The reason I ask is because the mini35 GG has a area of 24x18mm. That's a 4:3 frame, which means if you use a 16:9 camera, it would either crop the top and bottom of the frame, or you would be left with two side black bars. How does it work with a native 16:9 camera like the XL2 or HD100 then?
In any case, I don't see how could you be getting the exact 50mm of a cine lens with the Mini35 when there's this frame aspect ratio difference, meaning it couldn't be the exact angle of view of the 35mm lens. What am I missing?

I don't know about XL2 but with Z1 works (same 16:9) You zoom in till you lose the edges.
Note: the GG is NOT 18/24 or any other format. The GG is ROUND, and so, you zoom in till you lose the "corners" of the frame, subject to the frame size on the camera (16:9 or 4:3)

A 28 or 32 Zeiss will give you the same perspective on an 18/24mm frame as an 50mm SLR (Canon, Nikon, etc) on a 24/36mm frame.

The GG in Mini35 does not cover 24/36mm frame (the circle is smaller) therefore, the image from a 50 SLR lens will be cropped to whatever could be framed zooming in to: 18/24 (for DVX100) or 16/26 (roughly) for Z1 (and other 16:9 native chips) equaling an 85 (roughly). In other words, when you use a 50 on Mini35, you get the same perspective as if you were to use an 85 on an SLR camera (or a Zeiss 50 as in motion picture)

Again, the Zeiss 50mm will show you the same image on film as well as on Mini35.
I hope this helps.

Thanks. But I'm still confused. So if you are zooming in a 18x24mm image(in case of a 35mm motion picture lens) with a 16:9 camera till you lose the edges, that means you are cropping the frame in the top and bottom?
Still the same perspective/angle of view of the 35mm motion picture lens, which has a 18x24mm frame?

I shot a film last year with the Mini35 and XL2. We shot in native 16x9 and the smallest lens we used was a 25mm and we never had a problem with seeing the edges.