Shopify Buy button product image higher quality

Site URL: https://guimauve.nl

Hi guys,

I've embedded Shopify into SP and I am almost there. I've changed a lot of stuff, improved the quality of the image of the pop up greatly, added zoom on hover etc. However, and this is where I am still frustrated: I want my grid photo to have the same quality as the pop up photo (which I've changed to 2048px in the .js file) Can someone help me out. Is this even possible? 

Also, I would like to add opacity to the image's on my product page. Does anyone know a simple code for that?