IMS/B4-Mount Optical Viewfinder for SI2K.

[Bob Hart]

P+S Technik designed and manufactured an optical viewfinder which incorporated an optical split taken from within the space between the B4 flange and the IMS flange on their B4 mount which corrected lenses for three chip cameras to single sensor cameras.

It was a beautiful piece of work, engineered with all the precision one has become accustomed to from P+S Technik. It was very expensive and at the time was unaffordable for me.

The company offered a limited number on their German eBay site and I luckily bought one at a heavily discounted price.

For those owner-operators still with the SI2K, Ikonoskop A-CAM owner-operators who have the IMS-Mount version and RED owners who defied the threat of loss of warranty and fitted the IMS mount to their REDs, the optical viewfinder may be found to be a useful accessory. For RED owner operators, this is suited only for 1920x1080 or 2K cropped sensor work.

The camera system information is not reproduced in the viewfinder. As a focusing tool on the fly, it will be hard to beat and one traditional film operators are familiar with.

With the eyepiece in the level position and the lens zoom position matched, the natural direct left eye view and the right eye view through the finder become comfortably harmonised without eye strain, which speaks for the precision of the design and build work by P+S Technik.

[Bob Hart]

A short heads-up for people with SI2K Mini's, full camera-recorders with IMS Mount or those RED owners who have fitted the P+S Technik IMS Mount system to their RED ONE cameras and may want to shoot in 2K with cropped sensor and may like to have optical viewing through the taking lens.

P+S Technik have relisted their B4 Mount / optical viewfinder for the IMS mount system at a heavily discounted price here :-

P+S TECHNIK SI-2K Optical Viewfinder for B4-Mount Lenses / Optischer Sucher | eBay


It is uniquely designed for a 2/3" or Super16mm sized sensor camera, the SI2K. The unit entirely substitutes for the IMS B4-Mount. A B4-Mount lens fits up to the front of it.

As far as I am aware, there has only been a limited production run on the viewfinders which are apparently based on the Evolution finder for ARRI motion picture cameras. We here in Western Australia have taken two for SI2Ks as an optical 3D pair so there may not be many left in stock.

The viewfinder/B4-Mount optically corrects 3 x sensor designed lenses for single sensors.

[Bob Hart]

Here's a link to some happy snaps of the viewfinder-mount.

A QUICK LOOK AT P+S TECHNIK SI2K OPTICAL VIEWFINDER - CORRECTING B4-MOUNT - YouTube

[Bob Hart]

This image might prompt your curiosity factor.


Two P+S Technik SI2K B4-Mounts with optical viewfinders as binocular finders on a camera pair.

The viewfinders harmonise nicely, due to precision of P+S build quality. This would be fine with a parallel rig.

To deal with convergence pulling, the upper articulating eyepieces would have to be fixed together with the friction screws backed off and may still disharmonise as the swingarms will move rearwards and the eyepiece interaxial may shift unless the swingarm friction can be reduced.

[Bob Hart]

Here's a clip of Ricey getting all ecstatic over optical 3D pre-visualisation.

P+S TECHNIK IMS B4-MOUNT OPTICAL VIEWFINDER 3D PAIR - YouTube