I have been trying to work this out for the last couple of weeks, but I just keep getting the Newtonian deviation in angle for a path of a photon travelling from x=-∞ to x=∞. At first I tried putting the actual path into a computer simulation, transforming back and forth between the hovering observer's frame locally with the photon and that of a distant observer, then again using the coordinate radial and tangent accelerations that the distant observer measures for the photon. My last attempts were to simply find the change in angle mathematically, where asin(vy / v) ≈ vy / v for a small change in angle with small M and large point of closest approach R (= y), per dx = v dt for a photon that otherwise travels a straight line path along x with an instantaneous coordinate speed v according to the distant observer, then integrating that along x to find the total change in angle. Locally I am applying the equivalence principle, using the relativistic acceleration formulas to find the change in radial speed for a freefaller initially falling at the same coordinate speed vr1 as the photon, radially only with no tangent speed. Since that freefaller is inertial and falling at the same radial speed as the photon, from the freefaller's point of view, then, the photon just travels directly away tangentially at c, and as the freefaller continues to travel inertially, this should continue to be true. So whatever final coordinate radial speed vr2 is achieved by the freefaller over time dt, this will also be achieved by the photon in the radial direction. The tangent speed according to the hovering observer, then, since the freefaller and hovering observer both measure the total speed c of the photon, is just vt2 = sqrt(c^2 - vr2^2). The change in speed vy is then found from the radial and tangent changes in speed, giving the change in angle along y according to the distant observer, then integrated for the entire path of the photon along x to find the total change in angle. But this hasn't been working out so far, giving only the Newtonian change in angle instead of twice that value which GR predicts. Could someone please show me how to derive the GR value using the equivalence principle in this way? Or if it is usually found in some different way, that would be fine too so that I can compare the difference to what I am attempting. I only understand algebra and basic calculus, though, so please present your derivations that way. I also want to see it visually, worked out according to what each observer actually measures, bit by bit over small portions of space, then integrated to find the whole, so no quicky math or matrix solutions please. Thanks.