Moderndandy wrote:...with a Renaissance Lute... I'm trying to learn the thumb out technique (which I know most use the thumb under) but I'm having trouble being comfortable resting my little finger On the soundboard. I can play fine without doing it but know I'm supposed do. Do I have to? Will this cause problems if I don't?
No, it will cause no problems if you don't, especially if, as you say, you "can play fine without doing it". So don't worry about "supposed to"-- unless you have some professional aspirations that may be affected by how the Historical Authentics may view and remark upon your technical style.
But, setting aside "supposed" and "have" to, you might investigate it enough to give it a chance. Paul O'Dette, in this interview...
... demonstrates and describes the technique. For him, and players like him, the little-finger-resting has a positive function in their approach, and is not the negative restraint that it would seem to be to others, myself included. There is no doubt that he and others achieve stunning results. I would do much more than the proverbial "walk-across-the-street" to hear him play. He is absolutely great. So, the example is not one casually to be dismissed.
However, the rather dire consequences of wildly uncontrolled action he would ascribe as resulting from not
so resting the little finger do not necessarily follow as an inexorable result.
The control issue spoken of is purportedly in the use of thumb alternating technique, the forearm up-and-down action of which lute players continued as an application derived from earlier use of plectrums. In the first of the above, the thumb alternating technique is in the quick melodic interjections near the end of the piece, in the second, you get a closer look (the thumb alternation in these is "p-m", not "p-i").
Here, there is no little finger planting, but no uncontrolled action as a result. So, maybe Mr. O'Dette was speaking with a bit of hyperbole on that point (having said his hand would move a distance of "about a foot" on each stroke were his little finger not planted).
It should be said that the technique used in these videos is thumb out, rather than the thumb under as demonstrated by Paul O'Dette. Thumb out was used in the Renaissance, by vihuelists, and by lutenists as a development late in the period. But this does not necessarily negate planting the little finger, so you may find something worthwhile in it. The technique in the videos is obviously heavily informed by modern classical guitar study, not scholarly replication of late Renaissance approach, and there are consequences to sound production (primarily from use of nails) to which some would object.
However, it's worth noting that the techniques used on lute are not as monolithically codified as one might think, neither now, nor were they back in the Renaissance. There was, and is, individual variance. Though there are general prevalences, this can include such aspects as to whether or not to play with nails, whether the thumb is in or out, and, in regard to your question, whether one plants the little finger, and if so, to what extent. From what I can tell, Paul O'Dette seems fairly consistent in this regard, but I have seen other players who seem more free with it- they're more apt to move it around from spot to spot, or even lift it entirely for certain passages. Then there are mavericks who don't plant at all. So, it all depends on what you become used to doing, as justified in achieving the results you are after.