Add magnification to Lightbox Plus?

I have Lightbox Plus installed and working well on my site.

I’m wondering now if there’s any way to add a second layer of enlarging, so that if people click on the lightbox image of a painting, which is exactly fitted to 100% of the screensize, that they could then see a super-closeup magnified image. This way, they’d be able to see the brushstrokes and so on, before ordering a print of the painting.

Is this what secondary lightboxes are supposed to do? I haven’t had any luck so far with secondary lightbox settings.

Thanks for any help with this.