I now have had the opportunity to measure coverage of three different Computar lenses, 210mm, 240mm and 300mm. All give coverage of close to 95 degrees. Specific coverage in mm is as follows. The measurements were made on the ground glass of my 7X17 and 12X20 cameras with the lenses focused at 50 feet and could be off by a few mm.
210mm Computar, 456mm
240mm Computar, 523mm
300mm Computar, 655mm
Though not tested the 270mm Computar should cover about 590mm.
By contrast I have never seen or heard of a Kowa Graphic lens that will cover much more than 80 degrees. From this I must conclude that these are not the same lenses at all, or if they are the glass of the Kowas is installed in such as way that results in mechanical vignetting. I have never had an opportunity to examine a Kyvytar so I can not say how they compare to the Computar.
To figure out which Computar you would need for a specific ULF format note the following coverage requirements below. This is for the actual image of the negative, slightly smaller th an the theoretical diagonal of these formats.
So, we find that the 210mm Computar covers 11X14 with just a tad to spare and just misses the corners on 7X17 by a few mm. The 240mm Computar covers 7X17 with movement, and the 300mm Computar covers 12X20 with almost three inches of movement. and in theory the 270mm Computar should cover 8X20 with movements and just hit the corners oin 12X20.
I offer this information in an effort to clear up some of the confusion about Computar/Kowa/Kyvytar lenses and in the hope that more ULF workers will discover and use these wonderful lenses. In many ways they are truly unique and provide coverage for the size that simply is not available in any other design, regardless of price. They share some characteristics with Dagors but the circle of illumination of the Computar is not only about 10 degrees larger than the Dagor, but performance at the edge of the field is much superior.
Now I have got to go find a 270mm Computar!! And if anyone has specific design information about these lenses I would be very appreciative if you would provide me with the source.