Background Opacity without breaking content to divs

Question

I mean I have <section> tag and I have background-image: url(...) and I want to know how to change the opacity of background but without changing opacity of child tags.

This is my code:

section {
     background-size: cover;
     margin: 0px;
           background: red;
     padding: 10px 10px 10px 10px;
     background-repeat: no-repeat;
      background-position: center;
    }
    #study {
     background-image: url(2.jpg);
    }
    h1,h2 {
font-weight: 1000;
font-size: 60px;
text-align:center;
color: black;
letter-spacing: 5px;
z-index: 500;
user-select:none;
}
#study:hover {
opacity: 0.8
}

        <section id=study>
        <h2>Text</h2>
<h2>But text gets lighter too!</h2>
</section>

Answer 1

Use pseudo elements:

http://jsfiddle.net/2dauqf9o/6/

section {
  position: relative;
  text-align: center;
  padding: 120px 0;

  &:after {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: red;
    content: '';
    transition: all .15s ease-in-out;
  }
}

h2 {
  position: relative;
  z-index: 1;
}


// Hover
section:hover {

  &:after {
    opacity: .6;
  }
}