Hi guys.

I recently purchased a second hand De Vere 504 with an Ilford 500h head. It's the first enlarger I've personally owned, but I've used this combination before at university.
In the university darkrooms we had technicians to take care of most of the equipment, so it wasn't required of me to know many of these things. I've been reading and found out that not all enlarger lenses are made the same (discrimination!).
In the equipment I have there are three lenses - 50, 80, and 90mm. I'm wondering whether the 90mm would be usable to print 5x4 film. If not, what sort of lens would you recommend?

Thanks,
Rado.