|What are the differences between an Ultraphot ll and a #lll?|
|The exposure control units of the # lll's photobodies are much more sensitive, employing a photomultiplier instead of a system based on a vacuum photocell. An important part of their camera circuitry is housed in the power unit drawer and therefore the cameras cannot be operated without it (except for the 'T' setting of the 5 X 4). On the other hand, # ll works at 'line' voltage and all the camera circuitry is contained in the microscope itself. Consequently, the # ll was often supplied without an integrated power unit - just transformers for the lamps.
In # ll, the tubehead, large format photohead and limb casting are (in almost every case*1) finished in black enamel, the base and body casing being in a 'hammered' metallic grey. # lll's are finished in two-tone grey, the lighter tone (on the casing and base) having an 'orange peel' texture.
The base of a # lll is much deeper than that of a # ll (130mm against 85), 50 mm wider (500mm), very widely chamfered and fitted with 2 retractable lifting bars*2 on each side. The right hand side is also fitted with a row of filter plungers. The sides of the base of a # ll are not chamfered and lack filter plungers and lifting bars.
* 1 An Ultraphot ll Met in two-tone grey livery is illustrated on p. 66 of Zeiss Information, Vol. 72 (1969).
* 2 The # lll figured on p. 97 of Optical Systems for the Microscope (W lll/71 Too) apparently lacks lifting bars, but this could have been a prototype or merely mutilated by the block maker.
|What are the differences between a # lll and a # lllB?|
|Exposure control in the large format photoheads of the Ultraphots ll and lll is based on a sensor situated just outside the picture area, on its lefthand side (see the rectangle engraved on the frame of the focusing screen). In the case of the lllB, however, metering is at a spot in the centre of the picture area: a much more rational and convenient arrangement.
Externally, the differences are hardly obvious. The focusing screen of the large format photohead of the # lllB has, at its centre, a clear circle, 7mm in diameter, to indicate the area over which light measurement occurs, but such screens are also sometimes found fitted to # lll's (or even # ll's) as replacements. The presence or absence of the engraved rectangle on the left side of the focusing screen frame provides a more reliable clue. If the 5 X 4 photohead of either be removed from the microscope, 2 (red) electrical connector blocks can be seen on its underside, the one on the left with 3 pins, that on the right with 24. In the middle is a single pin with white insulation in the # lll, while the lllB has 2. The actual body of the lllB has only a single distinguishing feature: a 15mm diameter metal plug on the lefthand side of the limb casting. It is painted to match the surrounding area and bears 2 small holes to allow it to be unscrewed.
|How did the external appearance of the Ultraphot ll change during its production life?|
|The instrument illustrated in the article which first described the newly developed Ultraphot ll (Zeiss Werkzeitshrift no.19, March 1956*3), was almost certainly a prototype, since it has the levers for securing the stage and substage brackets on the right hand side and the substage focusing knob on the left, a very temporary arrangement, apparently, as they are already shown reversed in 'Instruments for Doctors and Hospitals' published in the same year (Vlll/56). Nevertheless, photographs of this early variant were used to illustrate an Ultraphot brochure as late as 1958 (Scho.1X/58 Koo).
Even so, the early Ultraphots differed significantly from those of the 1960's. The attachment of the tubehead to the 'stand', for instance, was originally achieved by means of a bayonet mechanism and locked by a lever, instead of the more familiar 'gate and latch', tightened with a knob. The earlier method made it necessary to partly rotate the tubehead, and this required the lower edge of the casting of large format photoheads and rear projection screens to be arched in order to accommodate the movement. Rear projection screens with arched castings continued to be supplied for several years after the need for them had disappeared.
The mirrors which direct the light from the various lamphouses were originally directed via a relatively small Bakelite switch above the right hand lamphouse, but this was later replaced by a chrome plated lever with a black plastic knob.
The outline of the base of the first Ultraphot(s) to be illustrated resembled that of the Universal and Photomicroscope: a circle with the 'sides' removed (i.e, along parallel chords) but, rather regrettably, it was later changed to a rectangular shape with a semi-circle added to each end. The effect of this was to make the instrument appear decidedly 'front-heavy', a state of affairs which remained until the appearance of # lll, when the original outline was restored.
A more significant peculiarity of early Ultraphot ll's (and Photomicroscopes and Standard Universals) was that the nosepiece fitting at the base of the Optovar magnification changer took the form of a 'female' ring dovetail. Nosepieces and epicondensers, with matching male dovetails, had to be pushed upwards from underneath and secured with a knurled screw - not always the safest of procedures. These nosepieces and epicondensers lacked a telan lens, which was located in a slider in the analyser slot, or built into the analyser itself. Both male and female components of the dovetail were transected by a groove which allowed the insertion of a 12mm wide compensator or barrier filter slider from the front right of the instrument.
The introduction, in July 1960 (Circular Letter 16/1960), of a redesigned nosepiece fitting was associated with radical changes to the optical system and marked an important watershed in the development of the 3 largest instruments of the Standard range. The new fitting (in Ultraphots from 55 016 onwards) embraced the now familiar horizontal dovetail mechanism, allowing the fitting of 5 position nosepieces by sliding them forward from the rear left, and single nosepieces and epicondensers, backwards from the front right*4. More importantly, the anterior telan lens was now accommodated within the nosepiece or epicondenser: part of the effort to rationalise the lightpath into and through the tubehead. As well as the redesign of nosepieces, epicondensers, tubehead and Optovar, the changes also necessitated alterations to analysers and barrier filter sliders to accommodate the new arrangement, while subsequently developed accessories which utilised the analyser slot, such as transmitted light D.I.C equipment, could not be retrofitted. Analysers from the earlier period are not, of course, compatible with later instruments - sometimes a source of annoyance and confusion - because they incorporate a telan lens.
'Early' Ultraphot ll's were fitted with more-or less spherical 'high performance' lamphouses, but in Circular Letter no. 6/1960 it was announced that these had been replaced. The new form, which was larger, with 'cooling vanes' and a ventilation chimney, i.e. the well-loved 'football' or 'pumpkin' lamphouse 250, would have the same socket fitting as the earlier model, but different collector lenses.
Before 1962, Ultraphots were basically transmitted light instruments and the internal 'illuminating tube for incident light', necessary for epi-illumination, had to be purchased as an extra. The circular 8/1962 announced that all new Ultraphots, from 58 390 onwards, would be permanently fitted with an improved form of the tube, ex factory.
The Ultraphot ll was originally designed as an exclusively large format camera-microscope, but the increasing popularity of 35mm film for photomicrography led to the introduction of an accessory 35mm photohead (Circular Letter 11/62).
The transmitted light port in the base of early instruments was merely recessed to take a 32 mm diameter filter, but from June 1962 (Circular Letter No.22/1962), a 'supporting ring' was incorporated which would accommodate a stack of several (exciter) filters. It also made possible the automatic centration of the 'Macro Stage', the base of which was now recessed to fit it. Previously, the supporting ring had been a separate accessory.
* 3 See the index page of this website.
* 4 Nosepieces can also be fitted from the front right, but this arrangement makes it difficult to see what is happening on the stage.
|How many transmitted light Nomarski D.I.C. systems did Zeiss design for 'the 160mm tube' - and how do they differ?|
|There appear to have been three basic models:
|The firm's Electrical Safety Officer has removed the plug from my Photomic. l, and put an 'unsafe' sticker on it - the wiring is weird!|
|The mains supply cord used by Zeiss in the 1950's and early '60's would now be considered potentially very dangerous. The earth wire is red, the neutral black and the live blue! Because of the age of the cable, the insulation must be considered suspect anyway and it might be wise to get a competent electrician to rewire it more conventionally.|
|I recently bought a grey substage bracket for my (Met) U/p lll, but my phase contrast condenser won't fit it: the springbolt in the centring ring of the substage bracket is at the back, but the notch on the condenser dovetail ring that it ought to fit in, is at the front! The ring underneath the condenser can't be turned round, to suit, because of the positions of the 3 fixing screws.|
|Your substage bracket is one of the 'short' focusing variety generally found on 'late' Photomic. llls and Universals. So - fitted, a Photomicroscope could be equipped with an Epicondenser lllRS (for epifluorescence) and still have room to focus a condenser (usually phase or D.I.C.) under the stage. 'Turret' condensers manufactured at that time have dovetail rings with notches in both the '12' and '6 o'clock positions, allowing them to be used on both old and new brackets, while simpler condensers had rings without notches.
If your condenser were a D.I.C. version, the only solution to your problem (other than swapping it for a later model) would be to get a skilled machinist to grind another notch in the dovetail ring. For other types of condenser, the exact orientation of the condenser is largely a question of convenience and the presence/absence/position of the notch unimportant.
Generally, I find the short bracket much easier to use than its predecessor, partly because the centring screws are at the front, but mostly because I find it much easier (and less damaging to the underside of the turret) to fit turret condensers by tilting them up at the front and pushing them away from me, than the reverse. Incidentally, on Photomic lll's (and late Universals?) the focusing dovetail slide, to which the stage and substage brackets are attached, has 2 alternative threaded holes for fitting the 'stop' for the substage. The upper position is intended for use with the short bracket, but it is worth while moving the stop to the lower hole if, because of lack of room under the stage, you have difficulty during the fitting of some condensers,. Unless the condenser has a very long focal length, of course, you then have to remember to unclamp the substage bracket and push it back into its proper position under the stage bracket!
|There seems to be a lot of concern about delamination in Zeiss objectives: what is it and what causes it?|
|So-called 'delamination' is the separation of cemented elements, mostly in objectives, but not unknown, as far as Zeiss equipment is concerned, among wide-angle eyepieces, the telan lenses of widefield nosepieces, and Nomarski prisms. It seems to be more prevalent in lenses of more complex construction and, particularly, where a cement other than Canada Balsam has been used. The low power Neofluars, Epiplan HD 100/1.25 oil and all the planapos appear to be prone to it, the 4/0.16 (rear doublet), 40/1.00 oil, 63/1.40 oil and 100/1.30 oil being commonly affected. Unless the condition in an objective is very advanced, it will be necessary to use a Bertrand lens or phase telescope, together with careful focusing and adjustment of the illumination in order to detect it. It will then be seen as a faint (usually)grey film, spreading across one or more elements. Where it is restricted to the outer margins of lenses, it appears to have no effect on the image but, as the area of separation increases, there is progressive loss of contrast and the worst affected objectives are useless.
In the case of the separation occurring within objectives, telan lenses and Nomarski prisms, the most likely culprit is the heating effect of the illumination system. Both filament bulbs and arcs radiate large amounts of infra red and much of this is probably focused in the objective or somewhere close behind it. In busy research and medical screening laboratories (the probable source of many second-hand planapochromats and Neofluars, anyway), microscope lamps may be switched on at 9.00 AM and left on all day, so be particularly careful when buying instruments from them. Since the coefficients of thermal expansion of the metal mounts, glass, and fluorite differ, long-term damage is probably inevitable. The presence of a C-mount adapter among the bits and pieces of an Ultraphot outfit should also set off alarm bells because it usually means that the instrument has been used for cinémicrography - probably with a 12v 100w lamp blazing at full voltage for long periods. I once had a 40/0.75 Neofluar phase contrast objective from such an outfit in which the balsam in the area around the margin of the phase ring had obviously been boiled. In my experience, Ultraphots with a well-used CSI 250W lamp should also be viewed with suspicion. These lamps, together with HBO 200's, and, worse still, XBO 150's, are particularly potent objective cookers since they cannot be dimmed, and are frequently left burning because switching them on and off shortens their life. It is worth noting that neutral density and Polaroid filters are usually almost completely transparent to infra red and so offer no protection to lenses - or eyes*.
As a result of the current 'delamination phobia', even slightly affected lenses are virtually unsaleable, providing excellent opportunities, for those prepared to take a risk, to acquire high quality objective at bargain prices.
What is the risk, anyway? The common assumption, of course, is that separation is a progressive condition which will continue independently of how the lens is treated, but there seems to be no evidence for this. My guess is that, treated prudently, many an apparently doomed planapo will enjoy a longer useful life than its owner!
*Richardson, T. (1997) 'Do You, Your Slides and Your CCD Camera Need Sunglasses?. Proc. Roy. Microsc. Soc. 32 (2) 101 -105.
|The binocular tube of my U/p is very difficult to remove (and even more difficult to replace) even though I fully unscrew the chrome cap from the springbolt on the dovetail ring of the tubehead.|
|The springbolts which are used to secure components fitted with annular dovetails (viewing tubes, phototubes, lamphouses etc.) frequently seize as a result of the oxidation of the grease they contain. As a consequence, such components are commonly difficult to remove without the possibility of damaging them.
They should be treated as follows*1:
*2In the case of the springbolts securing centring stages and condensers, these operations are not possible and remedial action is confined to running a drop of lubricant around the base of the pin, + (4), followed by cleaning with WD40 and repeating the operation until the bolt shoots back immediately after being forced outwards.
|Go to Front Page|