The Letus Extreme construction and optical path is wide enough to allow for a fixed non-adjustable relay of larger than 35mm motion picture frame sized image.

Some enthusiasts who want enhanced performance for new cameras like the Sony PMW-EX1 have sought an even wider groundglass view to grab that little more apparent resolution provided by scaling down the groundglass particle size relative to image size.

When pushing this envelope they have encountered a frame edge coming into the image before the other, which limits how much oversize image area can be scanned by the camera.

The Letus Ultimate has a lateral and vertical adjustment built in.



The Letus Extreme does not. Unlike the P+S Technik products which have an adjustable reflective element in the flip path, the Letus products now employ a composite prism assembly which is retained in a fixed position.

The mods shown in this clip enable lateral centering adjustment on the Extreme by adding three grubscrews to the case, two for adjustment/clamping, one for clamping only.

This adjustment is achieved by small angular movements of the entire composite prism assembly. One screw is backed off as the opposite screw is advanced until the prism image is in the required central position. Two strips of brass shim metal protect the sides of the prism from pressure chipping of the brittle optical glass by the ends of the grusbcrews.

The strips are retained to the ends of the casework by thin joints of contact cement.

In this clip, the two triangular shaped pieces of brass shim are represented by two triangles of blackened paper.


Two felt strips are added to work as rocker or pivot points to allow a slight movement of the composite prism in the adaptor. Another is added to the centre spine as a pivot point.

These two "rocker" strips are twice as high (two layers thick) than any other felt strips. They have to be otherwise the sides of the prism will bed down flat on all felt surfaces and not rock when the screws are adjusted.

Two more smaller felt strips are added where the corners of the smaller prism elements are likely to strike the casework in an impact.

The centre spine is covered with a thin wrap of transparent plastic to take up clearance, provide a sliding surface and protect the composite prism from scratches during adjustment.

In place of the synthetic rubber wedge retainer is a double tapered polypropylene strip, which a third screw bears against to firm the adjustment after it is made.



To permit the composite prism enough movement, approx. 0.9mm of extra space is created by shimming the front cover forward with two cardboard gaskets.

This is not a factory approved modification and will most definitely void any warranties. It should not be attempted by anyone without advanced handyman skills and home workshop equipment.