make product image larger?

im overriding the template of the product page, but having trouble figure out how to replace the main product image to use the larger file?

i see in the code, '<img src="<?php echo $this->item->thumb_image; ?>"'
so, I replace with, '<img src="<?php echo $this->item->popup_image; ?>"'

but it doesn't change anything? i already made the span 6 to handle the larger image area..
not sure what's the best way to show a larger product image?

rcm.cbwebdev.com/index.php/critical-infr...mat-tanker-trailer-2

Hi again,

You should also go to EShop -> System -> Configuration -> Image tab, at Thumbnail image size, change the size of image there too and test again.

Sincerely, Giang