There are the following callback-functions:
onbeforeopen
called before opening the lightbox
if callback returns false, lightbox will stay closed
onafteropen
called after lightbox is opened and transition is finished
onbeforeclose
called before closing the lightbox
if callback returns false, lightbox will stay open
onafterclose
called after lightbox is closed and transition is finished
onfullscreen
called when fullscreen-mode gets activated
onfullscreenoff
called when fullscreen-mode gets deactivated
onslideloading
called when content of a slide starts loading
second argument is the slide
onslideloaded
called when content of a slide is loaded and appended to the lightbox
second argument is the slide
onslideopen
called when a slide gets visible to the user
second argument is the slide
onslideclose
called when a slide gets not visible to the user
second argument is the slide
onslidezoom
callback when the slide gets zoomed in
second argument is the slide
onslidezoomoff
callback when the slide gets back to normal
second argument is the slide
onmodal
callback when the user interacted with a modal
second argument is the modal-data
onfilter
callback when content is added to a slide
second argument is an object with the content that gets added, content can be adjusted

The first argument of the callback-function will always be the lightbox-object.

You can add the callbacks on initialization:

$('.bblb').bbLightbox({
	onbeforeopen: function() {
		console.log('beforeopen');
	}, onafteropen: function() {
		console.log('afteropen');
	}, onbeforeclose: function() {
		console.log('beforeclose');
	}, onafterclose: function() {
		console.log('afterclose');
	}, onfullscreen: function() {
		console.log('fullscreen');
	}, onfullscreenoff: function() {
		console.log('fullscreenoff');
	}, onslideloading: function(lb, $slide) {
		console.log('slideloading', 'slide ' + ($slide.index() + 1));
	}, onslideloaded: function(lb, $slide) {
		console.log('slideloaded', 'slide ' + ($slide.index() + 1));
	}, onslideopen: function(lb, $slide) {
		console.log('slideopen', 'slide ' + ($slide.index() + 1));
	}, onslideclose: function(lb, $slide) {
		console.log('slideclose', 'slide ' + ($slide.index() + 1));
	}, onslidezoom: function(lb, $slide) {
		console.log('zoom', 'slide ' + ($slide.index() + 1));
	}, onslidezoomoff: function(lb, $slide) {
		console.log('zoomoff', 'slide ' + ($slide.index() + 1));
	}
});