OK Rich -  sorry I'm just confused.

Quote from Sigma Imaging UK Web site: 

Use is not possible for digital single-lens reflex cameras with image elements larger than the APS-C equivalent size, 35 mm single-lens reflex cameras, and APS film single-lens reflex cameras. 

And every one said, 'If we only live,
We too will go to sea in a Sieve,---
To the hills of the Chankly Bore!'
Far and few, far and few, Are the lands where the Jumblies live;
Their heads are green, and their hands are blue, And they went to sea in a Sieve.

Edward Lear
http://www.nonsenselit.org/Lear/ns/jumblies.html