Review: Zeiss Dienstglas 8x30 vs. Hensoldt DF 8x30 vs. Steiner Fero-D 12

by Holger Merlitz

In recent days, binoculars of the German Bundeswehr are showing up rather frequently on the surplus markets. Old stocks are being cleared, because firstly the Bundeswehr is running out of money and secondly these binoculars are technically outdated: New standards require the presence of laser protection filters which can not be fitted to ancient optical equipment. These are good times to purchase cheap but robust second hand binoculars, and also to gain insights into quality standards of the optical devices used during the cold war era.

This review compares three binoculars with specifications 8x30, since decades a standard size for compact and lightweight glasses. They cover the period from the 1950's to the late 1980's, when the new Hensoldt Fero-D 16 with laser protection filters started to replace the older models.

Fig. 1: The Zeiss Dienstglas 8x30

After WW II, parts of the Carl Zeiss Jena staff were transfered to the Western Zone of occupation to initialize the foundation of the "Zeiss-Opton Optische Werkstaette Oberkochen GmbH". It started production in 1947. The 8x30 was the first binocular developed in Oberkochen and in production from 1954 onwards. It became, along with another 6x30 model and shortly before the 8x30 Hensoldt, the first binocular introduced to the re-installed German army. According to Seeger ('Military Binoculars and Telescopes for Land, Air and Sea Service', p. 111) these binoculars were delivered with a partial rubber armor, but those I have seen on Ebay were without, so I guess the rubber had decomposed over the years and was removed. This Zeiss Dienstglas has got a characteristic short body, with spaced objectives and a 6-lens ocular design. It was apparently in service with the German Border Control until recent years. On Ebay it is occasionally seen for about 80 Euro.

Fig. 2: The Hensoldt DF 8x30

The Hensoldt DF 8x30 was introduced to the Bundeswehr in 1955, i.e. just after Zeiss had started to deliver its Dienstglas. Why there was this confusion is unclear to me - however, Zeiss had acquired a majority stock holding in Hensoldt in 1954, so to some extent the DF could be regarded as 'in-house', and it is possible that the demand for binoculars during the early years of the Bundeswehr was too high to be satisfied by Zeiss alone. Also, Hensoldt could offer further models like the 7x50 and 10x50, which were then still out of reach for Zeiss (in 1957, Zeiss introduced 8x50 and 10x50 units). For some years both the Zeiss and the Hensoldt were delivered to the armed forces. The fully rubber armored version appeared in 1959 and remained in production until 1963. In another review the DF was compared to the East German EDF 7x40 and the Russian BPO 7x30. In reasonable condition, the Hensoldt can be found on Ebay for 120-150 Euro, or, usually in better condition, at Deutsche Optik (see link below).

Fig. 3: The Steiner 8x30 Fero-D 12

The Fero-D 12 was made by Steiner, Bayreuth, and, according to Seeger, delivered to the armed forces from 1966 to about 1972. It was an attempt to cut down expenses, which were pretty high with the Hensoldt devices. It was also an experiment to introduce a high performance plastic (Makrolon) material for the body, which then was of lower weight and perfectly sealed against environmental hazards. The Steiner glasses were nitrogen filled and water proof. From today's point of view, however, one can safely claim that this experiment failed. The mechanical construction of this binocular turned out to be insufficient for the daily abuse during military service. Once out of collimation, it was hard to repair, and the number of items 'lost in action' led to a drain of property which was as high as with the more expensive, but maintainable Hensoldt devices. Today, the Bundeswehr has turned back to Hensoldt with its Fero-D 16. The Steiner is frequently found on Ebay and sold for about 80 Euro.

Fig. 4: The Zeiss Dienstglas, Hensoldt DF, Steiner Fero-D 12

The following table summarizes some of the specifications of the contenders.


  Real angle Apparent angle Eye relief Exit pupil Weight
  of view (deg) of view (deg) (mm) diam. (mm) (kg)
Hensoldt 8x30 8 64 12 3.8 0.65
Zeiss 8x30 8 64 9 3.8 0.5
Steiner 8x30 6.9 55 12(a) 3.8 0.5

a: Estimate; exact value unknown


Optical performance

Angle of view: The Hensoldt is specified to have 8.5 degs., but the actual value is just 8 degs., as can be easily checked at the night sky with the bottom of big dipper (7.9 degs.). The same field is shown through the Zeiss, which also displays a nicely crisp field stop. The apparent angle of view then amounts to 64 degs. for both glasses, which qualifies them to carry the label 'wide angle'. The Steiner's field is significantly narrower. 55 degs. apparent field of view is not much for a binocular of this specification.

Image sharpness: As can be expected for any binocular of even moderate quality, the center sharpness is flawless in these three devices. Stars look point-like and without any visible distortions. Close to the edge, aberrations become dominant, and the stars are looking grossly deformed through the Hensoldt and the Steiner. A surprise is the good performance of the Zeiss: From center to almost 70% (radial) toward the edge, sharpness is very high, and beyond 70% the distortions only gradually show up, with a still moderate sharpness at the edge. The Hensoldt has got about 70% of sharp field, too, but then the image is degrading faster compared to the Zeiss. The performance of the Steiner is somewhat disappointing: The image is sharp within 60%, and then fairly quickly degrading to become poor close to the edge. I call it disappointing because with its narrow field one should have expected a more successful control of aberrations.

Image color: The differences are small. In a straight comparison it became obvious that the Zeiss has got a slight yellow tint (one reader told me that such a tint in Zeiss is often caused by yellowing of the canada balsam over the years). The Steiner and Hensoldt are closer to neutral, with the Hensoldt a tiny step toward the blue, compared to the Steiner. I found it difficult to decide which of these two was actually 'neutral', the impression also depends to some extent on the light conditions. After a couple of checks with a white paper, I decided that the Steiner was closest to neutral, followed by the Hensoldt (slightly blue) and the Zeiss (visibly yellowish).

Rectilinear distortion: All three binoculars show a slight pincushion distortion, which is intentionally installed to eliminate the globe effect and hence provide a smooth panning behavior of the image.

Stray light: Under difficult viewing conditions, especially at twilight, light from sources outside the field can enter the objective lenses through a large angle to illuminate the tube walls and is, partially, scattered into the optical path. It then enters the observer's eyes as a diffuse illumination of the image, reducing the contrast. This effect can be on a disturbing level in both the Zeiss and the Steiner. Through the Hensoldt, stray light is detectable, too, but it remains confined to a region close to the edge of the field, creating a diffuse ring of light, but leaving the central part of the field untouched. Under those conditions the Hensoldt therefore retains an image of high contrast, where the Zeiss and Steiner are suffering from noise.

Ghost images: If, at night, a bright object (street lantern, moon) is positioned into the field, reflections on the air-to-glass surfaces take place, which can lead to multiple 'ghost' images of the light source. These military glasses have got a reticle in the right hand side ocular, which can produce an extra reflection, and this is clearly visible in all three contenders. Through the left ocular, the Zeiss and Hensoldt display ghosting on a low level. The reticle in the Hensoldt however is producing a bright spot of reflected light. A similar effect is there with the Zeiss, but the same spot is rather dim. This could indicate a better coating of the reticle, but also differences in the ocular construction. The Steiner exhibits some more serious effects. Especially if the light source is shifted out of the center of the field, a couple of ring-shaped reflections show up which spoil major parts of the image. This effect is present through both of the tubes.

Low light performance: None of these binoculars is made to perform well in low light conditions. With exit pupils of 3.8 mm these are compact devices for use under daylight. Still, a full moon night provides enough illumination for them to function fairly well. I could not detect any significant differences in brightness or contrast between them. Although, in certain situations like twilight, when the sky served as a residual light sources, the Hensoldt had got some advantage in contrast (see stray light section), this was of no relevance under (almost) night conditions.

Mechanical construction

The Hensoldt has got everything a military binocular needs for (ab)use under rugged conditions: A solid metallic body, protected with a thick rubber armor, precisely machined moving parts and individually focusing oculars, hence well sealed against water and dust. The same holds for the Zeiss - except for the missing rubber armor, making it more prone to potential damage in case of hard mechanical impacts. The Steiner is a difficult case: Among the competitors, it is perhaps sealed best against water. The body is not of metal but Makrolon, which is nevertheless quite impact resistant. Still, experience has shown that irreversible damages happened in a frequency which was intolerable for a military device. The overall mechanical ruggedness is therefore not on the same level as it is with the Hensoldt.

Summary

The following table is supposed to summarize the above observations. The best performing binocular gets three points, the following contenders two and one, respectively. In case several binoculars are ranking equally, their scores are averaged.


  Angle of Image Stray Ghost Low Image Mechanical Final
  field sharpness light image light color construction score
Hensoldt 8x30 2.5 2 3 2 2 2 3 16.5
Zeiss 8x30 2.5 3 1.5 3 2 1 1.5 14.5
Steiner 8x30 1 1 1.5 1 2 3 1.5 11



The 'final score' is the sum of the individual scores and is intended to serve as an orientation only. For a few additional hints, I refer to the binocular application profiles.

The Hensoldt DF probably displays the most complete design among the competitors. It exhibits no really weak point and is well balanced between the various optical features, and also mechanically it is equipped to survive the conditions of military service. Otherwise, repair was easy and usually successful, and it was perhaps this combination of features that finally led to the decision to keep hold on Hensoldt and, in present days, to purchase the Fero-D 16 from Hensoldt again as a replacement for the 8x30 DF. Still, when comparing this binocular to those devices employed in the Warsaw Pact, one has to appreciate that somehow these were more sophisticated machines, with long eye-relief for gas mask use, with infrared detector, reticle sometimes with illumination and superior low light capabilities. If not for anything else, for military optics there was apparently enough money available in the East block.

The Zeiss Dienstglas showed up with a surprising performance. In parts, it offered the Hensoldt a stiff competition, and in some disciplines like (edge-)sharpness and ghost image suppression it turned out to be the winner. On the down side, the image has got a slight yellow tint and is, under certain conditions, suffering from noise due to stray light. The latter may well be spurious, because this sample was heavily used and some cleaning marks and a little haze inside might possibly have caused a performance loss. What is missing is the full body rubber protection. Altogether, this is a binocular which is nowadays still useful for civilian applications; its very compact size and low weight make it an ideal companion on a long walk, and it is certainly more rugged than most other binoculars of this price sector.

While the Hensoldt and Zeiss were competitors on the same level, the Steiner Fero-D 12 could not reach up to the quality standards set by these older designs. Not that this was a big surprise: This glass was intended to be a cheap alternative to the Hensoldt, and as such one should not expect the same performance level throughout. You get what you pay for. Still, the gap to the Hensoldt was a little wider than expected, and too much to be tolerated as a compromise in price/performance. Even at the time of introduction in 1966, this Steiner was clearly inferior to the state of the art in optical design, and this was, apart from its mechanical deficiencies, maybe too less to permanently replace Hensoldt as a supplier of binoculars for the armed forces.

Disclaimer

The information given in this report reflects the personal impression and opinion of the author only. I cannot guarantee for the accuracy of any given specification. I have neither been payed nor have I been supported in any other way to write this review.

Links

Carl Zeiss - A history of a most respected name in optics, a great article by Martin C. Cohen.

Zeiss 8x30 on Fan Tao's page

Deutsche Optik, selling the DF 8x30

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Last updated: 2004