continuous” or “Continuous Speed Priority” shutter modes will work.
  • The bad news: by enabling continuous shutter mode, the color depth of the raw files is reduced to 12-bit. This means that the file is losing some dynamic range capability and may show some increase in noise. In all practicality, the results should be more desirable for astrophotography than the star-eaten files.
  • Another problem that persists: Bulb exposures are still affected because continuous shutter mode cannot be enabled in Bulb mode and vice-versa. Furthermore, the new a7RIII is still affected, regardless of shutter drive mode. 

Closing Thoughts

Why didn’t we find this earlier?

It’s extremely well hidden. Under no circumstances does usually it make sense to shoot with continuous shutter modes while shooting long exposures. Normally, it’s a shutter mode reserved for sports and wildlife shooting. There isn’t a single reason to enable continuous shutter mode for astrophotography since our shutter times tend to be very very long.

But now that it’s out, this workaround is a welcome find for owners of the a7RII and a7SII who enjoy shooting astrophotography but it’s still only a partial fix. Using the workaround, bit-depth is slightly reduced, limiting the dynamic range of the resulting photographs. It’s also unfortunate that the problem still persists in Bulb mode and there’s no workaround for Bulb shooting known at this time. Ultimately, it’s dreadfully disappointing that this issue even exists in the first place. It’s a shame that Sony still has not issued a firmware fix to allow us to disable the spatial filtering altogether. I and several other astrophotographers are supporters of the open petition to Sony to fix the star eater issue altogether.

For a more complete documentation, see my article and open letter to Sony about the star eater issue.

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47 Replies to “How to Fix Sony Star Eater on the a7SII and a7RII (Continuous Shutter Mode Workaround)”

  1. Thanks for posting this Ian. I gotta say I’m pretty upset at Sony for dropping the ball on this and not properly fixing it in their new cameras. I got the chance to try a Nikon for some astro and the ability to use bulb mode without worry convinced me that Sony was not what I needed. Having the freedom to get precise exposures feels great and also provides the means necessary to get into tracked astro.

  2. Well, I sold my a7R II based on lonely speck’s identification of the star-eating problem. Sony had taken a long time to respond and it appears they have remained silent ever since. I have had many disappointments with Sony’s nonchalance in ignoring all my emails.

    I’ve taken a huge loss in selling my Sony a7R II and lenses, I’ve decided no matter how much they improve their cameras and lenses in the full frame market or any other electronic market I will no longer be purchasing anything that has a Sony label.

    I’ve now moved to the 4/3rds platform with the Olympus OMD-E M1 Mark II and the m.Zuiko PRO lenses. I’ve yet to find out if my 9.25 inch Celestron CGE can take the Olympus M1 with an adapter.

    1. I don’t blame you, had I updated my a7s f/w, I’d likely have sold mine also but I didn’t so I’m still good to 30″. Very unlikely I’d ever buy another Sony, there are other options like the tried and true 6d (image scale be damned-hehe) which can be had for mere pennys comparatively (and you can get parts for it, and it’s compatible with all imaging software and it is not limited to 30″ and …. )

  3. With the impending release of the A7SIII ( CP+ – Camera & Photo Imaging Show /March ? ) , I would have to say – that they need to have fixed this once and for all – without any menu-manipulation, etc.

  4. As if we didn’t already have too many things to worry about (cloud coverage, remote locations, moon phase, galactic center position), now you can’t shoot in bulb mode, and have to wait for Sony to get their act together and issue a fix…

    Screw Sony man…

    1. Haha, you better stay away from real (tracked-guided) astrophotography ! (Jk)

      I agree, screw Sony, they are absolutely pathetic as a camera company with regard to any type of customer service – this issue is just the tip of the iceberg

    1. I think that good astrophotos can be made with these cameras… I still use my a7S. But the issue does make a more tangible difference for wide field photos where stars are finer. Ultimately, when compared to similar sensors on the competition (e.g. a Nikon D850, etc.), there can be some argument that the star eater issue is detrimental to the Sony cameras.

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