Hey there Capn, no cropping/cutting of the picture. With a constant height design the height stays constant, the width just changes. The screen you use is a 2.35 ratio. When you watch smaller aspect ratios all you do is mask the sides with curtains just like the movie theaters. I'll try to explain better.
As you know with a 16:9 screen, if your watching 2.35 movies you still have black bars on the top and bottom, actually those black bars account for 33% of the total picture that is lost, so your not making use of all your resolution. They have to do this so the entire 2.35 movie fits within the 16:9(1.78) ratio screen.
Anyway, in my case my screen is 51" x 120" wide for 2.35. When I watch movies in lower AR's the Prismasonic lens has a "pass through" mode so the image passes through the lens and appears on the screen just as if I didn't have an anamorphic lens.
Now when watching 2.35 material, first you have to have a scaler to vertically stretch the material to fit the height of the screen to make use of the full panels. Your only adjusting vertically, not horizontally so it makes the image tall and skinny. This is where the lens come to play, you then use the stretch knobs to horizontally stretch the image to fit the 2.35 screen and the picture looks normal again.
As far as the scaler goes, many people use HTPC's, or other high priced scalers. Some DVD players and some projectors will perform the needed initial stretch.
Anyway, if you go to AVSforum every, there is a great new board for 2.35 users, it is starting to become very popular. I tell you, now that I can experience all the wider movies as they were intended to be viewed, I don't know how I ever stood for the black bars.
ISCO is another anamorphic lens, but more expensive than the above. Panamorph just makes vertical anamorphic lens's, meaning they take the previously stretched (scaled) image, and vertically compress it to achieve the 2.35 screen, end result the screen is smaller, unless you have a long throw projector. Prismasonic makes both vertical and horizontal lens's. My Prismasonic horizontally stretches the scaled image, so you can achieve a larger screen from any given throw distance.