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Binoculars review

Carl Zeiss Jena Jenoptem 7x50

Carl Zeiss Jena Jenoptem 7x50
7 September 2014
Optyczne.pl 
The history of the 7x50 binoculars, produced in Jena, starts in 1919 when the Carl Zeiss Jena Binoctar was launched. It was equipped with an individual focusing system. The Binoctem model, with an ocular bridge, making the central focusing possible, hit the shelves only in 1931. It underwent several slight modifications of the casing and was produced in more or less unchanged form until the 70s of the 20th century, when the T3M coatings were added. Then, for some time, it existed on the market side by side with its twin model, the Carl Zeiss Jena Jenoptem 7x50. Its production lasted till 1990 when the Jena factory was overtaken by the Analytik Jena, the owner of the Docter brandname.

The model we are testing here was produced in 1985 and, despite those 30 years that passed, it is very well-preserved. Of course it features the T3M coatings.

Apart from the binoculars buyers got in the box a leather strap and a soft, leather pouch with its own strap. There are no caps for objective lenses or oculars included.

Pictures
  • Lornetka Carl Zeiss Jena Jenoptem 7x50
  • Lornetka Carl Zeiss Jena Jenoptem 7x50
  • Lornetka Carl Zeiss Jena Jenoptem 7x50
  • Lornetka Carl Zeiss Jena Jenoptem 7x50
Manufacturer data

Manufacturer:

Carl Zeiss Jena
web site

Distribution / Sales:

komis, gie│da, aukcje
web site

Magnification Lens diameter Angular field of view Prisms Eye relief Weight Price
7 50 128/1000(7.3o) Bak-4/Porro 12 mm 1010 g 800 PLN
Results of the review
Real front lens diameter Left:   50+/- 0.05 mm
Right:  50+/- 0.05 mm
8 / 8.0 pkt
Real magnification 6.96+/- 0.05x 3/3.0
Transmission 81.5+/- 1.5% 10/25.0
Chromatic aberration Slight in the centre and on the edge. 7.6/10.0
Astigmatism Moderate. 6.7/10.0
Distortion The distance of the first curved line from the field centre compared to the field of vision radius: 30% +/- 4% 2.5/10.0
Coma Starts near 65% from the field centre and is medium on the edge. 7/10.0
Blurring at the edge of the FOV The blur occurs in a distance of 73% +/- 3% from the field of view centre. 4/10.0
Darkening at the edge the FOV Slight. 4/5.0
Whiteness of the image Distinct yellow. The transmission curve with a peak near 550 nm. 1.5/5.0
Collimation Perfect. 5/5.0
Internal reflections
Left: Right:
Carl Zeiss Jena Jenoptem 7x50 - Internal reflections - Left Carl Zeiss Jena Jenoptem 7x50 - Internal reflections - Right
A lot of reflections near the prisms.
2.3/5.0
Housing A classic Porro construction – made of metal plus quasi-leather padding. Comfortable to hold. Hard eyecups, a bit too small and without any regulation. 6.5/8.0
Focusing Very narrow central wheel with fine ribbing. It moves lightly and smoothly (full turn takes 360 degrees). A classic ocular bridge which works evenly; you can defocus the binoculars only by applying a lot of pressure on it. Individual focusing on the right ocular – it is smooth to turn but it moves the whole ocular as well. You can notice some grease next to oculars. 3.5/5.0
Tripod A pipe in the centre of the binoculars where you can attach an adapter. 1/3.0
Interpupilary distance from 47.3 to 75.7mm 6/6.0
Closest focusing distance 3.90 m 1.5/2.0
Eyepieces FOV Apparent field of view of 50.3 deg (according to simple formula) and 47.4 deg (according to tangent formula). 4/20.0
Field of view Measured by us amounted to 7.23 +/- 0.04 degrees and was slightly narrower than stated in the specifications. A typical field for this class of equipment. 5.5/8.0
Quality of the interior of the barrels Black and matt tubes and the bottom. Some specks of dust. No scratches. A lot of modern producers could take a leaf out of Jenoptem’s book… 4.6/5.0
Vignetting
Left: Right:
Carl Zeiss Jena Jenoptem 7x50 - Vignetting - Left Carl Zeiss Jena Jenoptem 7x50 - Vignetting - Right
OL: 0.3%, OR: 0.5%
7.5/8.0
Prisms quality Good quality BaK-4. 8/8.0
Antireflection coatings Orange-pink on objective lenses and oculars, purple on the prisms. Medium intensity. 4.5/5.0
Warranty [years] 1 1/6.0
Final result
60.6%
115.2 / 190 pkt
Econo result 0pkt.

Summary

Pros:
  • classic and solid casing,
  • slight coma,
  • moderate astigmatism,
  • good control of the chromatic aberration,
  • not especially bothersome brightness loss at the egde of FOV,
  • good darkening inside the binoculars,
  • very wide range of IPD,
  • good quality BaK-4 prisms,
  • almost circular exit pupils.

Cons:
  • distinctly yellow cast of the image,
  • huge distortion,
  • too many flares near the prisms,
  • not very comfortable eye relief,
  • image on the edge of the field could have been sharper.


Carl Zeiss Jenoptem 7x50 and Nikon 7x50 IF HP WP Tropical


Some time ago we tested the Carl Zeiss Jena Binoctem 7x50 binoculars – an older but equally well-preserved model from 1968 so an era when they still used single layer coatings. That device got a very decent result of over 107 points in our test but, in order to assess thoroughly the Jena factory production we decided to check a newer model, the Carl Zeiss Jena Jenoptem 7x50, already featuring the multilayer coatings.

As we already mentioned the coatings, let’s see how they influence the transmission.


The graph above shows the main difference between the newer Jenoptem and the older Binoctem: in the case of the older model the transmission never exceeded 80%, in the newer one it reaches almost 85%. There is a huge difference when it comes to purple light results – the transmission gets to 55% there while the old Binoctem had it on a level of just 40%. Still you have to mention the fact that the colour rendition remains bad; the Jena multi-coatings were optimized only for the centre of the visible spectrum so, as a result, the difference between the transmission of yellow and blue light amounts to over 20%.

The next difference which sticks out is the appearance of the exit pupils. Over the years the Jena factories changed the way they fixed prisms inside the tubes – from more to less vignetting-prone. It can be noticed: the pupils of the new model are almost perfectly round, the old one had them noticeably truncated.

As the optics (apart from the coatings) didn’t change much, the performance of both models is quite similar: they correct most of optical aberrations in the same way. They should be also praised for the good correction of the chromatic aberration, the coma and astigmatism.

Taking into account the coating and prism fixing innovations, the better result of the Jenoptem 7x50 doesn’t surprise us. What’s more, it is also a very sensible result. Still you should remember that the Jenoptem 7x50 in mint condition can cost as much as about 250 Euro. For such an amount of money you can buy two pairs of the Delta Optical Titanium 7x50, a device with a wider field of view and a better result in our test. The same 250 Euro is enough to buy you the Vixen Forest 7x50, a pair of binoculars we haven’t tested yet but one which enjoys a very favourable opinion of the users.

However it’s always worth to browse second-hand shops and Internet auction sites. If you manage to find a Jenoptem 7x50 in perfect condition for less than 200 Euro it is certainly a good bargain; you can be sure the binoculars will serve you satisfactorily for many years.