I'd like to add a bit to explain my enthusiasm with this "progressive focus" method, just a little further.
For years I tried everything I had heard, and read, regarding the painting of a portrait. I created precise drawings, preliminary sketches. I used gridding, tracing, projecting, and literally "winging it", all to no avail. With all this information regarding methods of creating a portrait that represented a relatively accurate likeness of the individual model, I failed in my attempts at creating such a portrait. I could not seem to attain a likeness.
In fact, one of the absolute worst
portraits I ever accomplished was the result of my having become entranced with that which I call the "classic proportion" approach. This involved the spacing of the elements of the human face as proposed by those who primarily paint portraits from imagination, I believe. This sort of approach is dictated by those who feel that eyes should be spaced a predetermined distance apart, that the head needs to sectioned off in convenient pieces, and that features of the human face are somehow to be placed at specific distances from one another.
This approach may succeed if one desires to paint a portrait of a recognizable, human being from pure imagination, but it falls flat if your goal is to represent the specific features of your favorite aunt, grandma, or son. It just does NOT work. People simply are not constructed like the Greek gods after whom this "classic proportion" approach has been designed. The simple fact is that ....people are not (hardly ever) built with the elements of their face features to specific proportions. There is one professional wrestler on TV whose eyes are so close together that they nearly appear to be overlapped! And, when attending a school function a one time, I noticed an Asian girl whose eyes were so far apart that one could have squeezed in THREE eye widths between them! No, people are NOT built the same!
Somehow the good ol', artist method of "paint what you see" seems to give 'way to the "paint what you think ought to be there", or the "paint what you know" approach, when portrait teachers get 'hold of it. I never could quite understand that reasoning.
Long story short, when I tried this progressive focus method for the first time, I figured it would be just another desperate attempt that would result in failure for me to capture a reasonably accurate likeness of the person being painted. Since I did not have access to all the back-lighting, rear-projecting, equipment that Rob Howard used in his demo on the Cennini Forum so many years ago, I just created a series of progressively-blurred images of the same subject, so that I could use them as my reference photos.
I use a reference photo (or really, a blurred series of them) that is the exact proportion to the canvas size that I'm going to use for the portrait.
The first time I tried this progressive blur approach, I achieved my first really accurate likeness of my model. Believing that to be a fluke, I immediately did another portrait, only to discover that the method actually worked, and I turned out another relatively accurate likeness of my model. And, all this with no preliminary drawing, sketching, or proportioning, whatsoever.
In the interim, I sadly drifted back to using some sort of "preliminary drawing" technique, for which I was once again "rewarded" with the same disappointing lack of likeness, which had plagued me before I discovered this progressive focus method. So, I discarded this method that had served me so poorly, in favor on my new progressive focus method that had actually worked!
At present, I remain sold on the progressive focus method of painting a portrait, and I am convinced that the way I experience my best success is when I begin such a portrait with a "I don't care how this portrait is going to look" attitude at the onset. It seems the more careful my preliminary work is on a portrait, the worse it looks in its final appearance, whereas when I truly don't care how it will appear, my best work emerges.