tilted views

When you draw the smaller circle (2/3 diameter of the larger) at this angle, it is of course an ellipse, but imagine slicing it across its middle and continuing this around your circle to find the brow line. The base of the nose and ear will still be at a similar level around the circle, but because of the foreshortened perspective, the distance which would be equal thirds from hairline to brow to nose base to chin tip would in fact be successively smaller from chin to hairline

Here (in extreme angles) is where the Loomis method (circle/ ellipse) method gives more help to learners than the oval method.

The foreshortening of the horizontal oval makes it almost a circle anyway. (in the oval method you are estimating the foreshortening). What is important to remember in any approach is that the proportional distances gradually decrease going back (10 to 0) instead of being equal as in the frontal view.

(tilted down view next page)

Here is another method for those tricky tilted-back views. Draw a side view of the head, tilt it back 45 degrees, and using horizontal lines you can position the hairline, eyebrows, nose, chin, ears etc and fill in the rest. Make sure to use curved lines from the side edge, see the difference below, note how the face looks flat.