[Max Vondel (Peter)]

I have a question relating to 35mm film size (36x24mm) and DSLR sensor size(24x16mm). The cmos sensor is smaller than the traditional film size.
And I have read online that a 75mm SLR lens is equivalent to a 50mm DSLR lens. So for example my old Pentax 50mm F1.4 will be equivalent to a 33.3mm lens on my DSLR body. Could anyone confirm that this is correct?
Secondly, what would be my F-stop for my 50mm if used at say full F1.4 be in equivalent 33.3mm.? And is there a simple way to calculate this.
Many thanks in advance