I've done some legwork on this lens, and here's what I know.
This is a Zeiss Luminar lens. It is made for macro work, and quite sought after, especially in a shutter. It is easily adaptable for medium format use as well.
The Luminars, long out of production, came in four lengths: 16mm, 25mm, 40mm, and 63mm. Useing bellows, they would give from 2x to 50x enlargements. They look like microscope objectives with an apperture.
They have plenty of coverage for 4x5, but at extreme enlargement, depth of field can be razor thin. Hey, its a Zeiss lens, razor thin depth of field, and razor sharp image.
I have been shocked to find the prices of this lens. I have seen sold prices for it of $750 without the shutter, and for sale prices over $1000, also w/o shutter. Last week on eBay a 40mm and a 16mm sold for $360 and $505 respectively.
I am a photographer that loves having fine equipment, but the deal I got on this lens and camera combo, is too god not to resell. I will be selling the lens in a few weeks to help pay off my new Deardorff. I've already got an MP4 set up with the Tominon set of lenses (135, 105, 75, 50, 35) to do my macro work.
I'll put up some pictures of the lens, and a shot or two with it sometime soon. Something this nice, I just got to play with it a little.