The Pentacon Six System
by TRA

The Kilfitt Zoomar Sport-Reflectar 500mm f/5.6
mirror lens for the Pentacon Six
 


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This lens was apparently designed by the American Zoomar company but manufactured in the Kilfitt factory in Munich in what was then West Germany.  The lens name ring bears the words “ZOOMAR MUENCHEN SPORT-REFLECTAR 1:5.6 500mm Nr. [and the serial number]”.  “MUENCHEN” is a way of transcribing the German name for Munich, München, when the u-umlaut (“ü”) is not available on the keyboard (or in former times, with telegrams, for instance).

1:5.6 is a popular German way of specifying a maximum aperture of f/5.6.  The disk in front of the centrally-placed rear-facing mirror has the Zoomar logo, which contains the words “Kilfitt” and “ZOOMAR”.  The lens is also engraved “Lens made in West Germany” on the back surface.

The lens cap says “Zoomar West Germany”.
 
Focussing

There is no other lettering on the lens: no indication of focussing distance and no focussing index mark.  In consequence of this, there is of course also no depth-of-field scale.

There are two focussing knobs on this lens, both slightly under the lens and near the back, for easy operation with the left or the right hand.  An unusual feature with this lens is that the focussing is internal.  Rotate one of the focussing knobs while looking through the viewfinder and the image will come into sharp focus, but the external body of the lens does not increase or decrease in length.  (The rear mirror is moved within the lens housing.)

With this particular example of this lens, there is no option to fit a focussing lever.  However, some later versions of the lens were produced with such a lever, which is in any case removable and often appears to have been lost by a previous user.

Tripod sockets

The underside of this lens has two tripod sockets, for ¼ “ and for 3/8”.  It may be possible to use this lens on a bean bag or other suitable support (for instance, a cushion on open a car window).  However, for most use it is best placed on a tripod – as indeed would be the case with any lens of this focal length.

The tripod sockets are mounted directly onto the lens, not onto a tripod collar, so it is not possible to rotate the mount round the lens.  On uneven ground, a level setting must be obtained by adjusting the length of one or more of the tripod legs.



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The left-hand focussing knob can be seen in this image (arrowed)

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The two tripod sockets (and the other focussing wheel)
can be seen in this image.


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A user’s-eye view of the lens mounted onto the Pentacon Six

Lens shade or hood

This lens has a deep integrated lens shade that is simply pushed forward to shield the lens from unwanted stray light from outside of the image area.  This will in most cases improve contrast and reduce flare considerably, so it should be used.  Because of the integrated design, there is no chance of leaving it at home or losing it, two fates that often befall lens shades.

This lens hood can be seen in the fully forward position in all the above pictures.
 
Aperture values

As is well-known, it is not normally possible for mirror lenses to have a variable aperture.  In practice, this means that the only way of controlling the exposure (apart from by selecting film of a suitable speed or sensitivity) is to change the shutter speed.

However, this Zoomar lens has perfected a concept that was not new, the use of filters at the back of the lens.  But  whereas the Carl Zeiss Jena Spiegelobjektiv has one neutral density filter and then a range of different coloured filters, the designers of this lens realised that most people preferred to shoot in colour, so there are no coloured filters (which would of course normally only be used with black and white film).

Instead, this lens has three neutral density filters of different densities and one plain glass filter.  These four filters are mounted on a large wheel or disk, the edge of which protrudes above the top of the lens.  Corresponding to each filter there is a marking on the edge of the disk.

However, instead of reading “ND×2”, “ND×4”, etc, f/stop values are marked.  This is not strictly-speaking technically accurate, as the aperture is not changed.  Therefore rotating this wheel cannot increase (or decrease) the depth of field in the resultant image.  However, using these numbers may be easier for some users to understand, taking away the need to make exposure calculations.
 

The four numbers are corresponding to
f/5.6 the clear glass filter
f/8 ND×2
f/11 ND×4
f/16 ND×8


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Here the “f/11” setting (ND×4 filter) has been chosen.
I could have digitally made the “11” in this image whiter, but that is how it is.





For the picture on the right, I removed the filter wheel from the lens.  (This is not something that I recommend that you do, as it involves partially dis-assembling the lens!)  Here you can see the four filters.  Because of the shadows cast by the ND filters onto the background paper in this picture, it is not possible to appreciate exactly the different densities, but I can assure you that each of the filters is different and results in exposure equivalent to the f/-stop values given on the edge of the wheel.


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The filter wheel clicks into position for each of the filters.  However, here I have deliberately partly rotated the wheel, to leave the filters in an intermediate position, so that it is possible to see how they are mounted.
 


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Because of the use of f/ numbers to indicate the effect of each filter, the user reading off combinations of shutter speeds and apertures from a hand-held meter will easily know which shutter speed to set, depending on the “aperture” (i.e. the filter) selected.  Naturally, those using a metering prism, as here, merely need to centre the needle in the viewfinder as normal, in this case by doing the following:
1) choose a filter 
2) rotate the meter dial (in stop-down mode) until the needle is at the meter index mark
3) check the shutter speed that is nearest to the index mark on the metering prism and set that speed on the camera.
If a suitable speed is not offered, change the filter (or select “f/5.6”, which puts the clear glass filter in the light path) and repeat steps 2) and 3).
 
Case

The lens is supplied in a smart aluminium case.

However, some 40-50+ years after manufacture, the foam lining of the case has disintegrated, as can be seen from this photograph.


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This has also been observed with another example of this lens case, so is clearly not unique.

Nevertheless, it is possible to obtain suitable foam, which these days is usually supplied in a light grey colour.



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The foam in the lid, which has an undulating surface, is called “convoluted foam” and it can be found on the web both in the UK and in the USA (and no doubt in other countries, too).  Suppliers will cut the foam to size, which is what I had done here.  However, note that with convoluted foam the minimum thickness from the supplier that I found is 40mm, which is a little more than I would have preferred for the lid.

Size and Weight


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To give a better idea of the size of this Zoomar lens, it is here pictured alongside the Arsenal 3M-3B 600mm f/8 mirror lens.
Inevitably, the f/5.6 Zoomar lens is of necessity larger than the f/8 Arsenal lens.
Here it is shown with its lens hood retracted.

Key data
 
 

Lens 500mm Sport-Reflectar 600mm Arsenal 3M-3B 500mm Pentacon 500mm Arsat APO
Maximum aperture f/5.6 f/8 f/5.6 f/5.6
Minimum aperture  –   –  f/22 f/45
Filter size 118.5 mm 1 Front: M 98 × 1
Rear: M 52 × 0.75
118 × 1 95 × 1
Weight with front cap 2655g 2200g 3500g 1650g
Rotatable tripod plate collar No Yes Yes Yes
Tripod socket size ¼" and 3/8" ¼" and 3/8" 3/8" 3/8" (to be checked)

Note

1 There is, however, no thread for mounting filters to the front of the lens.  The rear filters are approximately 35.8mm in diameter.  However, they are not designed to be replaced and anyone seeking to do so would need to disassemble the lens.
_____

The weight of this lens compares extremely favourably with other 500mm lenses.  The larger maximum aperture of the Zoomar lens results in a lens that is heavier than the Arsenal mirror lens.  Both of these mirror lenses are approximately 1 kg heavier than the 500mm Arsat, but 1 kg lighter than the 500mm Pentacon lens.

Its minimum length when mounted on the Pentacon Six is approx 180mm, which is extremely short for a 500mm lens.
Its maximum length (with the lens shade fully extended but no lens cap in place) is approx 238mm.
Largest diameter: approx 136.3 mm
To this must be added the size of the tripod-mounting plate or platform.

Date of manufacture & current condition

I would suspect that the Zoomar was last produced at the end of the 1970s.  The Pentacon 500mm lens was produced from the late 1950s until about 1990, and the Arsat was produced in the mid 1990s.  Several small batches of the 3M-3B were produced between the mid 1970s and probably about 1990.


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Many decades after manufacture, and having been stored by a previous owner in an unknown environment, the surface finish of this Zoomar lens is now slightly mottled.  However, this is not particularly obvious even when the front surface of the lens is carefully studied, and it appears to have no effect on the quality of images produced by the lens.

Lens mount

Like other Kilfitt and Zoomar lenses, this lens was available for a range of Medium Format cameras with focal plane shutters.  For use on the Praktisix/Pentacon Six it requires the “WESI” mount on a WESI base.  The WESI base is held in place with four screws, and both the base and the mount can be changed if required, in order to mount the lens on other cameras – always assuming that you can find the appropriate mount or can get one made.

In due course I hope to be able to add a review of the quality of the images produced with this lens.
TRA
12.5.12.

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© TRA First published: May 2012  Revised: July 2015