| Accessories for close-up work
Taking pictures with short subject to lens distances any wide image scale demonstrates the close-up work by SLRs. Even difficult close-ups will become possible by fitting standard extension lengthening devices between camera and lens. Unobjectionable focusing is guaranteed by the bright finder image for extreme cases, too. With the Pentagon 6, Pentagon 6 TL, and Praktisix there are no problems of parallax otherwise connected with short subject to lens distances. The below mentioned accessories can be used for the Pentagon 6, Pentagon 6 TL, and Praktisix cameras as well.
| Close-up's taken with extension rings without plunger.
(order No. 208530)
The helical thread of the standard lenses allows to approach to subject up to about 1 meter while for pictures at shorter distances you need extension rings. Such rings, used singly or in combination, are fitted between camera and lens. The rings A and B (9 mm each) are always required to connect camera and lens. The rings A, B, 1,2, and 3 altogether bring about the image scale of 1. The special extension ring Z (order No. 208560) serves for the connection of a twin cable release (order No. 210050) which will be necessary to maintain the effect of automatic diaphragm control also for close-ups. In such cases the twin cable release will control diaphragm in the lens and will subsequently release the shutter. For this purpose the adjusting screws of the twin cable release are set so that first the diaphragm will be closed down to the preset value and then the shutter will be allowed to run down. Table 1 lists the extension tubes which may be combined, the lens to subject distances, the prolongation factors, etc..
Table 1 close-up's taken by extension lenses without plunger
Extension ring A = 9 mm
Extension ring B = 9 mm
Extension ring I = 8 mm
Extension ring II = 16 mm
Extension ring III = 32 mm
Extension ring Z = 920 mm
These values apply to the Jena Bm 80 f2.8 lens. For other lenses of equal focal length slight deviations will result.
*with special extension ring(Z)
| Close-up's taken by extension rings with plunger.
(order No. 208810)
The plunger type extension rings allow to take close-ups at full utilization of the automatic diaphragm control without any other attachments. The small plunger in any ring provides the connection between the automatic diaphragm control system of the lens and the rocker of the camera by which is control is actuated. Extension rings of this type will be of the special advantage when shooting moving subjects.
One set of plunger type extension rings comprises 4 separate rings, viz.
ring 1=15 mm
ring 2 = 22.5 mm
ring 3 = 30mm
ring 4 = 60mm
Operation of the automatic diaphragm control system is guaranteed for all combinations listed in table 2.
In conjunction with the 80-mm f2.8 standard lens, photos with image scales between 0.12 and 1.62 may be taken. From table 3 you'll read some values recommended for close-upswith lenses of 65, 80 and 120mm f.
The 1Omm plunger type extension ring provided with a spring actuated clamping bayonet(order No. 208811) is not intended to be combined with other extension rings, it merely fills the gap in the image scale between 0.1 and 0.18,i.e. the maximum extension of the lens (8.5mm) and the No. 1 extension ring (15 mm)-cp. Table 2. If this ring is the first one to be screwed to the camera you should release the shutter before the lens is inserted and locked
| Close-up's taken with the aid of the close-up bellows
(order No. 208750)
When using the close-up bellows attachment you can set all the extensions according to the division on the guide bar (20mm to 100mm). They will be no gap and with the 80mm after standard lens thus you will obtain image scales between 0.25 and 1.25. Operation of the automatic diaphragm control (of importance for moving subjects) is maintain effective by using the close-up bellows attachment in combination with a twin cable release (order No. 210050). The adjusting screws are set so that actuation of the release first the diaphragm is closed down to the preset value and then the shutter releases (figure 4). The close-up bellows attachment is fixed on tripod through the tripod thread provided on the movable part (lens support). This arrangement keeps a subject to lens distance constant in focusing. You'll be better, however, to use the focusing slide (order No. 208201) which enables you to preset the image scale and focus with the eight of the focusing slide. With reversing to (order No. 208780) intended for the lenses Jena Bm 80mm f2.8 and Jena T 80f2.8 focusing will become possible even up to the image scale of 2. The filter thread of the lenses fastened on reversing tube with the back lens being directed towards the subject (figure 5). This kind of lens arrangement is taken into consideration in the values given in table 4 (usage of the reversing tube),i.e. for this distance which is between the subject to be taken and back lens. This arrangement is recommended for wide extensions (image scale above 1) since lenses, in general, are corrected for long subject distances. Operation of the automatic's spring diaphragm is maintained by the twin cable release in conjunction with a special extension ring (order No. 208360). The values of free distances listed in column 3 of table 4 are reduced by about 18mm through the above-mentioned extension ring. The values of table 4 apply to the close-up bellows attachment being used in combination with standard lens Jena Bm 80mm f2.8. For other lenses of equal focal length there are slight variations, and the gap between the image scale 0.1 and 0.25 can be filled in most cases by the 10mm plunger type extension ring B means of this ring in the helical thread of the lens the image scale can be set between 0.12 and 0.22. Operation of the automatic spring diaphragm is maintained by a plunger provided in this extension ring (without twin cable release). For image scales and elongation figures please see tables 2 and 3. Any computation regarding the elongation factor will be omitted if the TL prism attachment (order No. 207520) is utilized for exposure metering because the attachment allows two meter only that light which really contributes to picture composition, regardless of the accessories applied. More details please find in the appropriate leaflets.
|Table 2 Close-up by extension rings with plunger
The values below apply to Jena Bm 80mm f2.8 lens. For other lenses of equal length slight deviations will result.
|Table 3 Image scale and prolongation factor for some lenses of different focal length.|
|table 4 Close-up's taken by the close-up bellows
Values below apply to Jena Bm 80mm f2.8 lens. For other lenses of equal length slight deviations will result.
|Focusing and framing systems
Field lens, ground glass (order No. 207750)
figure 7 Suited for photographs except of special work.
Field lens with measuring wedge, ground glass (order No. 207370)
figure 8 Suited for photographs except of special work. The measuring wedge corresponds to the coupled split image rangefinder principal.
Fresnel lens with microprism screen and ground glass ring (order No. 207251)
figure 9 Suited for photographs except of special work. Focusing is either by microprism screen or ground glass ring. Particularly good brightness of finder image due to Fresnel lens.
For special photographic work the following focusing systems are available:
Field lens with 10mm grid, ground glass (order No. 207340)
figure 10 Used for reproduction work and all pictures of which exact aligning of the camera will be necessary (to avoid ,e.g. converging lines in architectural photography).
Field lens with bisecting lines and 5mm division, ground glass (order No. 207360)
figure 11 recommended for pictures for which a certain image scale should be observed, e.g. for reproduction work and photogrammetry.
Field lens with bisecting lines and 5mm division, clear glass (order No. 207350)
figure 12 destined for photo micrograms of high enlargement as well as in combination with medical apparatus, such as endoscopes etc. where a picture of the light intensity will be available
Field lens with Clearfield and bisecting lines, ground glass (order No. 207330)
figure 13 suited for close-up's and photo micrograms. The bright aerial picture and hairline cross assist in focusing. The field lenses are exchanged as described below: if a field lens fitted in the camera shall be exchanged for another one, the viewfinder is put off and then the screws of the three retaining angles are slackend with the aid of a small screwdriver. So, the springs can be turned to the side and the field lens, after having removed the circlip, is carefully allowed to fall out. Another field lens is mounted in reverse order by observing that thin edge of the field lens directs the rear. Attention: Fresnel lenses and all other field lenses are provided with differing retaining clips and circlips. We recommend to have the lens exchanged by a photo dealer or machinition, if necessary.
|The magnifier attachment (order No. 208760)
the magnifier fitted in the finder will not meet every and all requirements. For this reason the magnifier attachment is used, to improve focusing, particular close-up. It is fastened on the camera instead of the magnifier or prism attachment. Magnification of the ground glass image will be 3.6. And when used with an eyesight correction lens, ranging from minus 4 to plus 2, wrong sighted persons will also be able to focus exactly. The magnifier is covered by a rotatable eyecup which excludes disturbing stray light.
|Special pressure plate for photographic plates (order No.
with inserting a special pressure plate (figure 16) you'll be enabled to use material, probably of the 6.5cm X 9cm size, without any plate adapter. The rather sturdy pressure plate intended for pressing down the film is substituted by a thinner pressure plate. You can exchange the plates by yourself by carefully observing not to deform the pressure springs. This applies particularly to the spring of the film pressure plate since variation of the compression force influence the plane condition of the film and its advance. Due to the differences in position of the film and plate, resp. It will be necessary to correct the set distance value before taking. You should approach the lens by about 0.1 m more to the plate, i.e. you should replace the mm values of distance scale of the lens by the mm values below: "aus Jena Bm" 80mm f2.8 2.3mm "aus Jena T" 80mm f2.8 2.3mm when setting to infinity this correction will be possible no more due to the stop. To obtain in spite of this a distinct picture we recommend to set the diaphragm to a new hall higher than.