This is one in a series of posts on the Fujifilm GFX 100S. 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 “GFX 100S”.
In this post, I showed you histograms for a series of dark-field images made with the GFX 100s. A reader requested that I look at the histograms when the camera is set to 16-bit precision. Hence, this post.
I made images with the body cap in place under the following conditions:
- 1/1000 second
- 16 bit
- Lossless compression
At ISO 100, we see some combing in the first green channel histogram. I’m not sure what’s going on there. One of the third from the LSB transitions is a bit wider than it should be. The black point is about 256.
At ISO 160, we see the same first green chanel combing, and also the same blue channel peaking that I attributed to PDAF pixel interpolation in the first set of histograms. The blue channel black point seems to have shifted a bit lower.
At ISO 200, the black point changes to about 4096.
ISO 400 is the highest ISO with the low conversion gain. Some combing is emerging in the second green chanel histogram.
ISO 500 is the lowest ISO setting with high conversion gain, and the change in conversion gain results in a decrease in the read noise.
At ISO 1000, the combing in the first green channel disappears. It’s obvious that there is some kind of signal processing in the second green channel.
At ISO 4000, the red and first green channel histograms look perfectly normal. The interpolation is evident int he blue and second green channels, and the black point has shifted a bit higher in those channels.
At ISO 8000, the second green and blue channel back points have shifted even higher.
At ISO 10000, the black points of the second green and the blue channels have shifted to less than their nominal values.
Same at ISO 12800.
At ISO 25600, the noise is so great that the interpolation spike is widening.
At ISO 51200, The interpolation spike is now just one-bucket wide.
This has been an interesting exercise. It remains to be seen how these results relate to real photography.