Bell & Howell Trionar projector lens adapter

thingiverse

This is a projector lens adapter, currently featuring a Nikon F-Mount connector but slated for potential upgrade to a Sony E-mount connector in the future. It enables the utilization of older Bell & Howell 4" Trionar Anastigmat ƒ/3.5 projector lenses on digital cameras by simply screwing the lens into the adapter and adjusting focus with a twist. This often produces remarkably flat backgrounds, but when point highlights are precisely managed, it creates dramatic soap bubble bokeh. By default, the 4" Trionar is configured as a macro lens for Nikon devices, limiting focusing to close-up shots only. To achieve infinity focus, the last inch (25mm) of the bakelite lens housing must be carefully cut away, allowing the lens to screw deeper into the adapter and focus at infinity with Nikon cameras. The package includes an optional lens hood that can also accommodate a 52mm filter.