Once you start cutting you do not need to focus on the bubble being in the middle. The bubble is just a starting reference point. Once you have the CreaClip in position, you just need to hold it steady in that approximate position. While cutting, if you happen to move your hand out of position and the bubble moves out of the middle, that's ok. Keep cutting just as long as you are about 80% in its approximate position and you will get great results. Remember you can always stop and start over if you lose position.