I'm taking oil paint class and I have trouble mixing and painting gray value correctly.
I want to make a 9-step gray scale cheat sheet to help me better mix and judge gray values. But how can I make the 9-steps "equally spaced"? OK, the black and the white are easy. What about the rest?
I don't care what media I use to make this gray scale. It could be oil paint or a computer printout. I do have an inkjet that can print deep black.
An image search on the web returns lots of gray scales. But the question remains: which one has "equally spaced" gray values? Some look like they have more dark values than others. In photoshop terms, they seem to have different gammas.
If I am able to measure exact amount of white and black paint and mix them together, does that give me the correct middle gray (value 5)? Then if I mix the same amount of middle gray with black, does that give me value 7 (black=9)?
One of the reasons art is called that and not science or math is because it is a personal evaluation of artistic sensitivities.
You could use a spectrometer to accurately measure the darkness difference between shades of gray to make an accurate grey scale but in the long run, you achieve nothing. The struggles to make a good 9 level grey scale is part of the learning. Dark shades are hard for the human eye to distinguish between. And various paints have different tinting power and a 50% mixture of black and white may not give you an exact middle value.
An exact grey scale will not make you a better painter. But trying to make one with paint will teach you to look at values and evaluate them. That will help in your painting efforts. Don't obsess over this, just do the best you can and forget the word "perfection".