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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Lonely Speck is my full-time job. It’s been an amazing experience for us to see a community develop around learning astrophotography and we’re so happy to be a small part of it. I have learned that amazing things happen when you ask for help so remember that we are always here for you. If you have any questions about photography or just want to share a story, contact us! If you find the articles here helpful, consider helping us out with a donation. [button font_size=”16″ color=”#136e9f” text_color=”#ffffff” url=”” target=”_blank”]Donate[/button] Thanks so much for being a part of our astrophotography adventure. -Ian

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

  1. I’d be curious to know about the A7rIII, as well. I have one along with the 16-35mm 2.8 GM. What say you, fellas? I think one of us needs to step up to the plate and take some sample images. I’d go out tonight and do it myself if I weren’t suffering from the flu from hell and if it weren’t -28C outside tonight.

    1. My thinking is that the issue should also be mitigated by using a slightly longer focal length. I was thinking of picking up the Tokina 20mm f/2 or the Rokinon 20mm 1.8. Being a slightly tighter frame, it should help keep a lot of those smaller stars above 1 pixel in size and avoid the worst of the spatial filtering. It’ll reduce the exposure time a little bit, but the extra stop over my 16mm 2.8 more than makes up for that.

      I contemplated getting a D750 to use as a dedicated astro camera, but then I thought, “WTF am I doing?” I don’t shoot astro that much, though I do enjoy it quite a bit. Sinking all that extra money into another camera system that I’d only use a few times a year seems silly. Come May, I’ll head out to shoot the stars, see what I get. Though the A7rIII isn’t ideal, if it’s good enough, then I’ll take it.

      Thanks Ian!

  2. Thanks a lot for this insightful analysis. I’ve just set up my Sony NEX-6 for AP and was about to do my first shots (as soon as the clouds clear). Should I anticipate the same problems with it?

    1. The NEX-6 is a different generation of camera and may not have the same issue. I have not personally tested it.

  3. Would this also work in the ‘Self-timer (Cont.): 2 sec. 5 img.’ mode? That is my preferred astro mode as It will take all 5 shots with an equal amount of time between them. Then I can stack them all later.

  4. Hi Ian,

    Thanks for the heads up on this work around for the star eater issue on the A7rii. Although you state “There isn’t a single reason to enable continuous shutter mode for astrophotography since our shutter times tend to be very very long”, I have found that for stacking Milky Way images for SLS, setting my A7Rii to 8-10 second exposures in continuous mode is an easy way to capture the 8-16 exposures I need for stacking. From what you have indicated in this post, I apparently been mitigating the star eater issue, without even knowing I was doing so! Thanks for the info.

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