I have a Triplet with a 150mm Fuji lens, and I immediately gave up on the supplied optical viewfinder and use the Artist's Viewfinder app on an older iPhone. The wide lens on the phone is just wide enough to equate to the 150mm lens. I just hold the phone camera directly above the camera lens to get a rough idea of the framing - it isn't going to be exact. I'm waiting for a simple phone holder from one of the Chinese vendors which will hold a phone at 90 degrees to a standard hot shoe (i.e. with no swivel joint in between) to keep the phone somewhat aligned.With very wide panoramic lenses, the phone camera can't cover the whole width of the view, but if the top and bottom are in view, you can use a bit of imagination. I don't expect my framing to be down to the last tenth of a degree anyway. However, for a 75mm lens, you might want one of the latest phones with an ultra-wide third lens - I can't comment on those - or experiment with a cheap ultra-wide add-on lens that clips over your phone lens. The viewfinder app can account for one of those if you know its magnification.