How to make a plane blur objects behind it?

I decided to switch from a perspective camera to an orthographic camera in my mobile sidescroller game. It looks more retro and will allow me to do somethings that would have looked awkward with a perspective camera.

The issue is that the depth of field included in the standard assets doesn’t work with an orthographic setup. I have mountains in the background that I want slightly blurred.

I’m wondering if I could write a shader that I could use for a plane that I would simply place in front of the mountain, and have it blur everything behind it slightly.

The problem is, I have trouble understanding shaders and while I’m still learning Unity/game development in general, I’ve read up on shaders and I understand the concept but when it comes to actually writing them…I’m at a loss

If someone can give me some pointers on how to write a shader to do this, I’d greatly appreciate it.

Unless there is a better approach that I could use to accomplish this?

@alexshultz
Hi there!
I found this one: Unity Asset Store - The Best Assets for Game Making
I don’t know if it works tho, I’m testing it right now.

EDIT: Yepp, it works. You can even stack the planes bahind eachother to achive higher quality blurs.