Apropos of blearily sitting at my desk drinking coffee and thinking, "wait, how do I measure out equal distances in space again" - the best $12 USD I ever spent was buying Marshall Vandruff's 1994 Perspective Drawing Series. He explains concepts SO clearly.
https://marshallart.gumroad.com/l/wbwxz
https://marshallart.gumroad.com/l/wbwxz
Comments
He does have a new perspective course with new material and notable guests coming out in parts on Proko. The catch is it's $$$ and will take over a year to fully be out. :')
$12 is an absolute steal, I'll be shoving this in my cart. Ty for sharing!
(But hopefully this series covers any of the things you're hoping to know. It truly is a steal at $1 a lesson!!)
(also it's very fun to see him back when he had hair, haha!)
$12 is a really good price, too!