High speed water droplets photography

int sensorPin = A0;    // select the input pin for the fototransistor
int resistorPin = A1; // select the input for the potentiometer

byte relay = 3;
byte led1 = 4;
byte led2 = 5;
byte led3 = 6;
byte led4 = 7;
byte led5 = 8;
byte led6 = 9;
byte led7 = 10;
byte led8 = 11;
byte led9 = 12;
byte led10 = 13;
char ledbar[10] {led1, led2, led3, led4, led5, led6, led7, led8, led9, led10};
int sensorValue = 0;  // variable to store the value coming from the sensor
int resistValue = 0;  // Variable from the potmeter
unsigned long currentMillis;
long interval = 1000;
long previousMillis = 0;
//------------------------------------------------------------
void setup() {
  for (int z = 0; z < 10; z = z + 1) {
    pinMode(ledbar[z], OUTPUT);
  }
  pinMode(relay, OUTPUT);
  pinMode(sensorPin, INPUT);
  pinMode(resistorPin, INPUT);
  Serial.begin(9600);

}
//----------------------------------------------------------------
void ledson(byte x) {

  for (int z = 0; z < x; z = z + 1) {
    digitalWrite(ledbar[z], HIGH);
  }
}
//------------------------------------------------------------------
void ledbar1() {

  resistValue = analogRead(resistorPin);
  resistValue = map(resistValue, 0, 1023, 0, 400);

  AlleLedsUit ();
  if (resistValue > 0 & resistValue <= 40)
  {
    ledson(1);
  }
  else if (resistValue > 40  & resistValue <= 80)
  {
    ledson(2);
  }
  else if (resistValue > 80  & resistValue <= 120)
  {
    ledson(3);
  }
  else if (resistValue > 120  & resistValue <= 160)
  {
    ledson(4);
  }
  else if (resistValue > 160  & resistValue <= 200)
  {
    ledson(5);
  }
  else if (resistValue > 200  & resistValue <= 240)
  {
    ledson(6);
  }
  else if (resistValue > 240  & resistValue <= 280)
  {
    ledson(7);
  }
  else if (resistValue > 280  & resistValue <= 320)
  {
    ledson(8);
  }
  else if (resistValue > 320  & resistValue <= 360)
  {
    ledson(9);
  }
  else if (resistValue > 360  )
  {
    ledson(10);
  }
  //Serial.println(resistValue);

}
//------------------------------------------------------------------
void loop() {
  // read the value from the sensor:
  sensorValue = analogRead(sensorPin);
  sensorValue = map(sensorValue, 0, 1023, 0, 1000);
  //Serial.println(sensorValue);
  if (sensorValue < 500)
  {
    delay(resistValue);   // delay instellen voor de waterdruppel
    digitalWrite(relay, HIGH);
    delay(750);    // delay voor het relais
    digitalWrite(relay, LOW);
  }
  //============ een keer per seconde potmeter uitlezen ===========================
  currentMillis = millis();
  if (currentMillis - previousMillis > interval)
  {
    previousMillis = currentMillis;

    ledbar1();

  }
}
//----------------------------------------------------
void AlleLedsUit () {// all leds off
  for (int z = 0; z < 10; z = z + 1) {
    digitalWrite(ledbar[z], LOW);
  }

}