Q:

How to enlarge shadow radius for a view

I have a ImageView that I want to add a shadow to it, but with a large radius area.! 
I tried using elevation but it doesn't seem to increase the radius very much..!  
I also tired using xml drawable shape but with no luck. 
 Here's an example of what I want to achieve.  assuming the white circle is the image. 

A:

I tried using elevation but it doesn't seem to increase the radius very much..! 
I think the ImageView doesn't implement the elevation attribute, you can just write attribute because ImageView is a subclass from View class. 
If you need to implement that elevation and got the shadow, do it with FloatingActionButton instead or if you don't need to use FloatingActionButton and keep going with ImageView you have to set a CardView as a container for ImageView and add the elevation to CardView. 