Medium Format Lenses with the Pentacon Six Mount
A comparative test
by TRA

1000mm


Carl Zeiss Jena made a 1000mm mirror lens with the astoundingly fast aperture of f/5.6.  But this comes at a price, weight-wise: 14 kilograms. However, even at this weight, it is still 2½ kilos less than the Carl Zeiss Oberkochen f/5.6 / 1000mm Mirotar lens that was briefly available (to special order!) for the Hasselblad, and was subsequently supplied for various Rollei and Contax SLRs (according to Richard Nordin in his book “Hasselblad System Compendium”).  The CZ Jena mirror lens is supplied in a sturdy wooden case, bringing the total transportable weight to over 20 kilos (equivalent to your check-in luggage allowance with many airlines!).  Until recently, none of my tripods has been up to the job of reliably supporting this lens without me standing nervously nearby, ready to offer extra support.  I still feel that it is likely to have very little practical use for the average amateur – though it is superb for wildlife or for some sports photography.  (To read a report on a suitable tripod for this lens, click here.)


[Spiegellr: This image from the front of a Pentacon catalogue published in 1975 shows the 1000mm mirror lens, which dwarfs the 35mm cameras in the picture.
The three tall lenses at the back on the right are (from left to right): the 180mm Sonnar (with lens hood), the 500mm Pentacon (with lens hood) and the 300mm Sonnar (minus lens hood).  There was a subsequent version of both of the Sonnars, each slimmer than those shown in this photograph.]

Before looking at this lens in detail, let us look at an alternative way of achieving 1000mm with the Pentacon Six.

500mm × 2

It is possible to add a 2× converter to the 500mm f/5.6 Pentacon lens, yielding a 1000mm f/11 effect. All converters with Pentacon Six mount available to me fit this lens. By adding the Joseph Schneider converter to it and mounting the combination on an Exakta 66 with a TTL head, one obtains full (open) aperture TTL metering with this lens! (but one has to remember to swing the ring to stop down to the chosen aperture before firing!)


[C308-15 A real “long tom”: the Pentacon 500mm lens plus the Schneider 2× converter]

This close-up of the Schneider 2× converter shows how the converter transmits information to the metering prism on the Exakta 66.
Before mounting the converter on the camera, rotate the converter’s front ring A, on which you can see the aperture values 4 and 4.5 in this picture, to bring the maximum aperture of the lens you plan to use in line with the index mark (the white diamond behind it).  (There is also a setting for lenses with a maximum aperture of f/5.6.)
This moves pin B to depress the appropriate maximum aperture switch in the metering prism when the converter is mounted on the camera.
To find the right working aperture for the shutter speed chosen, rotate rear ring C on the converter until the meter indicates correct exposure.
This moves cam D to tell the meter which aperture has been selected.
Then set this aperture on the lens itself.

If you are using a non-Schneider lens, as is the case with the 500mm Pentacon, remember to stop down the lens, if it has a pre-set (i.e., non-automatic) diaphragm.

To go back to the section on teleconverters, click here.

What a remarkable degree of magnification this combination yields!  With a sturdy tripod and fast film, you can really bring distant details in close-up (if you don’t get arrested first!).  At f/5.6, I used the Panagor 2× converter, which we now know I should not have done.  A large part of the image is extremely soft.  At f/11 I tried both the Panagor and the Schneider 2× converters.  The Panagor/Pentacon combination delivered a remarkably sharp image showing great detail over most of the frame.  As expected, the Schneider/Pentacon combination produced a yet sharper image.


[C301-10: Pentacon 500mm at f/11 + Panagor 2× converter: Exakta 66 with 400ASA film.  Shutter speed 1/125]


[C302-16: Pentacon 500mm at f/11 + Schneider 2× converter: Pentacon Six with 160ASA film.  Shutter speed 1/30]
(Colour differences between these two shots are due to the prints that came from the lab, not the lenses.  As I have scanned from the prints, not the negatives, I have not been able to correct this in my imaging software.)

So, to achieve 1000mm, should one use the 500mm Pentacon with a 2× converter, or the 1000mm Carl Zeiss Mirror Lens?

Here is how they compare for size – in these two pictures with the Joseph Schneider 2× converter for the Exakta 66 fitted to the Pentacon lens.

[C374-34]

[C374-35]
1000mm

Now let’s look at the mirror lens in greater detail.
 

[C369-8/9]
A maximum aperture of f/5.6 is exceptional for a 1000mm lens, and it makes possible using the camera’s top shutter speed of 1/1000 sec, which is really essential on many occasions with such a great degree of magnification.

In fact, with 400ASA/ISO (27DIN) film, you may find that you have too much light!  A neutral density filter is needed.  Fortunately, the lens comes with a range of filters built in, but here the design shows its age: most of them are for use with Black & White film: 
Filter                Exposure increase factor
Dark yellow                       2
Orange                            2.5
Light red                          10
Dark Red                         16 (!)
Also usable with colour film are two other filters:
Filter                Exposure increase factor
UV                            1 (i.e., no exposure increase required)
ND 25% absorbtion  1.5 (i.e., about half a stop)
This is really not adequate; one really needs at least an ND filter with an exposure increase factor of 2 (1 stop), preferably two different ND filters, one giving the effect of an f/8 maximum aperture, the other the effect of an f/11.


[C374-36an]
The filters are inside the lens, so it is not possible to swap them for something else without partially dis-assembling the lens!  This should not be difficult for an experienced camera repair person, but it is not something that I am prepared to undertake.

Each filter has a diameter of 57mm, so it should be possible to obtain alternative ND filters at modest cost.  The filters used are 5.23mm thick – thicker than most filters used these days, but I doubt that a slight difference in thickness would result in any optical or mechanical problems.

The ingenious could no doubt find a way of inserting a filter within the focussing bellows, though removing it would be impossible without taking the lens off the camera.

One of the fitted filters is always required – normally the UV filter.  To select a different filter lift the small lever visible under the left-hand knob, labelled “A” in the image here, and then rotate the large knob anti-clockwise.  There is some resistance, but one by one the filters swing into place.  The order in which they are mounted is: UV, ND, Yellow, Orange, Light Red, Dark Red.

The knob to the right of the focussing bellows (“B” in the image here) is the focus control.  As you can see from the images below, it is the lens that is mounted on the tripod, so the focussing bellows only have to support the weight of the camera.

The magnification with this lens is so enormous that you may have difficulty working out just where it is pointed at, as you search in the camera’s viewfinder for your subject!  To help you with this, there is a sighting mark on the top of the lens, labelled “C” in this image.

Compatibility problems

It is not possible to mount this lens on the Exakta 66 with its TTL metering prism, as this extends too far forward of the front of the camera body.  However, it will, of course, mount on the Pentacon Six with its metering prism, or on the Exakta 66 with the non-metering prism or other viewfinder.

It is also reported that it is not possible to mount this lens on the Kiev 88CM.  The round flat plate or ring of metal just forward of the lens mount is fouled by the front of the Kiev 88 camera, which was never designed for Pentacon Six lenses.  The standard flange distance of the Kiev 88 – the distance between the film plane and the front surface of the lens mount on the camera – is 82.10mm, the same as the Hasselblad 1600F on which it was based.  The flange distance of the Pentacon Six is 74.10mm.  Therefore, when the Kiev 88 was modified as the Kiev 88CM (perhaps standing, in Cyrillic lettering, for “Six Mount”), the lens mount had to be recessed below the front of the camera.  However, it is of course not possible to slice off 8mm from the front of the camera.

It may be possible to overcome this problem by placing the shortest of the Pentacon extension tubes, the 10mm tube, between the back of the 1000mm lens and the Kiev 88CM.  However, it would be necessary to check if infinity focus is still possible with this tube in place and the lens focussing bellows compressed to the maximum.    Information on this tube can be found here.  As I no longer have a Kiev 88 camera with the Pentacon Six mount, I am unable to check this myself, and would welcome feedback from someone with this lens and the Kiev 88CM.
___________________

To give an idea of the scale of this lens, here are some shots of it mounted on the Pentacon Six (or perhaps we should say that it is the camera that is mounted on the lens, and not the other way round!)

[C369-1]                                                               [C369-7]                                                           [C369-4]
(Is the camera behind the lens in the first shot?  I’m not sure!)

So much for the lens itself.  Now how about the quality of the images it delivers?
 

[C369-17:] Here is a shot taken with the 80mm Biometar standard lens at f/11. 
The first thing that I discovered when the film came back from processing was that the shutter on this particular Pentacon Six had developed serious banding at 1/1000sec.  This is visible as darker vertical bands of exposure about one third of the way in to the image from the left.
[C369-162]
In this shot taken from the same position a few minutes earlier we can see the degree of magnification achieved with the 1000mm lens.
The banding caused by the shutter problem is clearly visible.
We can also see slight cut-off at the bottom of the frame, and a very small area of vignetting in the top corners – though this is quite marked.
I have here scanned the whole of the negative.  In practice, the very edges would be masked in a slide mount or in the negative holder in an enlarger, so that these areas of vignetting are unlikely to be visible.
An ND4 filter would have yielded a better-exposed negative.

[C369-16midcrop]
To examine further the quality of the images produced by this lens, here I have enlarged a tiny area of the centre of the image.
[C369-16edgecrop]
And here I have enlarged an area of similar size at the extreme right-hand edge.
Both of these enlargements show the outstanding quality of the images produced with the 1000mm mirror lens: there is no chromatic aberration (colour fringeing) and no linear distortion (curving of straight lines).  Image contrast and sharpness are excellent.  The only limiting factor is the film, as at this degree of enlargement we can begin to see the grain (Fuji NPH 400).  In these bright winter conditions, a slower film would have been more suitable – in fact, on this occasion a 100ASA/ISO (21 DIN) film would have been correctly exposed.

My conclusion is that most people will not need the Carl Zeiss Jena 1000mm mirror lens, but if you do need it, it will give you outstanding results.

P.S.  After a service, the camera produced correctly-exposed images with no signs of banding at 1/1000sec, as it had previously done.

Why isn’t the lens barrel black?

For most of the past 30 years or so, it has been customary to produce camera lenses with a black finish, although “chrome” finishes seem to be making a comeback.  However, the Carl Zeiss Jena 1000mm mirror lens is most often seen in a light grey that is just off-white, and there are also some that are finished in an extremely light green that is also only just off-white.  Some late-production examples were produced in black, but this is much rarer.

Why did Carl Zeiss choose these extremely light colours?

In an article entitled “Line and Length” in the 19 February 2005 issue of “Amateur Photographer”, Geoffrey Crawley wrote this:
 

“There is a case for a white or cream finish for long lenses.  A few can usually be seen at sports events.  The idea is that sunlight is reflected and the absorption and consequent heating given by a black finish prevented.  Long lenses are susceptible to significant expansion and contraction in temperature extremes.”

To read a report on a sturdier tripod for 1000mm lenses, click here.

To go on to the next section, click below.
Next section (further 1000mm-1200mm tests)

To go back to the beginning of the lens tests, click below and then choose the focal length that you want to read about.
Back to beginning of lens tests

Home

© TRA January 2002, January 2013