Buhl 2 inch f2.8 Flat Field Ultrawide for Carousel format_APS-C 5 is a M42 mount

5 is a M42 mount prime lens

The Sony Cyber-Shot DSC-HX99 is a pocketable point-and-shoot camera with an improbable 28x zoom lens: this camera is barely over 3

8 lenses with 49mm filter threads

and socket moves smoothly

focusing and diaphragm work well

Buhl 2 inch f2.8 Flat Field Ultrawide for Carousel format_APS-C 5 is a M42 mountThis is a Buhl Optical Co. 2. 0 inch f2. 8 Flat Field Ultrawide lens for Kodak Carousel slide projectors, great for close range projection: 2 inches is about 50mm, and the default Carousel lenses tend to be around 102mm, so that's a fair bit wider. Light internal dust, very light haze, otherwise nice.