When we play the same note, usually on the same string, consecutively, but with different fingers, it is called a finger substitution.
This technique is most often employed is when we want to avoid shifting within a slur. While we should be able to shift silently within a slur, it is sometimes musically more appealing, or simply cleaner, to use a finger substitution instead.
Let’s take the example below:
There are a number of ways to finger this, of course. Let’s discuss a few, including the use of finger substitutions.
For this example assume we are playing the entire excerpt on the G string.
1. We could, obviously, use a traditional fingering and just make sure our shifts are pristine and silent:
While intonation may not be an issue with the above fingering, cleanliness within the slur might.
2. We could make use of pivoting, and/or four finger technique where we would also need to be careful about the cleanliness of our pivots and shifts:
Fingering below is just one possibility using pivots.
This has it’s own set of challenges to accuracy and cleanliness, evident for most people if you attempt it.
3. Or we could use finger substitutions:
This particular fingering provides for a nearly guaranteed cleanliness within the slurs. However, we are, of course, presenting a challenge with intonation of consecutive notes. (The first two “B’s” for example.)
Finger substitutions are not cleanliness magic! However, if you are looking to clean up a passage full of shifts and slurs, or if you have even a single unfortunate shift within a slur, consider employing a finger substitution to help clean things up. It may do a passage good.