This is the 67th in a series of posts on the Nikon D850. You should be able to find all the posts about that camera in the Category List on the right sidebar, below the Articles widget. There’s a drop-down menu there that you can use to get to all the posts in this series; just look for “D850”.
Yesterday, I darkened the sky with graphs relating to the Nikon D850’s noise and how that relates to the ISO setting in the camera. Today, you’re going to be able to ignore the numbers and focus on visuals.
I made a series of images of my standard subject for this test all with the same shutter speed, using an Otus 55/1.4 set to f/4, at ISOs 64 through 320 in 1/3 stop increments. The exposure I chose was ETTR at ISO 320, and thus quite a bit underexposed at ISO 64. I processed them all in Lightroom with default settings except for a custom white balance that assured that the WB wouldn’t change from image to image. Here are the full-frame images from the beginning and end of the series.
Then I boosted Lightroom’s Exposure control by an amount that compensated for the underexposure. Since each click on the Exposure widget in the Library window is a third of a stop, this was easy to do. I looked at the noise in each image. It turned out that the changes were subtle to the point of silliness, so I’ll just show you the two endpoints again, magnified to about 200%.
There is a small difference in favor of the ISO 320 image, but not one that would affect normal photography.
Searching for differentiation, I applied a +100 shadow boost to both images:
The biggest difference is that Lr’s tone curve in the shadows causes the tone mapping of the images to be different. The noise differences are somewhat more apparent, though.