Miranda Viewfinder Screens

Miranda's special viewfinder system is wonderful in application of special viewing options, and it is also straightforward and accessible to repair.  It is actually a well sealed unit, but over a long period, the elements may become dusty or tarnished, and the viewfinder loses contrast and brightness. Every now and then I find a particularly grungy camera, or one with a stained or damaged screen, which simply begs to be repaired. Please read at least "MOST IMPORTANT ASSEMBLY NOTE" at the bottom of this page.

The diagrams below relate to models with built-in match needle metering. For earlier models, the system is a little simpler, and cruder using separate brass shim pieces instead of pre-fabricated exact shim frames. I've described this briefly for the FV model here.

If you don't need to dismantle the whole system, then I would recommend not doing so. Very often the top condensor lens is grimy or cracked, and that's as far as you need to go. The screen can be dusted off with compressed air in situ. The screen position within the camera is fixed, centering of the viewed image is done with adjustments to the mirror itself. 

The diagrams and instructions below are from the disassembly of a Sensorex II, serial number 8322088. With the prism removed, there is a row of components from top to bottom visible down to the focus screen. It is possible to remove and replace all the viewfinder components without having to remove any of the meter parts. All meter models have a similar construction, with the components necessary to accomodate the match needle metering. The meter coil in all instances is situated under the left hand top plate, and the meter needle and follower arm protrude through the side of the finder recess to appear above the focussing screen. 

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Start by selecting the correct screwdriver (straight or phillips head, depending on the model) and gently unscrew the six screws holding down the top plate (1). Do this evenly, since the plate will be lightly spring loaded and tends to jump off. The next component is the condensor lens (2) which can be carefully lifted up.  (For non-metered models, generally the condensor lens faces convex upwards, for metered models, the convex side faces downwards. Take particular care to establish which way your camera is set up BEFORE taking this top lens out.) Next, remove the plate spring (3) then the black plate with meter needle index (4) is next. This can be carefully extracted towards the right hand side away from the meter needles.
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The main screen (5) is next, and it can be tricky. The meter needles sit just above this screen. You must avoid getting serious fingerprints or tool marks on either surface. The focus screen itself is on the underside, and finely engraved fresnel rings on the top side.

I found the easiest method is to gently push up on the right hand side from underneath, inside the mirror chamber. Use a soft q-tip, or carefully padded tweezers. Once the right hand edge is above the top of the finder edge, you can carefully extract it sideways while avoiding the meter needles above it.

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The last components are straightforward to extract around the meter needles. Watch carefully for the sequence and orientation, since (6) and (7) are exact thickness shim components. They may be tapered, although I'm not sure on this point. Part (8) is a black flocked mount and little skirt acting as a light trap around the edge of the finder base.
sensxII_vf_15_lq.jpg (51519 bytes) sensxII_vf_12_lq.jpg (22529 bytes) sensxII_vf_4_lq.jpg (48477 bytes) Now you can clearly see the meter needles in this fully disassembled view.
By now, you should have a row of identifiable parts lined up in sequence similar to the row below:
sensxII_vf_1_lq.jpg (59633 bytes)

Cleaning, basically. The condensor lens is fairly soft optical glass, and it tends to accumulate grime. Any good lens cleaner and micron lens cleaning cloth will work.

The screen is different. Don't use any solvent or cleaner, unless you have specific knowledge about this! If the screen is only dusty, I recommend compressed air (from a can) or an incredibly gentle brush. For stained screens,  I have been successful  with warm water with soft liquid soap, very gentle finger washing. Rinse with clean water and allow to dry naturally.

As a radical non-collector sidetrack, installing another newer type of screen may be feasible. I tried the Minolta Acute Matte for size, and it looked very promising, although I hadn't time to completely test it.The new split image rangefinder and enhanced generation screen showed significant improvement  in the viewfinder.

Mostly the reverse procedure of the above, paying particular attention to keeping the screen (5) fingerprint and dust free, carefully putting the other parts in sequence around the meter needles up to the final condensor lens (2) and the cover plate (1).

The condensor lens (2) is fragile. It has significant tapering towards the corners, which makes it very likely to crack as the top cover plate (1) is tightened. It is also prone to being out of position slightly and having one of those flat corners caught incorrectly on the top edge of the well in the body, or with the spring underneath. I suggest the following procedure:

(a) put condensor lens (2) in place, centered as close as possible. It will be sitting uniformly on the flat spring (3) underneath.
(b) place the cover plate (1) carefully in position. Insert the six screws and just start to thread each one.
(c) gently and uniformly tighten the screws, pushing the screen against the flat spring, to perhaps 1/3 tight. You will feel the screws start to resist the tightening more suddenly. Stop at this point with all 6 screws.
(d) use a sticky finger on the condensor lens (2) to ensure that it is evenly centered under the cover plate, and when it is pressed down, that all corners fit smoothly down into the viewfinder well in the body and do not catch on the edges. You can feel that the flat spring under it is providing a uniform pressure. If the central position is not perfect, or the flat spring slips position (either of which unfortunately,  is quite easy to have happen) then the condensor is at risk if you tighten further. In the correct position you can feel the lens pressed uniformly against the plate spring and dropping into the body. Incorrect, you can feel it catch on the edge at one side.
(e) now, gradually and uniformly, tighten down the 6 screws with the cover, checking the uniformity of pressure against the condensor lens each time around. You can also hold the condensor lens down deliberately in the correct position, but, be careful not to push too far and push the lens against the meter needles. A fine balance is needed here.
(f) clean fingerprints off the top of the condensor lens on completion.

Here's all the components laid out again, in order:

..and best wishes to anyone brave enough to tackle their Miranda.
Unfortunately, finding spare condensor lenses is getting more
difficult, except by cannabalizing other cameras. Of course, we
would love to know of a source for these parts!

I would also appreciate feedback, comments, additional information
or variations found, to add this page.

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