The Zone System and the Leaf Aptus-II 5

The Leaf Aptus-II 5, ISO 25, 16-bit RAW capture (14 effective), Adobe Camera Raw controls zeroed:

curve 1

Zooming in on the shadows:

curve 2

At the shadow threshold (L* = 2, about zone -1/2), the SNR is about 5.  Let us see how far down we can go and retain good shadow quality.  Setting Exposure to +1 (N+1):

curve 3

The threshold SNR at N+1 is a little low, below our desired minimum of 4.  How about N+0.5?

curve 4

N+0.5 looks good just above zone -I.  What about raising the Blacks level to improve shadow contrast as we did before?

curve 5

Let us pick Blacks = 2:

curve 6

Now for the highlights:

curve 7

So the Leafís highlights run higher than the Nikonís at the start, but are not as recoverable as the Nikonís with reduced Exposure.

Here are four zone rulers, made at N+0.5 (Shadows at 0 and 2), N, and N-1.  Good-quality print detail extends from just above zone -I to VIII 1/2, for a dynamic range of over 9 stops:

zone ruler
zone ruler
zone ruler
zone ruler
-II -I O I II III IV V VI VII VIII IX


The Nikon texture target images were very close to the same values as the gray card images; for the Leaf they were 1/3-1/2 stop darker:

N, zone O   N+1, zone -I   N+2, zone -II
N   N+0.5   N+2
L* = 2.0
SNR = 5.1
  L* = 1.9
SNR = 3.3
  L* = 2.0
SNR = 2.1
N, zone VIII   N-1, zone VIII 1/2
VIII 1/2   IX

Next:  an example