Shooting "barebow" (no sights, stabilizers, clickers or other artificial gadgets) makes accuracy and consistency harder to achieve, particularly in field archery when one has to adjust to different distances and footing.
But there are methods more natural than modern mechanisms to help the archer adjust to divers distances, such as the gap method (having a gap or distance between the spot and the tip of the arrow for a given distance), string walking (adjusting the position of the hand on the string according to the distance) and face walking (altering one's anchor point depending on the length of the shot). Depending on the category of field archery one is taking part in and the relevant rules and prohibitions, some archers use markings on their bow or string as indicators of aim and elevation according to the distance of the target. However, in some categories, such indicators are forbidden.
Enter the old manuscript, Arab Archery, and a method of working out a point of aim that would no more disqualify a traditional archer for cheating than the gap, string walking and face walking methods. It suggests using the knuckles or fingers of the bow arm as indicators:
[Look] at the target with the left eye in relation to the knuckles of the left hand. In the case of a short range the archer should look at the target from above the third knuckle of the index finger of his left hand. If the arrow then falls short because of the lightness of the bow or the heaviness of the arrow or the weakness of the archer himself, he should raise the third knuckle of his index finger into alignment with the target- If the range be long and the bow strong, he should aim at the target in the same manner as prescribed for the short range. If the arrow then falls short because of its weight or because of the weakness of the archer or because of the long range, he should align the third knuckle of his index finger with the target- If the arrow should again fall short, he should raise his left hand a little and look at the target from between the two knuckles at the base of the index finger and middle finger. If the arrow once more falls short, he should raise his left hand a little more and look at the target from the point bisecting the knuckle at the base of his middle finger. If the arrow should again fall short, let him look at the target from between the two knuckles at the base of his middle finger and ring finger- If the arrow should still fall short, he should raise his left hand a little more and look at the target from between the two knuckles at the base of the ring finger and the little finger. If the arrow should even yet fall short, he should raise his left hand further and look at the target from his forearm. If the arrow should exceed the mark, he should bring his left hand downward little by little, just as we have described in the case of raising it.
It has also been said that the archer may fix his aim by means of the fingers of his left hand by pointing the arrowhead at the center of the target. If the arrow should then fall short, he should raise his hand and align the index finger with the top of the target. If the arrow should again fall short, he should align the middle finger with the top of the target. If the arrow should still fall short, he should align the ring finger with the top of the target. If the arrow should again fall short, let him align the little finger with the top of the target. Finally, if the arrow should even yet fall short, he should align his forearm with the top of the target. If the arrow should exceed the mark, he must bring his left hand downward little by little, just as we have described in the case of raising it.
While I have yet to put this method to the test, it appears to be just as sound as the other natural methods of adjusting one's aim. And the beauty of this one - particularly the knuckle version - is that most people will not even know you are using any method at all!