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Alternative Imaging Methods
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Old October 18th, 2008, 02:41 AM   #1
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Join Date: Dec 2003
Location: PERTH. W.A. AUSTRALIA.
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I have been very lazy

I have been in the throes of writing a how-to on initial assembly of Mini35-400 and Letus Extreme systems, in the case of the Letus Extreme, the complete adaptor and rods bundle.

With other things demanding attention I have put it aside for the time being.

For assistance of those mounting up the Sony PMW-EX1, here is an extract. There are no diagrams or illustrations. The measurements quoted should not be regarded as applicable to all other appliances as manufacting variances and the real possibility of my own errors could be misleading.

As I have previously stated, my comments and suggestions should be tested by experimentation and not simply followed.

The dimensions published have not been checked across more than one sample of either product so do not account for variations.

Also, the adjustment positions have been arrived at by modifying a Letus Extreme for lateral centricity adjustment. The centricity was then matched to an individual new EX1 camera with optical steadyshot switched off, the adaptor squarely mounted and not subject to any bending forces.

The rods system was then assembled around the pre-assembled EX1-Letus Extrreme combination and adjusted until the frame was again correctly centred, then the dimensions measured off.



LETUS EXTREME/SONY PMW-EX1 RODS SYSTEM.


INITIAL ASSEMBLY INFORMATION

POSITIONAL ADJUSTMENTS PRIOR TO MOUNTING CAMERA AND LETUS EXTREME TOGETHER.


The vertical positional adjustments can be higher or lower provided the relationship between the pillar positions remains the same. ( As in - add or subtract the same preferred height adjustment to all pillars. ) As a personal preference, I allowed a "tail" of the support pillars to hang down below the bridgepieces to enable easier measurement, but also to prompt myself to avoid the tempation of standing the entire assembly on the floor at risk of falling or being kicked over onto its side.

I find it helpful to fasten the Letus body support pillar and its bridgepiece to the Letus body with the thumbscrew before assembling the camera to the rods system. I chose to position the bridgepieces so that the clamping screws are underneath, not on the upper surface.


LETUS BODY FRONT PILLAR SUPPORT AND BRIDGEPIECE.


Distance between lower edge of sliding support pillar to lower surface of bridgepiece - adjust to 6.7mm to 7.00mm and lock off.


CAMERA SUPPORT WEDGEPLATE REAR PILLAR SUPPORTS AND BRIDGEPIECES.

Distance between lower edge of sliding support pillars to lower surface of bridgpiece - adjust to 10.3mm to 10.5mm and lock off.


COMPLETE RODS, BRIDGEPIECES AND SUPPORTS ASSEMBLY.

THE FOLLOWING REQUIRES THE LETUS BODY FRONT SUPPORT PILLAR TO HAVE BEEN MOUNTED FORWARD OF ITS BRIDGPIECE, IN CORRECT POSITION FOR ASSEMBLY TO THE LETUS BODY, WHICH IS CUPPED OVERHANG FACING FORWARD AND THE FOREMOST OF THE SUPPORT PILLAR PAIR UNDER THE CAMERA WEDGE PLATE TO HAVE BEEN MOUNTED FORWARD OF ITS BRIDGEPIECE.

Distance between front face of foremost camera wedgeplate support pillar and rear face of Letus body support pillar - adjust to 197mm to 197.3mm and lock off. This adjustment is not set in stone but was a personal choice only. The sliding wedgeplate arrangement permits a wide range of positions.


UPPER BLUE WEDGEPLATE TO SUPPORT PILLAR PAIR LATERAL ADJUSTMENT.

Distance from left face of blue wedgeplate to left side faces of support pillar pair - adjust to 20.3 to 20.5mm and lock off. Make sure the screws are all in side contact with the lower face of their slots before tightening otherwise tripod head levelling bubbles may not be harmonised to the Letus upper and lower frame edges as seen by the camera.


The adjustments will put you in the close ballpark of positions required to offer the rods and bridgeplate up to the pre-assembled Letus and camera combination. The finer adjustment should only be regarded as correct when the mount ring is able to be square-on when secured to the back of the Letus body.


SAFETY AND DAMAGE CONTROL DURING ASSEMBLY.

The camera and Letus Extreme either singly or in combination are heavy enough to cause injury if dropped on the foot or an ankle during the assembly operation.

It is prudent to wrap a couple of turns of gaffer tape around the protruding ends of each of the silver rods where they poke through the bridgepieces rearwards of the rearmost bridgepiece and forward of the Letus body support bridgepiece to prevent anything sliding off the rods or the rods themselves sliding out and dumping the camera or Letus body.

It may be found helpful to leave the clamping screw on the Letus body support bridgepiece and the wedgeplate clamping lever loosened to enable you to slide the combination along the rods and wedgeplate to facilitate alignment of the thumbscrew holes if you choose not to pre-assemble the Letus body support pillar to the Letus body first.


CENTRICITY.

Compared to the Sony HVR-Z1P, the centre of frame of the PMW-EX1 seems to be a little more rightwards and there may be variance introduced by the rest position of the optical stablilser prism system across individual cameras.

The Letus Extreme itself also appears to have a slight bias also to the right. In the marriage of both products, there might be normally aceptable variances across individual camera units and the Letus adaptors which could be additive or substractive when both are joined. In some extreme cases of additive combined variance, the available groundglass area may become unacceptably confined.

It may seem helpful for frame centering, to offset the camera to one side by adjusting the blue wedgeplate to create a skew of the EX mount ring to rear-of-Letus-body junction. This may introduce a softness on one side edge or the other due to the plane of the groundglass no longer being square-on to the camcorder view. A common misadventure is to then assume the groundglass itself is not square-on, to pull the front off and attempt to adjust it.

The edge softness then may seem to remain when the groundglass is presenting a sharp texture across the camcorder view because the groundglass then becomes misaligned relative to the focal plane of the lens on front. This then requires a skew adjustment of the front lens mount to correct by unequal adjustments of the three spacer screws in back of the mount ring.

A common temptation is to re-centre the groundglass image frame by bending the entire assembly prior to locking off all fasteners. This practice is not recommended because of the compliant nature of the plastic camcorder structure. Over time, a secondary creeping deformity of some internal casework components may occur and cause focus or zoom movements to bind and fail. Needless to say, camera warranties will become void if damage is traced back to such misuse.

Last edited by Bob Hart; October 18th, 2008 at 03:02 AM. Reason: error
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