the role of the right hand fingers
I've been playing on just open strings and slow scales a lot lately so I can focus more on the bow. it made me realize that no one has ever explicitly told me what each finger is supposed to do. I learned how to hold the bow, my teachers said my bowhold was good, and that was it.
so I have a few questions and I'm happy to hear additional related comments outside of these questions:
1. how can you use the right hand fingers to get a more expressive sound? for example, I've been told to use pressure from the pointer finger to make accents, and lately I've been using it to try to get louder fortes.
2. do the middle and ring fingers have much control over the sound, or do they just help hold the bow? (that's pretty much how I've been using them, as far as I can tell)
3. is there a benefit in doing a bow exercise where you lift different right hand fingers from the bow?
4. why might my right hand feel a bit strained after trying to do upbow staccato? (it's a stroke I have basically just started learning. I use my pointer finger to briefly dig into the string and then I release. I'm not sure if this is correct.)
The mechanical role of each finger of the right hand depends on the bow-hold/school and your individual anatomy. For the popular Franco-Belgian hold each finger has a discrete job. The thumb helps control the tilt angle of the bow, and prevents the bow from falling out of your hand (!). The second finger, opposite the thumb, is the pivot point. The first finger applies leverage, force, when playing in the upper half. The fourth finger supports and controls the weight of the bow when playing below the balance point, the lower half. The third finger causes problems, use it as little possible. If you pull on the third finger the tip of the bow moves out over the fingerboard, which we usually do not want to do. Some folk fiddlers or early music specialists do not use the third and fourth fingers very much. The only time I apply extra weight and stiffen the third or fourth fingers is for on-the-string up bow staccato or down bow ricochet. Do not use the second or third fingers to help hold it up. The bow is held up at three places; the thumb, the fourth finger, and the string. There is an exercise involving lifting the fingers, but I would not attempt to describe here, too dangerous. The Russian hold feels different
May I add a slight variant to what Joel has described.
Anna you should get Simon Fischer's book "Basics". Everything you ask is explained in that book very clearly, with pictures, exercises, and everything.
If you can draw a straight line and/or have beautiful penmanship the "rules" for bow-finger use should work well for you. However, if you have any minor or major right arm/hand "disabilities" you will have to work things out differently.
The Heifetz video (a masterclass in staccato if there ever was one!) that Andrew referred to is,