Looking for Clarification on Photo Sizing Guidelines

[liddy21]

Hi there, 

I constantly run into issues putting banner images & product images on shopify because it get's all distorted. I am using the prestige theme currently, and on the right hand size it recommends a 1800x800px .jpg & 750 x 1100px for mobile. 

I made my banner with these dimensions on canva so I followed the directions with the correct image format. I always reference https://www.shopify.com/blog/image-sizes when uploading image files,  but I often find I have to go back and forth guessing and checking to see if the new image will fit proportionally. 

This hero banner on prestige theme isn't even remotely close. It is very very zoomed in. Does anyone have recommendations for approaching this? Am I doing something wrong? This would save me so much time in the future! 

Thank you in advance for your support.