A Closer Look at Two Compact Porro Classics.

The Carl Zeiss Jenoptem 8 x 30W(left) and the Opticron Dioptron 8 x 32(right).

A Work Commenced April 24 2022

 

I don’t suppose you’ve noticed, but I’ve taken rather a shine to a number of compact porro prism binoculars of late, having spent the vast majority of my time exploring roof prism models. After having test driven a few models now, I’m rather taken by their considerable charms, not least of which is their simple design, excellent optics, and much smaller price tags than similar quality roofs. Before I pulled the trigger on a few top rated models, I took some time to get a feel for a couple of classic models in the 8x 30/32mm aperture class. Accordingly, I bought up two models on the second-hand market for field testing; the Carl Zeiss Jenoptem 8 x 30 and the Opticron Dioptron 8 x 32, as shown above. In this short blog, I’d like to relate some details about these two models and how they perform after all these years.

I purchased both models from ebay. There were many Zeiss DDR Jenoptem models available for sale in all sorts of condition. That helps stabilise their market price to between about £60 and £100 UK. I settled on a late-1980s model(serial # 6722320), with the famous T3M multi-coatings, which, for their day, were well ahead of anything else on the market.  The unit I purchased was in excellent working condition, without any visible damage to the optics, and devoid of internal fungus infestations. The binocular came in its original brown leather case, which needs a few stitches to restore it to full working order, as well as a nice leather lanyard.

The c.1988 Carl Zeiss Jena Jenoptem 8x 30 ocular lenses with famous T3M multi-coating.

The objectives looked pristine after I gave them a thorough clean:

The well preserved anti-reflection coatings on the 30mm objectives. Note the serial number indicative of the era in which it was manufactured.

Some background research informed me that the leather case originally supplied with the instrument was lined in a fetching rose-coloured lining:

The original case, with its nice rose coloured lining.

The instrument arrived well collimated. The central focus wheel operated smoothly, with no free play or backlash. I was very impressed when I took my first look through it. The image was bright and very sharp within its very generous sweet spot. I was especially taken aback by the enormous field of view; fully 8.4 angular degrees! The dioptre compensation ring, located under the right ocular, moved smoothly but was easily nudged out of place.

Observing in an open field, in bright, spring daylight, showed that glare was quite well controlled but certainly more than I’ve seen in most modern instruments. Still, the sheer majesty factor of the field of view made a very deep impression on me. I was especially taken by the wonderful 3D pop to the images, which I found very engaging. As this instrument was more than 30 years old, I was expecting some internal reflections when I turned the instrument on a bright light source; and rest assured, a few did show up.

The instrument presented a very warm image but it was not as yellow as other reports have suggested. Maybe this was because I had a quite late model of this world famous binocular – I’m not entirely sure- but I was surprised to learn that its maximum light transmission peaked at about 91 per cent in the optimal, green-yellow visual range, according to spectrophotometric measurements conducted by Allbinos on a slightly earlier, 1985 model.

Short on eye relief though, but amazing if you manage to hook your eyes up with those ocular field lenses!

All in all, a very nicely operating classic compact porro, and quite collectible even in the 21st century. It certainly puts a smile on my face every time I use it.

The next model is a later dated instrument from the UK-founded Opticron optics firm. Called the Dioptron 8 x 32, it was fashioned in Japan and dates to the mid-1990s. Thus, it represents the next step in the intelligent design of the compact porro prism binocular. I picked this model up for just £50 plus shipping.

The Japanese-made(c.1995) Opticron Dioptron 8 x 32, together with its bonded leather carry case.

Though of slightly lower profile than the Zeiss Jenoptem, the Dioptron weighs roughly the same as its German counterpart, so its one chunky little glass.

Note the nice multi-coatings on the ocular lenses.

The Japanese origin of the Dioptron is betrayed by the stamp on the front of the binocular, which unscrews to allow it to be mated to a tripod:

Made in Japan.

The instrument also arrived well collimated, which flies in the face of those who insist that porro prism designs are much more susceptible to misalignment than their roof prism counterparts. If you mistreat any binocular, you’re in for trouble. But treat them well and they will serve you for a lifetime.

The objectives show a very prominent blue anti-reflection coating, unlike the prominent purple hue on the Jenoptem objectives.

The anti-reflection coatings on the mid 1990s Opticron Dioptron 8 x 32.

The big difference between the models is the focus wheel. In a departure to classic German compact binoculars, the Dioptron focus wheel is much larger and easier to access than that of the Jenoptem. Even after all these years, it works like a dream. Very high quality indeed!

Note the much larger and easier to access focus wheel on the Opticron Dioptron.

One slightly niggly thing about both instruments is the easily moved nature of the dioptre rings. Taking them in and out of their cases generally bumps the dioptre off its optimal setting, and even when holding them up to your eyes is quite enough contact to make them wander. Thankfully, this problem is all but fixed in later models.

Overall, the Dioptron is extremely easy to use, even though it shares the same poor eye relief with the Zeiss Jenoptem. Optically, it offers up a very good image, slightly better in fact than its German counterpart, but what genuinely surprised me was the strong colour cast of the images it serves up. It was considerably yellower than the older Zeiss glass. I would describe it as very ‘warm.’ And going from 8.4 angular degrees in the Zeiss down to 8.25 degrees in the Dioptron is quite noticeable to my eye. The Opticron does have noticeably better control of glare however, which renders its images that little bit more contrasted than the Jenoptem.

Both the Carl Zeiss Jenoptem and the Opticron Dioptron classics can be enjoyed entirely on their own terms. I’ve taken both instruments out on long walks in the countryside and have thoroughly enjoyed the lovely large fields of view and very large sweet spots, as well as the characteristic 3D pop they both command. The worst of the glare is seen when these instruments are pointed near bright light sources, but a lot of this can be removed simply by shading the objectives with your hands.

Both instruments helped me to finally make the transition to using high quality porros in preference to roof prism models when using compact binoculars in the field. The transition feels entirely natural for me.

After all, I’m a dyed-in-the-wool classicist don’t you know!

Thanks for reading!

 

De Fideli.

2 thoughts on “A Closer Look at Two Compact Porro Classics.

  1. Hello Neil
    Enjoy reading your blog

    The accidental diopter movement can be easily overcome with a small 1/4″ band cut from an old road bicycle inner tube and stretched carefully over the ocular, positioned at the bottom where the ocular assembly meets the bridge (where the diopter referencemarks are). If it’s a good tight fit it will hold the eyepiece and stop it turning in use or when removing/replacing the binocular from/in the case. Although it covers the diopter markings it will stop movement and is cheap and easily removed.

    Cheers

  2. Hello Ian,

    Thanks for your message!

    That’s a brilliant solution I had not thought of!

    Thanks for passing on the tip. I have a few rubber bands I will try out to stabilise these dioptre rings.

    Thanks a million.

    Neil.

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