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.
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.
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.
Astrophotography 101 is a course on accessible astrophotography that’s completely free for everyone. All of the lessons are available on the Lonely Speck Astrophotography 101 page for you to access at any time. Enter your email and whenever we post a new lesson you’ll receive it in your inbox. We won’t spam you and your email will stay secure. Furthermore, updates will be sent out only periodically, usually less than once per week.
Help us help you!
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=”https://www.paypal.com/cgi-bin/webscr?cmd=_donations&business=lonelyspeckblog%40gmail.com&item_name=These+tips+help+keep+lonelyspeck.com+running.¤cy_code=USD&source=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)”
Hasn’t this issue been fixed in the newest firmware update? On Sony’s firmware update page, it states “Improved image quality when Long Exposure NR setting is OFF”. I’m really interested in Sony cameras, but if this star eater thing is still an issue, I might just stay with Canon.
One thing that I’m wondering is that do you turn off noise reduction in the camera and then process the noise out? That is how I maneuver around what I thought was a fairly minor problem anyway. Or am I totally in the blind?
It’s difficult to understand why there’s no an astrophotography mode in the menus disabling the hot-pix filter, but continuous mode will do the trick too.
Time lapse video would be easier to setup for 990 shots. In continuous mode one has to press the shutter for how long?
While the obvious thing to do is to buy a planetary or DSO CMOS camera, focusing telephotos with those cameras is complicated compared to using telescopes.
Too bad Sony gave up on the QX1, they could have made an AP version. It’s amazing how advanced the QX1 was in 2014 compared to the latest ZWO cameras – that irony is, use mostly Sony sensors.
Hi, do you know if this works with the A7s as well?
It does not work on the a7S, but “star eater” is only an issue in bulb mode on that camera. Continuous and bulb cannot be selected at the same time.
Once you have spent a couple of thousand dollars on a Sony camera, it is remarkably easy to convince yourself that the “star eater” problem does not exist, or is not important. The problem is not us, the problem is not the camera, the problem is Sony management.
I personally have wasted too many hours and too many dollars on this crap. I will never buy another Sony product.