Star Eater: Astrophotography with the a7s, a7RII, a7SII, a9 and a7RIII – An Open Letter to Sony

The Star Eater Issue: Sony Cameras for Astrophotography. An Open Letter to Sony

Sony makes excellent cameras. In the last few years, they launched a completely new full frame camera system that has pushed the bounds of digital photography. I switched entirely to Sony gear after first seeing the tremendous low-light capability of their a7S and have enjoyed many outings shooting astrophotography on many different Sony camera bodies since. I have previously recommended Sony gear to countless numbers of fellow photographers looking for the best landscape astrophotography cameras. Now, I’m hesitant to recommend Sony’s latest cameras due to a problem that affects astrophotography. Before you buy a new Sony camera, be aware of this issue. 

 

The Problem

In 2016, Sony made firmware changes to their two flagship a7 series cameras (the a7RII and a7SII). The update (believed to be 3.30 on the a7RII and 2.10 on the a7SII) was supposed to include improvements for radio controlled lighting and overall camera stability and temperature control. But hidden in these improvements is a change that affects the image quality when shooting long exposures, particularly astrophotos. The problem has been dubbed “Star Eater” by others in the astro community. The issue also affected, from day one, the original line of a7 cameras when used in Bulb mode and the problem persists through out Sony’s latest line of cameras including the a9 and a7RIII.

sony-alpha-star-eater-comparison

Full resolution examples of the “Star Eater” issue are available for download here (.zip, 8.4MB). (a7S, 30s camera timed vs 96s Bulb)

The “Star Eater” problem is a form of software spatial filtering designed to reduce noise in photos, particularly hot pixels. Unfortunately, the rather rudimentary filtering algorithm that Sony is using easily mistakes sharp pinpoint stars for noise, deleting them from the image or greatly reducing their brightness. The result is an astrophoto with less stars and the appearance of diminished resolution. Sony a7RII, a7SII and a7RIII cameras with the latest firmware exhibit this problem for all exposure times longer than 3.2″. Furthermore, the “Star Eater” issue affects RAW images (whether uncompressed or not) and cannot be disabled by any means. To top it off, it’s impossible to downgrade your firmware to a previous version. There are no user selectable settings that will prevent these cameras from eating stars.

sony-alpha-star-eater-demo

Comparison of an unaffected exposure with a “Star Eater” exposure at 100% crop. (a7S, 30s camera timed vs 96s Bulb)

The firmware change was introduced months ago but took a while to be noticed as more and more astrophotographers update the firmware of their cameras. I have confirmed the issue myself and it has been discussed and analyzed many times on other places around the online photography community, particularly on the DPReview forums, Cloudy Nights, Jim Kasson’s Last Word, and more recently on Sony Alpha Rumors.

Bad spatial filtering isn’t new to Sony’s Alpha cameras. Even with the older firmware, all recent Sony alpha mirrorless cameras including the a6000, a6300, a6500, a7S, a7R, a7, a7II, a7SII and a7RII exhibit the “Star Eater” issue when using the Bulb exposure mode (my examples above are from the a7S in Bulb Mode). Untracked landscape astrophotography rarely requires exposures longer than 30″ so I found that the issue rarely affected my photography. (Most of my exposures are made between 5 and 20 seconds.) Now, with the latest firmware updates on the a7RII and a7SII, what was once a problem that only affected the niche case of Bulb exposures now affects all reasonable untracked astrophotography exposure times (4 seconds and up).

Should you care?

Maybe. I’ll admit that it is a problem that requires a fair bit of pixel peeping. Fellow landscape astrophotographer Michael Frye has made a great analysis of what you can expect from the a7RII. All told, some photographers might never even notice the issue. But as our community shifts more and more towards the enthusiast, to the photographer who really cares about the finest capability of their equipment, an issue like this is tremendously disappointing to many of us.

Personally, learning of this change (and verifying the issue for myself) has led me to question my desire for future Sony camera bodies (it is now confirmed that the new Sony a9 and a7RIII are also affected).  It has certainly made me very skeptical of future firmware updates from Sony. Mostly, I hate the thought of having recommended a camera to so many people only to learn that something has changed that would have me question my original recommendation. These aren’t cheap tools.

sony-fe-16mm-f35-sel057fec-astrophotography-review-5

It is with great disappointment that I no longer recommend Sony cameras

The a7SII in particular is affected very greatly by this issue because of its lower resolution sensor. It was a camera that launched with praise about its low light capability and now I highly discourage you use an a7SII for astrophotography. Want to know how each camera is affected by the issue? Here’s a summary of the differences between each camera and recommendations on how to deal with it:

  • Sony a7
    • Camera timed exposures up to 30s unaffected.
    • Bulb exposures affected.
    • Recommendation: Don’t shoot astrophotography with Bulb exposures.
  • Sony a7R
    • Camera timed exposures up to 30s unaffected.
    • Bulb exposures affected.
    • Recommendation: Don’t shoot astrophotography with Bulb exposures.
    • This camera not recommended for tracked astrophotography.
  • Sony a7S
    • Camera timed exposures up to 30s unaffected.
    • Bulb exposures affected.
    • Because of the lower resolution sensor (12MP), star eater issue for Bulb exposures is significantly more apparent.
    • Recommendation: Don’t shoot astrophotography with Bulb exposures.
    • This camera not recommended for tracked astrophotography.
  • Sony a7II
    • Camera timed exposures up to 30s unaffected.
    • Bulb exposures affected.
    • Recommendation: Don’t shoot astrophotography with Bulb exposures.
    • This camera not recommended for tracked astrophotography.
  • Sony a7SII
    • Camera timed exposures longer than 3.2s affected.
    • Bulb exposures affected.
    • Because of the lower resolution sensor (12MP), star eater issue is significantly more apparent.
    • Recommendation: Use longer than recommended exposure times to increase star trailing to reduce the effects of star eater. Don’t shoot astrophotography with Bulb exposures.
    • This camera not recommended for tracked or untracked astrophotography.
  • Sony a7RII
    • Camera timed exposures longer than 3.2s affected.
    • Bulb exposures affected.
    • Continuous Low and High modes are a potential workaround, but with a reduction to 12-bit color depth.
    • Recommendation:Don’t shoot astrophotography with Bulb exposures. The issue can be partially hidden by this camera’s higher resolution sensor. Use longer than recommended exposure times to increase star trailing to reduce the effects of star eater. Use Continuous High or Low.
    • This camera not recommended for tracked astrophotography.
  • Sony a9
    • All timed exposures affected.
    • Bulb exposures affected.
    • Recommendation:Don’t shoot astrophotography with Bulb exposures. The issue can be partially hidden by this camera’s higher resolution sensor. Use longer than recommended exposure times to increase star trailing to reduce the effects of star eater.
    • This camera not recommended for tracked astrophotography.
  • Sony a7RIII
    • Camera timed exposures longer than 3.2s affected.
    • Bulb exposures affected.
    • Shows very slight improvement over a7RII but still apparent.
    • Recommendation: Don’t shoot astrophotography with Bulb exposures. The issue can be partially hidden by this camera’s higher resolution sensor. Use longer than recommended exposure times to increase star trailing to reduce the effects of star eater.
    • This camera not recommended for tracked astrophotography.

It is with great disappointment that I hesitate to recommend Sony cameras, especially the a7SII which could have been an amazing astrophotography camera. There are ways to deal with the issue depending on the camera you are using. Most of the time, a longer than recommended exposure time, which will cause the stars to trail, can help hide the issue by stretching the appearance of the stars past the threshold of the spatial filtering algorithm.

If you’ve shared the same love of Sony cameras as I have in the past, and you own one of these cameras, help us reach out to Sony directly by calling Sony at:

Sony support hotline: (800) 222-7669
Sony alpha technical team: 1-239-245-6360

Please reference this article at: lonelyspeck.com/stareater

Sony introduced the problem with firmware. They can fix it with firmware. If enough of us call, maybe we can get them to issue a fix.

 I have already started reaching out to Sony directly as well as writing to several of my contacts close to Sony to see if we can get some action. So far, Sony has not responded to my initial emails and many other photographers have experienced the same lack of response. I think that the only way to get a fix is to keep trying to contact Sony. If you have contacts at Sony, any help reaching out to them would be greatly appreciated by me and many others.
I will update this blog post accordingly if I see any significant progress.
My open letter to Sony is a re-writing of this blog post and is published below:

Hello Sony, 

I am writing with great concern about the so-called “Star Eater” problem affecting Sony Alpha cameras. 

Most of the latest Sony Alpha cameras employ a spatial filtering noise reduction algorithm when using Bulb mode. This noise reduction targets hot pixels. It affects RAW files and cannot be turned off, even when using Uncompressed RAW. The primary issue with the spatial filtering is that it greatly affects astrophotography: dimmer stars that occupy only a few pixels are erased, essentially “mistaken” for noise by the filtering algorithm. The result is an astrophoto with greatly reduced visibility of dim stars and an overall appearance of reduced resolution. 

This issue affects all recent Sony alpha mirrorless cameras including the a6000, a6300, a6500, a7S, a7R, a7, a7II, a7SII and a7RII. It likely affects more models, too. The issue has been thoroughly discussed and analyzed by others in the community, particularly on the DPReview forums and on Jim Kasson’s Last Word blog. References are at the bottom of this email. 

My blog, lonelyspeck.com, focuses specifically on accessible landscape astrophotography for beginners and I’ve personally been a big fan of Sony cameras up until now. While the spatial filtering on Sony Alpha cameras has been documented for a long time, it didn’t really affect the simpler forms of astrophotography that do not require shutter times longer than 30s. If we used these cameras in M mode and let the camera time the exposure up to 30s long, the camera would not apply the problematic spatial filtering. For most cases in landscape astrophotography, night sky exposures almost never exceed 30s in order to reduce star trailing. 

But I’ve recently learned, particularly through some emailing with readers, Sony Alpha Rumors, as well as the DPReview forums and Jim Kasson’s blog, that Sony has issued firmware updates to at least the a7RII and a7SII (3.30 and 2.10, respectively) that now forces the same “Star Eater” spatial filtering on all exposures that exceed 3.2s in shutter time, even when not in Bulb mode. What was once a problem that only affected the niche case of Bulb exposures now affects ALL reasonable untracked astrophotography exposure times for common focal lengths. 

Personally, learning of this change (and verifying the issue for myself) has led me to question my desire for future Sony camera bodies and has made me very skeptical of future firmware updates. I hate the thought of having recommending a camera to someone only to learn that something has changed that would have me question my original recommendation. These aren’t cheap tools. As a result, I’m no longer recommending and will be forced to discourage the use of current and future Sony cameras on my blog, unless we see a fix. 

I’m reaching out because I believe Sony has the capability to fix this issue to win back the support of so many loyal fans. We have already seen Sony make improvements and fixes to the a7 series when DPReview published about the original issues with Sony’s compressed RAW artifact problems. As a result, Sony issued firmware updates for the a7II, a7SII, and a7RII that enabled uncompressed RAW.  It was a fix that was favorably commended by many in the photography community. Now, we need another fix.

Sony, please fix the “Star Eater” spatial filtering issue via a firmware update… the problem was introduced/exacerbated with firmware so it’s obvious it can be fixed with firmware. At the very least, make it a selectable option in the menu such that it can be disabled when desired. Adding the option to disable it for Bulb mode would just be icing on the cake.

This letter is available publicly as a blog post on lonelyspeck.com, documenting the issue for my readers. I’ve recommended the a7SII and a7RII to so many people for landscape astrophotography and it would feel disingenuous to not tell them about this issue. 

For reference, here are a number of online sources that discuss the “Star Eater” problem:

DPReview:

https://www.dpreview.com/forums/post/58709160
https://www.dpreview.com/forums/post/55841466

Cloudy Nights:

https://www.cloudynights.com/topic/498339-sony-a7s-star-eater-algorithm/
https://www.cloudynights.com/topic/505754-another-real-world-example-of-sonys-star-eater-problem/
https://www.cloudynights.com/topic/558230-star-eater-in-action-sony-a7rii/

SAR:

http://www.sonyalpharumors.com/specific-a7sii-astrophotography-fix-request/#disqus_thread

Sony Community: 

https://community.sony.com/t5/Alpha-NEX-Cameras/Star-eater-in-bulb-mode/td-p/508740

From Jim Kasson: 

http://blog.kasson.com/the-last-word/spacial-filtering-of-raw-images-by-sony-a7s-a7ii/
http://blog.kasson.com/the-last-word/sony-a7rii-long-exposure-spatial-filtering-with-fw-3-30/
http://blog.kasson.com/the-last-word/16486/
http://blog.kasson.com/the-last-word/lenr-and-sony-a7rii-fw-3-30-lowpass-filteering/
http://blog.kasson.com/the-last-word/reverse-engineering-the-sony-a7rii-long-exposure-spatial-filtering/
http://blog.kasson.com/the-last-word/sony-a7rii-bulb-spatial-filtering/

Sincerely, 

Ian Norman
[email protected]
lonelyspeck.com

UPDATES

UPDATE, May 4, 2017: Rob Shelley of Sony Pro Services has responded with the following message:

Ian, your Star Eater post was forwarded to me by a reader. Great insight that I will pass along to Engineers for developmental consideration.

As you noted, replies from Sony are not frequent but are often heard. Feel free to, if you have other comments, forward them along to me and I will get them to the appropriate departments and individuals.
Contact me any time by phone or email.

All the best.
Rob Shelley
Pro Services Support Manager Southwest
Sony North America

UPDATE, May 4, 2017: I received the following reply from Trung Vu of Sony Alpha Pro Support:

We have forwarded your concern to our sustaining engineering group.

Trung Vu
Senior Product Specialist
Sony Alpha Pro Support

UPDATE, May 5, 2017: I spoke with Rob Shelley of Sony Pro Services on the phone. He has informed me that he will try to contact the relevant parties in engineering about the concern. That said, it seems as if he was never previously aware of this issue and is not fully sure of what needs to happen next for a fix. I hoping that he will take this matter seriously and find the right people in order to forward our collective concern.

UPDATE May 6, 2017: I and several others have received the following generic reply from [email protected]:

We’re sorry to hear that. To best assist you regarding this concern, please call our alpha support team.

Sony support hotline: (800) 222-7669
Sony alpha technical team: 1-239-245-6360
Business Hours:
Monday – Friday 8:00 AM to 12:00 AM ET (Midnight).
Saturday – Sunday 9:00 AM to 8:00 PM ET.

We look forward to your continuous support to Sony products.

Regards,
Anthony
Sony Social Media Team

UPDATE: May 30, 2017: The Sony a9 does it.

 

UPDATE: June 13, 2017: I can confirm now that the latest firmware updates (4.00 for the a7RII and 3.00 for the a7SII) do not change the behavior of the cameras in any significant way. Jim Kasson did a great technical analysis of the issue with the latest firmware. So basically, this update was a false alarm. I received help from several of you to come to this conclusion, thanks for sending me your RAW files. I’m going to be relaying the latest to Sony Pro Support and hoping that they can help continue to get the message to the right people to see a fix through.

UPDATE: July 28, 2017:

PLEASE SIGN OUR PETITION TO SONY.
Thanks everyone who has been trying to contact Sony. Keep calling. This isn’t fixed yet. –Ian

UPDATE: November 21, 2017: Sony’s newest camera yet, the Sony a7RIII is also a star eater (dpreview). I’ve chatted via email with Rishi Sanyal of dprevew.com and reviewed file samples from Drew Geraci (despite his conclusions) and I can confirm that the a7RIII also eats stars for exposures 4 seconds and longer. Dpreview’s comparisons show a small improvement versus the older a7RII but it’s clear that there is still spatial filtering being applied to long exposure raw files. The biggest problem of course still remains on the a7SII where the issue isn’t as easily “hidden” due to the camera’s lower resolution 12MP sensor.

UPDATE: December 28, 2017: Jim Kasson has written about a possible workaround on the a7RII by using “Continuous High or Continuous Low” modes.

259 Responses

  1. Astrocat June 28, 2018 / 2:50 pm

    Has been the problem fixed?

  2. Miguel June 28, 2018 / 4:23 am

    Bravo for sony…i own an a7 ll and a6300 and i was thinking to buy an a7sll but im going to park the buy….if sony solve the problem…may be go againg with the purchase…thanks sooooo much Ian for yor investigation..and hepl….come soon to my home in Spain for a free lunch..!

  3. Thomas June 24, 2018 / 3:06 pm

    Is this also an issue with the a5100?

  4. Mohan June 12, 2018 / 7:26 pm

    Is this still an issue as of June 2018?
    I just bought the original Sony A7 (as it is the only FF in my budget).

  5. A7 fan May 20, 2018 / 3:14 am

    Hello everyone just wanted to confirm that Sony A7II seems to be affected by this issue even with short exposures such as 8sec exposure.
    The pictures look like they are effected and dimmer stars are removed from the picture. Compared to the Canon 6D the difference can be felt I moved to Sony recently so I can compare the two cameras, Sony files look too clean and the first thing I notice going trough the files are the very unnatural looking star formations in the picture, it looks exactly the same as in the GIF file you added in this article.
    So I though that the problem only occur in BULB mode, but it seem that it is visible with short exposures also…

    PLEASE BE AWARE OF THE ISSUE GUYS.

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