  The classical 1966 theorem of Tverberg with its numerous variations was and
still is a motivating force behind many important developments in convex and
computational geometry as well as the testing ground for methods from
equivariant algebraic topology. In 2018, B\'ar\'any and Sober\'on presented a
new variation, the "Tverberg plus minus theorem." In this paper, we give a new
proof of the Tverberg plus minus theorem, by using a projective transformation.
The same tool allows us to derive plus minus analogues of all known affine
Tverberg type results. In particular, we prove a plus minus analogue of the
optimal colored Tverberg theorem.
