Little Test: Pushing ISO in Post with Sony Alpha A7RII?
A short test with the Sony A7R2 for Astrophotography. What if a 800 ISO shot is pushed by three stops in Lightroom. Does it match the shot taken with 6400 ISO in camera?
The Sony A7R2 is considered as a nearly ISO invariant camera. Look here for example.
In a short test I wanted to see if I need to set the camera to higher ISO for astrophotography or if I can push exposure later in Lightroom or Capture One.
For the test one picture was taken with 6400 ISO in camera, the second one with 800 ISO and then later pushed in Lightroom by 3 stops (EV).
Here are the results.
Shot No. 1 shows some starry sky.
Shot 2 shows a darker area (the street).
My conclusion: the shot taken with 6400 in camera exhibits less artefacts. But the difference is not extreme. It's good to know that there is plenty of headroom in post, when something goes wrong.
For best dynamic range it's always good to set the A7R2 either to 100 or to 640 ISO, as shown by Jim Kasson here.