Production - how to make a transparent text box

Through looking at past double page spreads, often the text boxes were transparent in order to still see the main image, as well as read the text.
I wanted to know how to do this and see what my double page spread would look like with this effect. In order to do so, I needed to research it.
The answer straight away came up on google.



I then tried it on my text box.
Below is the text box with 100% capacity.

  

Below is the text box with 80% capacity.

  

I quite liked this effect as it not only followed codes and conventions of a double page spread, but it also showed more creativity by still being able to see the main image.