How to change position ( from high to low ) on the violin
Some people say that left hand technique begins with shifting or changing position. The more commonly known features about shifts are that they must be light, smooth, methodic, constant, and executed at the right speed. Also, this movement should be expressive. By this I mean that when returning to first position from 4th, for example, one must not keep hand and forearm fixed and immobile ( with respect to each other ). Instead, the wrist ( simply the angle between hand and forearm ) must undergo a smooth and gradual change, as the back of the hand ( together with the thumb ) leads the movement, slightly in advance of the forearm. This produces a slight backward bending of the hand, ( the base of the hand, or wrist will appear to point towards one's face ) as one shifts down. The purpose of this "sophistication" is to give the movement more expression and feeling in the joints. It will help to smooth the shift, and keep it light, and will also greatly reduce the danger of a jumpy slide, or one that stutters, instead of caressing the strings on its downward journey.
This technique is not superfluous ; it is necessary. Imagine a détaché without any wrist action... it would be pretty stiff, wouldn't it ? Well, the same is true of the left hand ; by adding a little flexibility, one avoids the stiffness that would come about by a simple thrust back of the hand. Lastly, to convince my readers, I will point out that the top violinists actually do this movement as described. It is simply not visible until one points a high-speed camera at it. Also, in real life, the movement may be so subtle and hidden, that it is difficult to notice. I have seen it clearly in high speed clips of Heifetz's left hand as he performed complex left hand passages.
The best way of practising this downward shifting, is to practise the shift very very slowly...yet maintaining order, lightness and smoothness above all else. One must play, sing and listen to the portamento ( the slide ) to see if it describes a truly constant and undisturbed motion downwards ! Listening to the regularity ( or non ) of the slide will tell you if the pressure and smoothness are reaching a high enough standard. It is a fact that almost all student shifts and changes of position are executed with roughness, too much weight, and too suddenly. A deft shift will look very calm and undisturbed... it will be executed with a cool air of softness and might even look as if seen in slow motion.
Animation of correct movement : Notice the thumb movement. Notice the bending of the wrist as the shift terminates in first position. The slight jerkiness of the video is due to the low resolution it is presented in. All shifts should be as smooth as silk.
images/movies/shiftinginter2.wmv