Thought I would add here the features of this lens.
The Mamiya Sekor 45mm f/2.8 D Lens is a moderately wide angle lens for the Mamiya 645 AF system cameras which has been totally redesigned to function brilliantly with Mamiya digital backs such as the ZD and others. It is precision manufactured in Mamiya's facilities in Japan.
As a lens designed from the ground up with the digital capture in mind, it has low-dispersion glass and floating lens elements to ensure edge-to-edge sharpness at any focusing distance without chromatic aberration. Wide angle lenses, due to the nearly-parallel angle at which light rays can hit the sensor at the edges of the field, have been known to cause color shifting with digital backs. But the Mamiya Sekor 45mm f/2.8 D lens directs its light rays so that they're all parallel when reaching the sensor, producing maximum sharpness and more importantly highest color accuracy.
The Mamiya Sekor AF 45mm f/2.8 D lens has a 16-bit CPU chip. This allows easy firmware upgrading, fine lens characteristic correction, and reliable communication between lens and camera body and digital back (when used with Mamiya 645 AFD II & 645 AFD III).
The lens' native angle of view is 76°, equivalent to a 28mm lens in conventional 35mm camera terms. The Sekor 45mm D's especially suited to architectural photography, where it will show off its ability to render perfectly-straight lines.
• Moderate wide angle lens for the 645 AF series cameras
• Equivalent to 28mm lens in 35mm camera terms, or a 32mm lens when used with the ZD digital back
• Ideally corrected for digital use, with parallel light rays and nearly nonexistent chromatic aberration
• Reaches a short focusing distance of 17.7"
• Made in Japan
You can read more here and yes new it is out of stock
http://www.bhphotovideo.com/c/product/634237-REG/Mamiya_210_616_Sekor_45mm_f_2_8_D.html
