Hey ricarubio,
For a period, Instagram allowed images beyond the standard sizes from their API of 150×150, 320×320 and 640×640. This is no longer possible I’m afraid.
You could set the width of your feed and number of columns to fit well with one of the avialable sizes from the API. For example, a 960 pixel wide feed with 3 columns would use the 320×320 sizes efficiently.
Hopefully that helps!
– Craig
