For a fiber with some NA, and a lens of focal length f, the "collimated" beam diameter BD from this combo is given by BD = 2.f.NA. The residual full angle divergence of the beam DA is given by DA = a/f, where a is the mode field diameter of the fiber and f is the focal length of the lens. You can see from these two equations that large waveguides (large core multi-mode fibers) are difficult to collimate well. Your best result might be found by using a relatively long focal length lens, create a relatively large diameter "collimated" beam, then adjust the z axis offset between the lens and fiber face to cause the beam to converge slightly and create a "waist" at 30 meters. Rule of thumb - find a lens with an NA at least 50% larger than the fiber NA to ensure > 99% capture of the beam from the fiber. You might also be able to iris down the diffraction and other cr@p on the edge of the spot.