Stephen Bay's Photography Blog

Star Eater on the Sony A7rii

As many of you know, Sony has a spatial filtering algorithm designed to reduce noise. However this algorithm has the drawback that it might reduce or change the appearance of stars in landscape astro shots and hence was given the name “star eater” by the community. This has been a huge issue and garned much attention online, but recently Jim Kasson discovered that it was possible to avoid the star eater effect by shooting in continuous mode for the a7r2 and s2.

So this past week, I finally got around to testing this myself. Basically I took some sky shots and then switched to continuous-high to get images without the star eater. I’ve attached some comparison images and 100% crops. Images with star eater (SE) are always on the left, images without star eater (NSE) are on the right. Taken at 25mm f/2.8 ISO 1600, 13s. Default processing in LR except +2 exposure added. Profile corrections were off.

First, here are the two overall images. There is a slight color shift between them with SE being slightly warmer and NSE being greener.

Here are 100% crops from various spots across the frame. Click on the images to open them in the browser and view them full size (they should be 1600x800px).

Finally, in the next pair the left image is the difference between two consecution shots with Star Eater on. Images aligned by manual nudging (I know this isn’t perfect). This shows how much the images differ solely due to star movement and serves as a baseline. The right is the difference between SE and NSE. This second image shows the additional changes due to switching the star eater algorithm off.

My conclusion is that it’s really hard to see any differences in the stars. The dust clouds and dark sky areas seem a bit better with the Star Eater filtering (what do you know, an algorithm designed to reduce noise actually reduces noise). Based on this test, I’ll probably not worry about it and leave SE on.