The thing is, although both the organ and piano have the same keys (black and white, sometimes white and black), their action and sound production is inherently different.
On the piano it is quite natural to lift high the fingers and attack the keys with some force if you want to play louder, or with less force if you want the piano to sound softer.
All of this is unnecessary on the organ because the instrument does not react the same way the piano does. For instance, whether or not you play stronger or softer, the organ will sound the same.
This is not entirely true in some cases, but in order not to complicate things too much right from the beginning, let's stay with the most obvious feature - the dynamics on the organ is done differently from the piano.
So, how do you depress and release the keys on the organ correctly?
Well, it's quite simple. With one crisp and precise motion of the finger, press the key down and hold it until you have to release it. Do not make any unnecessary movements with the arm or had while holding the key depressed. Any circle motion that we do on the piano is not really needed on the organ.
Of course, we have to be always aware if there is any tension in the shoulders, or the arms, or the hand, the wrist etc. If there is, just try to relax it. Conscious deep breathing while playing helps to achieve that.
If you want to release the key, do not lift the finger from the key. Let it stay and rest on the keyboard.
Remember, the less movement you do on the organ, the more precise your playing will be. In this way you will be able to control and coordinate the releases much better.
So, the main thing to keep in mind here is:
KEEP THE FINGERS IN CONTACT WITH THE KEYS AT ALL TIMES.
If you come to the organ from the piano, it will be quite difficult to do it at first. You will have to think constantly about it. However, after some months of correct practice, you will form a good habit and never have to think about it again.
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