I've got a simple photographic site and it uses large image sizes throughout.
On the archive page, however, I've got about 35 posts each showing the first image of each. By default, the images being uploaded are around 600 pixels wide. However, on the archive page they need only be 150 pixels wide.
The problem: I don't need 600 pixel wide images on this heavily populated archive page.
I understand WordPress generates smaller images when they are uploaded to the media gallery. Is there a way I can use a smaller image that has been generated instead of the large, default image?