In a previous review, 7x50 binoculars for use under low light conditions were tested. The request for exit pupils as large as 7.1mm leads to either small fields of view or, if an apparent field of 60 degs. or more is wanted, to a sophisticated design with either huge prisms or semi-apochromatic objectives. Many people, however, are never able to make use of such a wide exit pupil because their pupils won't dilate to this size even in total darkness. A binocular of specification 8x50 provides exit pupils of 6.25 mm, still enough for night use, but easier to construct with proper apparent field of views. For example, a manufacturer may produce a 7x50, 8x50 and 10x50, all three of them with identical bodies and same true fields of view, e.g. 7 degs., but different oculars, which then necessarily lead to apparent fields of 70 degs (10x50), 56 degs. (8x50) and only 49 degs. (7x50).
The 8x50 therefore appears to provide a good compromise between low light ability and apparent field of view. In this review, three classical high-end binoculars of this type are compared. Unfortunately, none of them is produced any more, but at least the Docter Nobilem (the former Zeiss Jena Octarem) is still available on the surplus markets, sometimes in brand new condition. Whoever is searching for a current line high end 8x50 will probably fail to find a decently priced Porro glass, but end up with a roof-prism design such as Leica's Ultravid or Swarovski's SLC and will have to pay a premium.
Fig.1: The Zeiss (Oberkochen) 8x50
Towards the end of WWII, Zeiss (Jena) was taken over by the Soviets, whereas a second branch was set up in the Western Zone of occupation to become the "Zeiss-Opton Optische Werkstaette Oberkochen GmbH". The work on binoculars resumed immediately thereafter, so that in 1954 the first new Porro type model, the Zeiss 8x30, was introduced. As can be verified on this list, the first of the 50 mm models, the 7x50, appeared in 1956, followed by the 8x50 and 10x50 in 1957 (the 7x50 B/GA is, with few modifications and with individually focused oculars, still in production). These binoculars employ the idea of air-spaced tele-objectives, where the distance between objective and ocular is smaller than the focal length, leading to the characteristic compact body shape. From 1960 onwards the 8x50 was called 8x50B, with 'B' indicating it to be suitable for eye-glass wearer, but to my knowledge it were only the eye-cups which were then made of rubber to fold down - the ocular construction, with 5 lens-elements (a 2-1-2 design of type Zeiss Astroplanar), remained unchanged. These 50mm Porro binoculars did certainly represent the best glasses made for the civilian market at that time, and nowadays collectors are willing to pay 500 Euro or more for such an item in good condition.
Fig. 2: The Zeiss Jena 8x50 Nobilem Super.
Zeiss Jena began with the development of the 8x50 Nobilem Super (and its brother, the 12x50 Nobilem Spezial) in 1978. It was obviously an attempt to copy the Zeiss Oberkochen models (compare with the early prototype which was even closer to the West-design), but with increased performance parameters like field of view. It was then introduced in 1980 and under production until about 1985. Although being brilliant binoculars, they came up too late: During the 80s, bulky Porro binoculars had gone out of fashion and the era of more compact and elegant roof prisms had begun. The construction of the Nobilem Super, with air spaced teleobjectives and a 5 lens-element ocular (very similar to the Zeiss Oberkochen design) was highly sophisticated and costly even under East German production conditions, and they did never sell as well as expected (and deserved!), despite of the fact that they were second to none in their optical performance. In 1985 they were replaced with the simpler models Octarem and Dodecarem, which, a couple of years later, were again re-named 'Nobilem'. Today, collectors pay 600 Euro or more for these binoculars, and they are difficult to find on the surplus markets.
Fig. 3: The Docter Nobilem 8x50 B/GA (formerly Zeiss Jena Octarem)
When Zeiss Jena in 1985 introduced a new high-end line of Porro Prism binoculars, which originally included the 8x50 Octarem and the 12x50 Dodecarem, they did something very smart: They returned back to the classical design with a long body shape, allowing for longer focal lengths and therefore relaxing the technical requirements inherent in the Nobilem Super without the need to sacrifice optical performance. With somewhat smaller field of view, the ocular construction could be simplified, while, at the same time, the eye-relief could be increased. Additionally, mechanical features were improved: The Octarem and Dodecarem were splash-water proof. The following link contains the scan of an original article printed in the Jenaer Rundschau in 1985 (German language), describing the construction of the Octarem and Dodecarem. These binoculars, shortly after re-named 'Nobilem', were cheap compared to the Nobilem Super, therefore selling better, and later supplemented with 10x50, 7x50, 8x56 and 15x60 models. Some of them are still under production by Docter Optic. In good condition, the 8x50 Octarem/Nobilem today sells for 350 Euro on the second-hand market.
Fig. 4: The Zeiss (Oberkochen), Nobilem Super and Nobilem/Octarem
The following table summarizes some of the specifications of the contenders.
|of view (deg)
|of view (deg)
|CZJ Nobilem Super 8x50
|Docter Nobilem 8x50 B/GA
|Zeiss (Oberkochen) 8x50
Image sharpness: This is a strong side of all three contenders. Especially the Docter and the Zeiss (Oberkochen) offer images which are sharp until close to the edge of field. The star test exhibits the first significant distortions at about 80% (radial) off the center, and even at the edge they remain on a low level. The Nobilem Super, with its wider field, is slightly weaker at the edge, with low-to-moderate distortions, starting from about 70% off-center. This is still an excellent result. During day time observations, the edge distortions remain insignificant in all three binoculars, indicating the high level of optical know how put into these instruments.
Image color: None of these binoculars is totally free of color, but they produce a slight yellowish ('warm') tint of same intensity in these three models. It is not reaching any disturbing level, but becomes visible once a blue sky is observed and its color saturation is compared to the one produced with another binocular of fully neutral color rendition (like the Fujinon 7x50).
Rectilinear distortion: All three binoculars show a slight pincushion distortion. This helps to eliminate the globe effect and produce a smooth image motion when the binocular is panning during terrestrial observations. I found the panning behavior of the Nobilem Super particularly nice, reminding me on the superb characteristics of the 7x40 (Checkpoint-Charlie) binocular of the NVA, but its contenders are not far behind.
Stray light: Light from sources outside the field of view can enter the instrument through large angles and illuminate the internal tube walls, are in parts scattered back into the optical path and produce a diffuse illumination of the image. In many cases, this stray light is visible as a diffuse ring close to the edge of the field. This effect can be observed in the Docter Nobilem, and, to a much lesser extent, in the Zeiss (Oberkochen) and the Nobilem Super. The high level of stray light suppression is again a property the Nobilem Super shares with the 7x40 DF. I suspect that the short body shape of this glass (as well as the Oberkochen's) supports the prevention of this type of diffuse stray light. In contrast, the long tubes of the Docter provide a lot of inner-wall area to be illuminated, and despite of the existing baffles, some residual stray light is able to enter the light path. In my opinion, this is the only significant weakness of the Docter Nobilem 8x50.
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. The suppression of this type of reflections can serve as an indicator for the quality of anti-reflection coating. In fact, the Zeiss (Oberkochen), being the oldest binocular and the only one with singly coated lenses, has some trouble, especially if the light source is very bright. The produced ghost images are highly diffusive - perhaps produced at the air space between the objective lens-elements - and thereby reducing the image contrast. This effect is visible when observing the moon, so that the surrounding sky does not come out as black as it should. The Docter Nobilem produces a single, well localized ghost image of low-to-moderate intensity and red color, which is not affecting the overall contrast of the image. Surprisingly, the Nobilem Super performs even better. Ghost images show up only at high intensity and remain on a lower level than the Docter's. I do not believe that the coating of the Docter Nobilem is in any aspect inferior to the Nobilem's (Super), but the particular ocular construction of the Docter may promote the creation of the single ghost image as described above.
Low light performance: These are binoculars with large exit pupils and therefore specialists for low light applications. It is interesting to find the Docter Nobilem clearly performing best in this discipline. Even under daylight, its image appears to be slightly brighter than the Nobilem's (Super), and visibly brighter than the Zeiss (Oberkochen). Under very low light the Docter is able to resolve details which are not as clearly discernible in the Nobilem Super. The light transmission of a binocular depends to a large extent on the quality of coating, but also on the number of optical elements to be passed, and here the Docter is certainly in a better position. Its objectives are not air spaced, the ocular construction is simpler, with less number of lens-elements, and the prisms are cemented to avoid another air-to-glass transit. This may be the reason for the excellent low light performance of the Docter, which comes very close to the 7x50 Fujinon FMT-SX. The Zeiss (Oberkochen) is not fully competitive here. The combination of a sophisticated design (and therefore many lens-elements) and its simple coating lead to a visible reduction of light transmission.
|CZJ Nobilem Super 8x50
|Docter Nobilem 8x50 B/GA
|Zeiss (Oberkochen) 8x50
The 'final score' is the sum of the individual scores and is intended to serve as an orientation only.
It is fair to announce two winners of this competition. Although both Nobilems differ among each other in many details, it appears impossible to judge which of them is the better one. The Nobilem Super has got the wider field, a better stray light suppression and has got the edge in ghost image suppression, whereas the Nobilem/Octarem has got a better edge-sharpness, a brighter image and is better sealed against the weather. The Nobilem Super is perhaps the more spectacular binocular: Zeiss (Jena) has pushed its construction to the technical limits to gain a few extra degs. field of view and still keep the body short and compact. The later Nobilem/Octarem design was much more conventional, less compact, but cheaper, at the same time fault tolerant and altogether hardly behind the 'Super' in its optical abilities. When it comes to performance/price, the Nobilem/Octarem is surely the better choice. This is all the more true for today's surplus markets, where collectors have driven the price of the Nobilem Super into astronomical dimensions. In fact it is quite difficult to find this instrument at all, and there are binocular fans who did never hold the Nobilem Super in their hands.
Whoever feels sorry about that should be reminded on the recently introduced Miyauchi 7x50 Binon, which as well combines the features of large exit pupils with a wide angle. In a straight comparison, the edge sharpness of the Nobilem Super is better than the Miyauchi's, and they are an even match in stray light suppression, but in all other disciplines the Miyauchi is at least a little bit ahead of the Zeiss Jena glass. I think the Miyauchi could be regarded as a suitable replacement for the Nobilem Super.
The Zeiss (Oberkochen) 8x50 is actually not far behind its younger competitors. If equipped with a state of the art coating, this design could still compete with any other high end binocular available these days. The Zeiss also proves that Porro type binoculars do not necessarily need to be heavy and bulky. The Leica 8x50 Ultravid weights 1.0 kg, the Trinovid and the Swarovski SLC are with 1.15 kg even heavier than the Zeiss. To be fair, one should mention that these roof-type binoculars are waterproof, but not every user urgently needs such a feature. I hope that once upon a time a manufacturer decides to pick up this design and produces a modern 8x50 Porro prism binocular, with a reasonable price tag (which could be around 700 Euro), and on a quality level of this old Zeiss.
Docter Optics (USA agent), producing the Nobilem line
Zeiss (Oberkochen) 8x50 on Fan Tao's page
Docter 8x50 Nobilem/Octarem on Fan Tao's page
Zeiss (Jena) 8x50 Nobilem Super on Fan Tao's page
Last updated: Jan 2005