Trill measure 29 3rd movement moonlight sonata

Question

How do you play the trill in measure 29 of Beethoven's moonlight sonata?

Answer 1

I would play it like this (the image came out kind of big...):

You can play the lower A# quite short to avoid tension (if it suits your interpretation, of course). For me the most natural fingering is 4-5-4-3-4-5 in the upper voice, although 3-5-3-2-3 works, too, and might be easier if your hand is big and/or 4th finger weak.

There's a similar trill a couple bars later, which I find much harder. The fingering 4-5-4-3-4-5 works there, too, or you may try 5-3-5-3-5-4 or something similar. In both cases it helps to play the first note of the trill a bit longer and stronger than the others, and it works musically, too.

Answer 2

Beethoven always started his trills on the upper note (documented here), unlike modern practice. This would come out more fluent coming onto the G#. Although Nonpop's example could work, it's not normal to start and end on the same note. A better interpretation would be B A# B A# G# A#. As far as fingering, without context, it is hard to say what would work best, but 4-3-4-3-2-3 should work. As far as timing, whatever goes with your interpretation is fine. I've shown two alternate timings below.