During the show itself there was so much to look at in Zeffirelli's magnificent staging that I couldn't tear my eyes away from the sets, with the cast of 240 extras, plus a donkey and a horse, in the streets of Paris during Act 2. Plus it was too dark on my sketchbook page to see much of what I was doing.
But during Act 3 there was enough spill light from the stage to jot down quick silhouettes of Mimi, as performed by Romanian soprano Anita Hartig.
The portrait of the cellist at the lower right was sketched in extremely dim light, so that I couldn't make out any details. I could only state basic planes of light and shadow, using water-soluble colored pencils and two water brushes, one filled with water, and the other with fountain pen ink.