I know it shows the 35mm field of view of the lens, but since you are zooming in to cutout the surround, at the point that you just fill the frame of a camera does it equal the same field of view of a 35mm film(motion) camera, or is it slightly cropped in further giving a slight zoom over the standard.

Meaning if I place the lens on a 35mm film (motion) camera and shoot a scene, and place an adapter on a digital with extreme and the lens tip is in the same place is the field of view the same or cropped?

And does this change if you switch on the same adapter lens the camera used from say an XHA1 with 72mm lens to a hf10 with a 37mm lens filter?

It seems on my older non extreme I am magnified a bit much and switching from the large camera to small changes the field of view by maybe 30% which is dramatic, I can go from using a 50mm to needing a 35mm for the same shots from the same location. This is a very old design and a spinner so I have to cut in a bit deeper to pass the center but I am curious now of the letus since that is what I am planing to get soon.

I've been asking similar questions. Here's a response from Philip Bloom: "The Letus can actually subtract a little on the focal length. It actually depends on what camera you use and how much you zoom into the ground glass."

http://www.hostingphpbb.com/forum/viewtopic.php?t=24&postdays=0&postorder=asc&start=45&mforum=philipbloom

Hi Stephen,

I've made a framing card for the letus which might be of help.
You can download it from:
http://www.adeszo.nl/letus/LEX-GG-framingcard.png
Just print on an A4 sheet of paper, and use it to determine the proper amount of zooming in on your groundglass to get matching lens angles with 35 mm cine or 35 mm still.

Hope this helps.

Regards,
Robbert-Jan

that is great! thank you, I will check it out.