spider 50% het albino x normal = 50% chance at spider 25% het and 50% chance at just 25% het albino.. but if you prove out the spider to be het albino then the hets you produce will be 50% instead of 25%
spider 50% het albino x albino.. well that is a little trickier since you don't KNOW if your spider is het. Basically this is a good way to prove out whether your spider was het for albino also or not.
If it was het for albino, then you would get 50% chance at a spider albino and 50% chance at a spider 100% het albino.
If you don't get any albinos in the clutch, there is a decent chance that the spider is just a spider and not het for albino, in which case you have 50% chance at spiders and 50% chance at normals.
hope this helped.