Today it is common practice among photographers to use Ansel Adams' zone system to deliver a balanced photo. It was a rule he followed to make sure there was detail in every part of his work and, in his “analog” world, the print he produced. To quote his book “The negative”: To arrive at that scale, he first created middle grey zone 5 and continued from there. He further explained that clear texture, however, is from zone 2 to zone 8. He wrote that dynamic range is from zone 1 to zone 9. A print was made of each zone, 11 pieces, from zone 0 (black) to zone 10 (white). Something like this posterized gradient:
Figure 1: Posterized gradient
The digital photographic age has come, the zone system still in use, but on our screen it looks different from what AA saw in his dark room. Light is gradual and this is how we create a dark to light gradient today.
To create a full scale of zone masks today there are a lot of actions on the market, also you can easily create your own set like I did. (at least that way I have the freedom to create the LM I really need in my workflow)
On the website from Tony Kuyper (he was the first ever to create LM), in his blog, you can find in detail how to do this.
When I create a new document in Photoshop and draw a gradient, this is how it looks:
Figure 2: zone masks one a linear gradient