DOCTER® 7×40 B/GA

The binoculars that are the subject of this review have a long history behind them, a history that recalls, first and foremost, the well-known Zeiss brand. Compared to the historic Zeiss Jena EDF 7×40 NVA series, in fact, little has changed. The newer DOCTER® 7×40 B/GA no longer makes use of the removable illuminated reticle operating with radioactive tritium, the optics composed of radiation-resistant SF3 glass and the resulting yellowish tint. This is the new civil version of a classic that the engineers have tried to reproduce while keeping its most important characteristics intact.

As German manufacturers are wont to claim, these are “expedition” binoculars suitable for hiking among glaciers or in the hottest deserts on the planet. I will now explain whether the promises have been fulfilled.

Construction and Mechanics

The hull of the DOCTER® 7×40 B/GA is composed of magnesium and aluminium, and its structure is very robust. The steel that made up the hull of the old NVA is therefore not present. As a military-derived binocular designed to withstand the most adverse weather conditions, great importance was attached to the mechanical components.
The easily removable rubber is also very robust, while its remarkable waterproofing enables it to withstand extreme temperatures and accidental immersion in water. The weight I measured, using the electronic scale, with the caps and strap, is lower than stated. It stands at 970 grams. Without caps and strap, the weight is around 860 grams. A very good value, in fact the DOCTER ® 7×40 B/GA is a very compact and light binocular.

The “command bridge” is spartan and intuitive: a single focus on each eyepiece, excellent rubber bellows light shields with a small hole to prevent fogging of the first lens during winter use.

There are also three simple reference marks for checking one's interpupillary distance. More importance has been given to the diopter adjustment rings (-+7). Looking at it, you can see that the DOCTER® 7×40 B/GA is not a “fashionable” binocular. Its design is more reliable than glamorous and aims at essentiality, I would dare say that this is not a pair of binoculars for panto enthusiasts but a classic working instrument built to withstand, better than its owner, the inevitable passage of time..Tempus fugit!

 

The inside of the optical hull is optimised with various diaphragms, the internal opacification also seemed very effective to me. Docter also confirmed to me that the binoculars are filled with nitrogen as well as being studded with countless o-rings.

Focusing system.

The focusing system is single on each eyepiece. As is well known, although there are excellent internal focusing systems with a central rotor these days, maximum robustness and waterproofness is achieved by using a separate focusing on each eyepiece. After all, in extreme use it is always possible to break an eyepiece. It would therefore be feasible to use the instrument in such severe situations thanks to the eyepiece remaining intact from the impact.

Adjustment is smooth and there is no play or jamming due to the simplicity of the system. What is less complex is usually also more robust. The minimum focus is five metres, while the full depth of field can be appreciated from about 50 metres (this factor, in addition to the square of the magnification (7×7) also depends on one's visual accommodation)

In fact, in panoramic-terrestrial use one often forgets which was the last time one had to focus. The eyepiece travel is obviously minimal, just over half a turn of the knob. It takes less than half that travel to go from minimum focusing distance to infinity.

 

Lenses and treatment

 

Those who buy the DOCTER® 7×40 B/GA do so primarily for its excellent construction, so much so that it is “wasted” in most amateur use. However, its optical performance, although not aspiring to excellence, is also more than good.

The forerunner of this series (Zeiss Jena EDF 7×40 NVA) made use of a special radiation-resistant FLINT glass, the SF3R, which was used for the first eyepiece lens and the negative lens in the optical system. These elements were also the main contributors to the intense yellow hue of the old Zeiss Jena. Compared to other glasses, the SF3R did not blacken when subjected to radiation.

The newer DOCTER ® 7×40 B/GA, on the other hand, has a better corrected, but not yet neutral, hue. In fact, there is a noticeable yellow hue, which I personally find pleasant and which allows you to penetrate more into the landscape in the presence of mist or to limit the glare when observing a snowy landscape. These binoculars seemed to me to be able to absorb much of the UV rays during the sunniest days. This could be due both to the treatment but also to the composition and choice of glass.

There is no organic treatment on the lenses. In fact, the designers preferred to apply an inorganic multi-layer treatment that is more resistant to dust, micro-scratches and cleaning in the long run.

 

Eyepieces

The optical scheme of these binoculars is called (telephoto lens design) in fact the optical group, as visible in the photo is quite complex. The eyepieces consist of no less than five lenses.

However, its true field of view is not very wide: 7.5° (52° apparent field) It is therefore not a wide-angle binocular. The pupillary extraction is very good at 20mm. In addition, thanks to the bellows hoods you can adapt the binoculars to the shape of your face or the glasses you use.

The interpupillary distance provided is between 54mm and 75mm. At minimum adjustment, the distance between the eyepieces is 7mm. Again, thanks to the flexibility of the lens hoods, a fair degree of comfort can be achieved. To reach infinity, the eyepieces must be rotated clockwise.

Prisms

Note the robust guardrain that protects the eyepieces.

 

The heart of these binoculars is a Schmidt Pechan type roof prism system (6 reflections and 4 glass air passages). This optical scheme consists of a 45° prism and a classic Schmidt prism. The Schmidt Pechan system is used for its extreme compactness, but requires a layer of aluminisation or silvering that is applied to the surface of the prism. This layer absorbs a small percentage of light which generates a partial reflection, which is of course less than the so-called “total reflection” that takes place inside the Schmidt Pechan prisms, which is close to the 90%.
Prisms aside, the DOCTER® 7×40 B/GA has a feature that few enthusiasts are aware of: these binoculars have no phase treatment.

I would like to remind readers that this treatment consists of a special coating, through the deposition of dielectric layers on the surfaces of the prism. Thanks to this system, it is possible to compensate for the phase shift of the light waves coming from the two cross reflections on the aforementioned surfaces. For the same optical quality and optical hull, binoculars without phase treatment have a lower sharpness and resolving power than those with it. Obviously, well-designed binoculars that make use of good prisms could provide better performance than a cheap roof binocular with phase treatment.

Susan Adam of Docter-Germany also confirmed to me that the German engineers are thinking about a possible phase treatment, but this would significantly raise the price of a product whose main characteristic is also its remarkable price-performance ratio. Moreover, wishing to remain somewhat traditionalist, they have, in part, decided to “respect” the initial design, which at the time of its appearance did not envisage phase treatment as it was still unknown.

In fact, in practical use, the absence of phase treatment is hardly noticeable, although it does not achieve first-class definition. As mentioned, the optical performance is very good and seemed to satisfy even the “most refined palates”.

Field curvature

The DOCTER® 7×40 B/GA provides a perfect field of view up to 80% of the field of view, after which there is a loss of definition or blurring due mainly to the curvature of the field. However, thanks to its complex optical scheme, which should perhaps also contain a lens to level the field, blurring is minimal and allows the framed scene to be easily perceived. In daytime observation, in fact, the images rendered are pleasant and low-fatigue.

 

Other aberrations

To check astigmatism, I mounted the binoculars on a Berlebach mount to test them on late autumn constellations.

In this circumstance the binoculars show very spot-like 2nd magnitude star images up to about 80% of the field. Only very slight astigmatism is present at the edges: I would say that this is one of the best performances I have encountered in binoculars with roof prisms in this price range.

Date of astronomical test: 12 November 2012
Model
Nobilem BGA 7×40
Highest nesting field with 3rd magn.point stars
CM80%

Star pointiness in the CM 
9/10

Other aberrations
20% mild astigmatism

Chromatic aberration

Chromatic aberration is definitely well corrected, partly due to the slight warm tone that certainly helps a little.

Even during critical lighting conditions one notices a very good containment of this aberration. Some chromaticism towards the edges of the field is more visible.

Angular distortion

The 3-5% from about the 80% of the field.

Prism Vignetting

In the test specimen I did not notice any vignetting. The exit pupil was perfectly spherical and illuminated.

Practical use

Although Docter did not wish to specifically state the performance of this instrument, various authors have repeatedly cited the performance of its precursors, which were subjected to extremely harsh tests. It could withstand and function for at least an hour after being frozen down to -60° or after being heated up to +50°. Furthermore, its maximum storage temperature could even reach 80° after which the lubricants used could begin to lose their functionality.

That is why, after getting the agreement from Docter Germany, I checked its robustness through various tests.
1) Multiple dives in streams in my area to depths of over 40-50cm.
2) Filling the eyepiece hoods with water.
3) Various falls from a height of 80-90cm, on various types of terrain
4) Compression with a rock weighing 5kg for the duration of one night.
5) To finish perhaps the worst of the trials: I placed the binoculars, wet, inside the freezer for a couple of hours.

In all the situations, just mentioned, the binoculars suffered no damage, apart from a few scratches to the rubberizing, which deserves a little description. Thanks to its quick release, the binoculars can be cleaned very easily after falling in the mud or being subjected to heavy rain or immersion in water.

It is also possible to very quickly remove the rubberized part that covers the lenses. This facilitates the removal of the inevitable drops of water that can seep under the rubber protection. Nothing, I repeat nothing, has crept inside the lenses or the optical hull.

When walking through the woods in my valley with the DOCTER® 7×40 B/GA, one can concentrate very much on the purpose of the excursion, which is to observe nature and animals without regard for the rest. Often, when I use emblazoned optics, especially on trials, I am always afraid that they will fall off, get scratched or damaged. The B/GA 740, on the other hand, is a real tank and will happily take on any kind of adventure. After all, it has been my favourite “rain and mud” binoculars.

If I may exemplify, I would say that it is like tackling a dirt road with a rugged Defender rather than a shiny SUV. The Docter likes to be treated badly and the user is gratified by its robustness.

Luca Mazzoleni, a well-known Italian restorer of binoculars and a great lover of optics, has often described to me his youthful adventures in the mountains, and almost all of them were tackled with these binoculars, which for years were propped up on the sharpest spikes in the Piedmont mountains, sunk in fresh snow, rolled down accidentally in stony mule tracks or used unscrupulously in the pouring rain

Well, if you think you should do that too, this is the binoculars for you

 

The ergonomics are good, I appreciated its great depth of field, which with visual accommodation goes beyond the minimum square of the magnification. Irreplaceable, when used for many hours the eyepieces, with their bellows, pleasant warm tone that makes the landscape more vivid and allows comfortable use, during the sunniest days even at the seaside, lake or in the presence of snow. These are the classic binoculars for the extreme hiker.

Strengths and weaknesses

The merits are many; its robustness, compactness, ergonomics, depth of field, brightness and excellent pupil extraction.

 

Defects? Under certain lighting conditions I noticed a little scattered light at the edges of the image, perhaps attributable to the absence of phase treatment. Actually, if I had not been aware of this issue and had not ascertained the absence of the treatment during the test, I might not have noticed it. In fact, in most cases the diffused light is well corrected. As far as definition is concerned, we are obviously not at the level of the best optics on the market, but those who choose the DOCTER® 7×40 B/GA also look out for other features.

 

Therefore, as anticipated, I fear that if Docter's optical engineers decide to equip these binoculars with phase treatment, competitors might start to worry even more.

Accessories

In dotazione è presente soltanto una cinghia, insieme ai tappi di protezione per le ottiche ed un panno per la pulizia.

In summary.

Reputo il DOCTER ® 7×40 B/GA un binocolo ideale per chi ha bisogno di un strumento di lavoro molto resistente o di un valido compagno di avventure. Qualora non si fosse presi dalla smania di ulteriori acquisti sarebbe in grado di accompagnare il fortunato acquirente per tutta la sua vita e di allietare figli e nipoti.
Acknowledgements

Ringrazio la dott.ssa Susan Adam per avere messo a disposizione l’esemplare oggetto di questo test.
Disclaimer. Questa recensione è stata pubblicata nel mese di Novembre 2012. Si specifica che le impressioni d’uso sono totalmente personali e date dai tester di Binomania in completa libertà, senza vincolo e rapporto commerciale alcuno e sulla base di esperienza comprovata nell’utilizzo di tali strumenti ottici. Per eventuali informazioni, aggiornamenti e/o variazioni sui prezzi, sulle caratteristiche dello strumento, su i punti vendita autorizzati o altre informazioni in genere, si prega di contattare direttamente l’Adinolfi S.r.l. cliccando sull’immagine qui di seguito.

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