Do you have a rule of thumb about how small a head can be before getting a likeness becomes very difficult? Does this change for different media?
I'm working on a drawing of some friends at work. I cropped and toned the image to my liking but I've discovered the heads are just on the edge of being too small to get a decent likeness. They are 6cm or 2 1/4 inches from bottom of the chin to top of the head.

Comments
The is no size limitation other than skill level. Practice, practice, practice...
On a smooth A2 panel the head is around 60mm in diameter.
An important dimension as this is what determines the proportions of the body. This ensures that the feet are off the page
For a standing figure I break the vertical dimension into ten parts. This comprised an eight heads proportionate figure with a one unit space top and bottom. So it is easy to calculate head size.
Denis
edit: fixed an arithmetic error on line 10.
My question was more of a general one, wanting to pick your brains to sidestep future trouble for myself and any other Newbies out there.
From this drawing I now have a composition rule of thumb saying 'for pencil, 6cm is getting a bit small for a head at the moment'.
For those who have painted portraits, how would you complete this sentence 'for a DMP style painting, ???cm or ??? inches is getting a bit small for a head'.
@dencal thank you for your input and table. Very informative. Are feet tricky then? It surprised me how quickly a portrait or figure can eat up a canvas!
@KingstonFineArt I have kept your words in my head as I worked today. I've played with a few things and they seem promising. I do enjoy the dark side of graphite though😉
@oilpainter1950 and @tassieguy thanks for your encouragement.
Denis
@allforChrist fingernail... FINGERNAIL! That's seriously impressive and backs up what @KingstonFineArt said. I certainly need more practice and guidance.
@MichaelD one more 'joke' like that and you can join @dencal in detention!
Please do not waste time, pencils and mental health on manual or electric sharpeners.
Have a look at my thread on Easy Long Points.
https://forum.drawmixpaint.com/discussion/6566/pencils-easy-long-points
Denis
"Two of my greatest enemies in painting in realism are, boredom and apathy. "
I have reached my BandA limit on this artwork and I've posted the 'finished' piece in the Drawing thread.