Pinky on left hand and right hand question
I have a few questions that I hope can be answered:
1. Is it okay for my right hand pinky to be dangling off the bow instead of on it? Why is it bad or okay to do so?
2. Is it okay to do a trill on the left hand with a pinky? Or is it better to avoid it and to shift up/down to trill with the middle finger instead?
1: Noooo. You will lose all control of your bow.
Some players have bow holds where the pinky floats off pretty naturally. It depends on your overall hold and right-hand technique whether or not that works for you.
Fourth finger trills, if they are fast enough, helps in a few spots.
An excellent pro violinist (and dear friend) heard me perform one time. Afterward he pulled me aside and told me (paraphrasing): "Paul, you're letting your pinky off your bow and you shouldn't do that." He explained why I need it to be there for control and how I need to get in the habit of it now because later I'll learn more subtle bow strokes that will require it, etc. Then I heard him perform in a chamber group and I watched him closely. His pinky stayed on his bow, pretty much all the time -- his is quite a standard Franco-Belgian hold and his hand looks unbelievably relaxed.
@Cotton, "Most people have a terrible fourth-finger trill".
Mandolin worked very well for me for 4th finger strengthening, it still took years to build up strength and dexterity on the mando. I credit mandolin with curing trigger-finger on the left-pinky too.
1. I've seen Perlman videos where his pinky is rarely on his bow. How you use your ring finger affects how much you need your pinky.