There are so many different ways how to measure the proportions of the object that you are drawing: traditional sighting/measuring, grid technique, triangular grid technique, identifying basic shapes and space, linear perspective and using basic facial & figure proportions. An artist can use any technique for life drawings, except the grid. But which way to choose when you are drawing from a reference picture when your goal is to get the most realistic and the most detailed portrait that is possible?
Nowadays the grid technique is the most popular and the easiest way to transform a photo to a drawing. In my opinion, that is the biggest mistake. An artist gets used to this technique and loses the ability of feeling shapes and spaces. And then what happens is the artist can draw only from a photo and the size of the drawing can be only the same as the size of the original picture. I believe even hyperrealism can be achieved with traditional measuring. If you want to know how, follow My Tip #3.
First, you should study the original picture, measure all the details and proportions of it. Try to examine all the parts of the face and how they are correlated, measure the distance between them, compare the size of one part of the face with another one. After that you are ready to reflect the image on the paper.
Next, start with the light shading of the shape of the face with charcoal powder without any measures, and let your eyes reflect it first the way they feel the proportions are. Then use basic facial proportions to highlight the eyes and other parts of the face. Only after that you can start transferring the measures from the original picture to your drawing. I always recommend to start with the eyes. Because the distance between the eyes is almost always the same as the size of one eye. But always remember that you don't copy the measures but you copy the correlation of the measures. That means that the distance between your drawn eyes should be equal to the size of your drawn eye, not to the size of the eye on the photo. This rule applies to all other parts of the portrait. Once your eyes are done, all the parts and the features of the face will come together step by step.
I know it sounds difficult at first. But if you manage this technique you will never need the grid and your eyes will be able to measure any object very easy and quickly. I will reveal my secret of measuring more detailed in a separate tutorial video or article.
Credit picture: Christian Steinmetz