----- Original Message ----- From: "J. C. O'Connell"
Subject: RE: M42 ultra-wide
I think the APS sized lens makes sense for one thing, the widest lenses, under 20mm. The reason is they would be much smaller and less expensive than ones designed to cover full frame 35mm and theretically they could also be sharper and more contrasty because far fewer elements would be needed to cover the APS angle vs, the full frame angle of the same focal length.
You might want to rethink that, based on products that are on the shelves.
The DA 14mm f/2.8 offers APS sized coverage in a lens with 12 elements in 11 groups.
It takes a 77mm filter is 3.3 inches in diameter, 2.7 inches long, and weighs 14.8 oz.
This lens has approximately the same angle of view as a 20mm lens has on 35mm.
The FA 20mm f/2.8 has 10 elements in 9 groups, uses a 67mm filter is 1.73 inches long, 2.75 inches in diameter and weighs in at 9 oz.
The APS coverage lens is substantially larger and heavier, and has more glass than it's equivalent lens coverage in full frame 35mm.
I realize this is one example only.
William Robb
