Drawing the bowstring
String drawing starts in the position where you ended after nocking. It ends in the position where bow hand is straightened and firm, and string hand releases the string.
Amount of draw
There is an ideal called full draw, when bow hand is totally straightened and string hand is positioned to the anchor point. The full draw will put most power to the shot. However, keep in mind that "full draw" is not as normalized as it would seem, because it depends on how long hands you have and where is your anchor point. Modern sport archer may consider as a full draw the string hand anchored in front of the eye, while for some historical archers the full draw ended somewhere behind the ear. The difference may be over 10cm, ant it will undubtely influence the power of shot. Such archer may then consider sport archers' anchoring at eye as only a partial draw, which would surprise many of contemporary archers. It would be more correct to deem as a full draw the draw length that the bow is constructed for (because it always is for some draw, nowadays usualy 28''), yet it does not consider the possibilities of archer. The conclusion is that even in "full draw" there is some (and not just small) variability.
You can also shoot with partial draw, when the string is released before the string hand gets to the anchor point. Because the string is usually released somewhere in the air, the point of release cannot be considered as an anchor point, the the release really happens somwhere "on the way". Sport archery does not respect partial draw at all, and marks it always as a mistake. The reasons are reasonable in many ways, but that does not mean that partial draw has no practical use.
Partial draw
- is weaker. With partial draw you can reasonably shoot only to a short distance, and you cannot count on that the arrow woulůd pierce, say, a plate armor.
- You must aim instinctively. The absence of anchor point brings some unpredictable bias to the shot, and even does not allow you to aim by looking along the arrow.
- is faster, from several reasons. The string hand does not have to go over such distance. What more, it must not hold such a strength, so you can hold the string by some more emergent way. And after the shot the string hand is not that far from the bow, so you can nock and shoot another arrow faster.
- The feeling is different. Full draw is really about "draw - release",, while partial draw is more a one-motion twang.
So a conclusion - partial draw enables to to shoot from a stronger bow as if it was weaker, and moreover faster. Practicaly it would be reasonable during emergency shot to a short distance, when you are in danger, but the enemy is as near that it is not problem to shoot him say in the face. In modern days (when you don't enter battles with bow so often) it can increase the speed of whole shot. It is useful if you fight for tenths of second.
The video shows first full and then partial draw.
Ways of drawing
In fact there are two ways to draw the string
1) By a string hand. First you straighten the bow hand and make it firm. Then you draw the string hand (holding the string) to the anchor point. Only the string hand moves when drawing. The bow hand may also bend in the shoulder (either in European way from bottom to the top, or in japanese way from the top to the bottom). Yet bow hand does not actively draw the string in any way, it just holds the bow against the pull.
This way of drawing enables you to add your back muscles to the drawing, which are stronger, so it is easier to draw the string with them. The stronger bow you have, the more important the back muscles are.
2) By both hands (double draw). The bow is at the begining in the position "in the middle", with both hands bent. When drawing, the string hand goes to the anchor point, while bow hand goes forward to a straightened and firm position. So the bow sort of "opens" to the both directions.
This way is a bit faster. It is generally your choice of how much of drawing you put on the string hand and how much on the bow hand. The more draw does the bow hand, the less you can use your back muscles. So the draw is faster, but weaker. It depends on your training and natural strength what the "weaker" means, and how strong bow you are able to draw in this way.
In reality both ways merge; in fact it could be said that there is just one technique (double draw), and it variates in how much amount of draw you assign to each hand. Yet it seemed reasonable to me to separate one "extreme" occasion with static bow hand, because it is what you are usually learned by modern archers, and what is important for drawing strong bows.
As for me, at leat partial draw by front hand helps me with instinctive aiming. You then have the feeling that you sort of send the arrow to the target. The information of eastern archers show that I am not the only one. These arechrs often end (after the shot) with the bow canted forward. Such position is achieved natuarlly by adding at least small draw by a bow hand in the time of releasing the arrow.
For more about different styles of string drawing see Styles of bowstring drawing