After an intensive design and development process, True Lens Service (TLS) a company out of the UK, has developed a brand new housing that adds modern functionality to the much-loved Speed Panchros without losing that desirable “Cooke Look”. This process involves a number of significant upgrades, such as:
There is now imperceptible backlash in the focus movement, zero image shift and smooth transition of the optical unit within the lens housing.
Positive stops on the focus ring are designed to withstand the rigours of modern day drive systems that can often overrun the frail end stops from some earlier designed re-housings. The iris ring is also governed and designed to stop cleanly at either end of the scale.
Internally adjustable stops on the iris aperture ring mean that the lens can be set to overrun the end markings, if required, but this will not necessarily mean that the lens will open or close any more than the original specified settings.
The shimmable stainless steel PL retains the iris datum ring using eight cap head screws.
The variable pitch cam that guides the optical unit gives the focus puller an even spread of the focus scale around the circumference, which is particularly useful towards infinity.
The cam groove inside the focus barrel has been calculated and cut to give a constant acceleration of the optical unit along the barrel during its rotation. Machining the two part, sprung loaded cam follower that runs along the cam is an intricate operation which is critical to gain the correct ‘feel’ of the finished lens movement.
The same can be said for the machining of the cam groove with surface finish, produced to give a smooth movement of the optical unit within the housing. The entire focus movement is designed to give reliable, repeatable, progressive and constant performance throughout its working operation. The internally adjustable focus stop gives a clean, solid halt to the travel at either end of the scale. Once set, it must hold its position as it is matched to the cam groove and focus scale on the outside. Spring-loaded support bearings on the internal carrier help give the optical unit a smooth and cushioned ride along the inside the lens barrel.
The focus barrel is held on a specially designed bearing that eliminates shake and free play from the focus movement in the focus barrel. This is a key component to the whole re-housing.
Focus Gear & Iris Drive
Externally, the focus and iris drive rings both have 0.8 MOD drive gears that will be the same size and in the same position throughout the whole range of Speed Panchro re-housings.
The front diameter is 110mm and can accept standard matte box clamp rings and doughnut adaptors, without affecting the focus movement. The front diameter of the lens has been set at this dimension to ensure that no vignetting takes place in the corners of the Academy format, which the original Speed Panchros were designed to cover.
The front internal filter thread is M105 x 0.75 pitch to accept standard filter of that diameter. Deep internal reicing on the inside of the front carrier helps reduce internal reflections in difficult lighting situations.