Scale on scroll: Javascript modifications

I have the following script for scalling an inside a div on scroll:

const zoomElement = document.querySelector(".zoom");
let zoom = 0.5;
const ZOOM_SPEED = 0.01;

document.addEventListener("wheel", function(e) {

if(e.deltaY > 0){
zoomElement.style.transform = `scale(${zoom -= ZOOM_SPEED})`;
}else{
zoomElement.style.transform = `scale(${zoom += ZOOM_SPEED})`; }

});

On full scroll the image scales to zero. I require the script to only scale from 100% and stop scaling at 50%.

Please state "I can help" in your reply if you can help.