The System II represents a fundamental change in B&L integrated photomicrographic cameras. Sleeker than the early DynaZoom camera but far more substantial than the later versions, the System II is a step back to the design principles that required a focusing system. It was necessary for the System II to feature a focusing lens system because the unit was intended to be a new universal device for all (camera ready) professional B&L lines, including the earlier DynaZoom/DynOptic lines. Despite maintaining the compatibility of the system with earlier stands, once more the camera backs required are not compatible with previous versions (although they do come in all previous formats).
The opticians behind the System II seemingly asked themselves ‘how can we make this the last camera a microscopist will need?’ and set about answering it. The systems chief major departure is the coupler, specifically its diameter. At 7/8ths it’s a full quarter inch larger than the previous model DynaZoom camera, and a return to the large size used with focusing DynaZoom cameras. Care was also taken in the design of the coupler, it was made to be removed and a number of versions of the coupler were made, some making allowance for the use of a manual exposure meter.
Once more the camera back attachment point was redesigned. The new male dovetail fitting was made a bit smaller than those used previously and unlike previous models did not feature an alignment screw that required the female dovetail camera back be fixed in relation to the camera. Additionally, where earlier camera backs used two thumb screws the new versions used only one; making it a simple thing to orient the photosensitive surface however one wished without being forced to suffer an inconvenient shutter release or winder position.
Couplers and Camera Backs
Three couplers are known of: the silver Bal-Coated male dovetail∗, the black lens-less male dovetail, and the eyepiece mount†. The silver dovetail makes good use of a Bal-Coated lens to eliminate errant reflection which can prove frustrating with uncoated optics and both it and the black dovetail carry a small slot in the dovetail that mates with the camera. This slot may be turned to align with a similar slot in the System II or turned so as to exclude all light. The purpose of the slot is to permit the insertion of the B&L Cat. # 421240 exposure meters sensor.
The versions are discrete rather than explicit, which is to say there is not any particular model number to distinguish them that is official but they are readily identifiable. One sort is focusable from below 3x to over 10x. On these models only four magnifications are marked: 3x, 5x, 7.5x, and 10x. Two versions of this sort are known, one having an all black shutter speed selector and the other having a silver ring. An additional version, and perhaps more desirable (if less common) one has the same range but is marked in one unit increments from 0-25x with every fifth mark being numbered.
Apart from the previously mentioned camera backs a number of accessories were produced. Special viewfinder adapter plates and eyepieces were available for the various camera backs. It should be noted that these eyepieces were not the film area viewfinder eyepieces that would show the field that would be covered by various popular film sizes. Extension tubes were also available that would extend the distance between the final lens element of the shutter assembly and the camera back. Tubes were made in 2.5x and 5x lengths were produced and could be used in various combinations where special needs required.
∗It should be noted that the connection to the shutter in all cases is a male dovetail and the designation here refers to the connection to the microscope photo-port.
†I’ve seen one in use during the course of a museum visit although I’d be hard pressed to say if it were an actually B&L item or the product of a machinist and a tight budget.