Sensorex

TTL progression from the Automex models in 1967

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Miranda took the logical step of moving the CdS meter inside the camera to make a TTL model, which became a mainstay of their product range for years. Because of the removeable prism, the meter could not be positioned to read through the pentaprism block in the standard manner of many other cameras. Miranda chose to provide tiny slits in the mirror and mount the cell directly behind instead.  All Miranda viewfinders work with the TTL metering in the Sensorex and other models, too.

Sensorex - first version with f1.9 lens Sensorex - last version "C" with f1.8 lens

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sensx_back_lq.jpg (64356 bytes)The new model continued the large, non-rotating shutter dial mounted over the rapid wind lever. All the meter coupling features from the Automex III were retained, giving match needle TTL metering at full aperture. At this time, this was an upmarket feature, only the Minolta SRT101 and Nikkormat providing similar functionality in the price range.

Naturally the other Automex features were retained. Interchangeable viewfinders (but not screens), the same dual lens mount, and quiet mirror and shutter. The body is the same size as the Automex cameras. Sensorex retained the decorative plate in front of the viewfinders, a legacy from the original Automex, and all viewfinders from the Automex models will fit on this camera.

Minor features included a microprism rangefinder, self timer, film wound indicator, and self-zeroing film counter. Lenses for the Sensorex  included a spring loaded lever for manual diaphragm operation to preview depth of field.  There was still no shutter speed or aperture indication in the viewfinder, only the two meter needles for matching exposure.

Viewfinders for the Sensorex were the same as for the preceding Automex models. They had to be deeper in mount depth compared to the earlier series Mirandas. At the front of the prism, the camera sported the meter plate, and the Automex/Sensorex viewfinders were built accordingly. They are not interchangeable with the earlier Mirandas or the F/G/Fv/Sensomat series.

Production Variations
Sensorex was produced between 1967 and 1972, and we can identify seven almost-the-same but distinct variants.

Type First Serial No.
we have seen
Standard
Lens(es)
Meter
Type
Max Apert.
1.9 or 1.8
Meter
Needle
Back
Hinge
Finish
1 705xxx 50/1.9 spot 1.9 open "C" removable chrome
2 717xxx 50/1.9 spot 1.9 closed circle removable chrome
3 770xxx 50/1.8,50/1.4 average 1.8 closed circle removable chrome
4 900xxx 50/1.8,50/1.4 average 1.8 closed circle removable chrome
5 900xxx 50/1.8,50/1.4 average 1.8 closed circle removable black
6 929xxx 50/1.8,50/1.4 average 1.8 closed circle fixed chrome
7 929xxx 50/1.8,50/1.4 average 1.8 closed circle fixed black

Parts identification from the Sensorex   manual

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Miranda Sensorex Lenses
Many, many lenses here :-)
17/4
21/3.8
28/2.8
35/2.8
50/1.9
50/1.8
50/1.4

105/2.8
135/3.5
135/2.8
180/3.5
200/3.5
300/5.5
400/6.3
90-230/4.5
55/3.5 macron

Note: Sensorex Lens page is still under construction - there is a large number of lenses to document.

Other Lenses:
All MIRANDA Automex and Sensorex lenses will work  with full diaphragm automation and coupled metering.

All other MIRANDA or SOLIGOR lenses with internal diaphragm control, can be used with transfer-value  metering.

See notes below on metering system operation with different lenses.

Miranda first introduced their new f1.4 lens with the second version of Sensorex.sensx_ib_3_lq.jpg (62292 bytes)

Standard Lenses
Left to Right:
50/1.9, 46mm filter, standard aperture scale
50/1.8, 46mm filter, standard aperture scale
50/1.4, 46mm filter, first type, cutout aperture scale
50/1.4, 52mm filter, standard aperture scale
  (found on Sensorex C and later Sensorex II)

sensx_50s_lq.jpg (43087 bytes)

Viewfinders
VF-1     Waist level viewfinder with flip up magnifier
VF-3     Combination critical focus viewfinder,with 15x magnification in one position, and 5x magnification in flipped up position.
VF-4     Magnifying waist level finder used mostly for scientific or astronomy work. Introduced later in the Sensorex series; the original version of the VF4 was only available for the Laborec and model G.

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Lens Adaptors and other Accessories
By the time of the Sensorex, Miranda offered a comprehensive range of adaptors for both other SLR lenses and to be able to used Leica or Contax lenses for close up applications.

Focabell bellows, microscope adaptors, flash brackets were some of the other items from a comprehensive range.

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Metering
Miranda had one engineering compromise to make with the introduction of a TTL metering model. With an external meter, there was no need to accomodate the maximum aperture of the lens, but this is necessary for a TTL meter. In other makes offering the meter coupling as a first with TTL, it is simple to offset the connecting lever individually for each lens to provide the right connection position. However, Miranda already had lenses out with the aperture connection arm in a uniform, fixed position, so it was not possible to make this change without causing obsolescence and and probably a lot of user confusion. So, Miranda engineers provided an adjustment to let the user "dial in" the maximum aperture of each lens as it was mounted on the camera. It's another step, later this would seem clumsy, but a good compromise at the time. As a benefit, since the control adjustment was managed within the camera not the lens, the engineers could also provide a linear aperture reading scale for the coupling lever on the body. Thus, any lens could have its maximum aperture set and the TTL reading adjusted at full aperture using the needles in the viewfinder, and the correct aperture value read off the body. This again can be cumbersome, but it is in practice second nature once you get used to the system. Look at the pages alongside from the IB to understand how the Sensorex metering system works.

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User Notes and what to look for:

Sensorexes were generally tough, well made, and without particular weaknesses. A very large number were made (no, we don't know just how many) and you can find a near-mint working example quite readily on the www.ebay.com web site. For practical user purposes, the differences between the variations does not matter.

The original Automexes are about 30 years old by now, so the metering system is a probably weak spot. It uses the older mercury 625 battery, which is no longer available in the USA at least. I have heard positive results from using the 625A  cell and adjusting the ASA to compensate for increased voltage, but be careful, the higher voltage could possibly cause cell damage.  There are a couple of gotchas to look for in the metering system. Firstly, the battery compartment may well need cleaning and the contacts polished, especially if an old cell has been left inside. Within the top left housing, the battery compartment only contacts the meter circuitry by spring pressure, and this may fail after a long time. It is easy to repair. The ASA and maximum aperture variable resistors can get dirty with intermittent results, and the OFF/ON switch in particular suffers from this. Finally, the cell under the meter can fail, or worse, the wires leading to it via the moving mirror break internally. Either of these conditions is usually not repairable or not economic to fix.

As with the Automexes, the wind lever is quite highly geared, and the lever short, so the wind can become quite stiff as the lubricants dry out. The shutter too can get sluggish and taper on the top speeds, or hang on the slower speeds. Test it by opening the back, taking off the lens, and pointing the camera at a white wall or sky. Release the shutter at each speed. You should see the complete film gate evenly exposed at each speed. Top speeds may show part of the film gate blacked out if they are not operating properly. Flash synch speed is 1/60 second, use 1/30 if you are not sure of the shutter accuracy.

Chrome finish on the Sensorex varies depending on the model variant. The original Sensorex inherited the less-than-satisfactory soft finish from the Automex III, and is often found in lacklustre condition or worse. Finish improved with each model, so the last version (the Sensorex-C of 1971) sports the same strong and high gloss surfaces found in a good example of the Sensorex II or Sensorex EE. If you only want one Sensorex for your collection, the later ones are the best to search for. 

Lenses for the Sensorex are very common, probably the most common of all Miranda lenses. Look for Miranda lenses with the aperture setting ring coupling arm. Again, a culling through eBay will show that the most prolific is the 135mm, then the 35mm, and it is not hard either to find 28mm, 105mm, or 200mm.  For the detailed collector, there were several model series produced that more or less matched the Sensorex changes, but in practice the lenses all look virtually the same and certainly function in the same manner. The only zoom produced was a 90-230mm f4.5, based on the Soligor T4 lens of the time, but with a fixed Miranda mount. It isn't marvellously quick to use. More exotic lenses were offered as time went on, from 17mm at the wide end to 400/6.3 telephoto.

At the same time as the Sensorex, Miranda offered the Fv, G, Sensomat and Sensomat RE models. These provided either no metering or stopdown metering, so that the aperture setting ring did not have the coupling arm. Otherwise, the lenses were virtually identical in most cases. Be careful when purchasing lenses without confirming that the coupling arm is present. The plain lenses can be used on Sensorex, but it is much more fiddly and involves transferring aperture settings from meter scale to the lens itself.

All the Soligor and Vivitar T4 lenses will also work with a Miranda Sensorex mount - but beware, the actual T4 mount has a common weakness, the aperture lever mount tends to come loose and loose its rigidity. Buy carefully.