Review: IOR-SA 7x40 vs. Zeiss Jena EDF 7x40 vs. PZO 7x45

by Holger Merlitz

After collapse of the East Block of socialist states, their military optical equipment became available on the surplus markets and is nowadays easily accessible via Internet on Ebay or via professional dealers. It was quickly realized that the quality of binoculars used in the Warsaw Pact was comparable, if not superior, to their counterparts in the NATO. Especially the devices made by Carl Zeiss Jena and employed by the East German NVA immediately gained a high reputation among professional users and collectors as well. I refer to my reviews of the DF 7x40 and the EDF 7x40. But there were other binoculars, too, some of them less known by today and nevertheless of amazing performance.

This review compares the Romanian IOR-SA 7x40 with another version of the East German EDF 7x40 and the Polish PZO 7x45. All three of them are full-fleshed military binoculars with a thick rubber armor and reticle. The oculars are individually focused and sealed so that these glasses are water resistant. As common for Warsaw Pact binoculars, they could be equipped with a detector for active infrared sources. The EDF and PZO contain such a detector, the version of IOR presented here is without.

Fig. 1: The Romanian IOR-SA 7x40

There exists a detailed review of the IOR 7x40 binocular by Scott Powers. According to that, IOR is a Romanian manufacturer, located in Bucharest and making optics since 1930. Apparently, they order their quality glass from the German Schott Glaswerke GmbH. This binocular is used by the Romanian armed forces, but seems to be sold to the Soviet army, too. Its serial number indicates 2000 as year of production. The IOR exhibits some similarity to the East German DF 7x40, but is less bulky and slightly less heavy. In fact it settles very nicely in the hand. This instrument comes with yellow filters which are stored in compartments inside the objective lens covers. Although the eye-relief of 20 mm is generous, a use with spectacles on could proof problematic: The contoured rubber eye cups fold down, but then the eye-glass rests on a metallic ring. The device is nitrogen filled and fully water-proof. I have found dealers selling them new in the US for about $350 (see links below), but none in Germany. On Ebay the IOR 7x40 can be found second hand for 250 Euro in good condition.

Fig. 2: The East German NVA EDF 7x40

Being built as a roof prism binocular, the EDF is amazingly compact and light-weight for its specification and ruggedness. Its telescopic rubber eye-cups fold down and are fully compatible with spectacle use. The serial number starts with 'G', indicating 1987 as year of production. This is the version of EDF with illumination (there was also a version without, see here). It features a lever right to the right hand side ocular to switch on/off the reticle illumination, and the symbol for radioactivity. The light source is a small hollow and transparent capsule, filled with radioactive tritium gas and inner walls coated with a tin sulfide layer. The tritium is decaying, emitting electrons which then excite the tin sulfide to emit photons, which finally illuminate the reticle. The EDF was constructed so that the illumination could be removed or installed during maintenance work, i.e. both versions were interchangeable. When the NVA was absorbed into the West German Bundeswehr, the stock of binoculars was taken over, but the illumination was removed since the tritium source did not adhere to the strict West German environmental protection laws. This binocular is therefore much less frequently found on the surplus market and easily sells for 400 Euro. A civilian version is still produced by Docter Optics (see links below) and sells for 700 Euro.

Fig. 3: The Polish PZO 7x45

There is very little information available about this binocular. According to Seeger ('Military Binoculars and Telescopes for Land, Air and Sea Service'), the manufacturer PZO (Polskie Zaklady Optyczne) is located close to Warsaw and was during German occupation producing optical instruments for the Wehrmacht. The PZO 7x45 is presently employed in the Polish army and may be still in production, (see the link at the bottom of this page), but I could not detect any serial number on this device. On the left hand prism housing there is a lever to swing in/out the infrared detector plate. There exist also versions of the PZO without infrared detector and reticle. The specification 7x45 is unusual - it closes the gap between the low light 7x40 binoculars and the true night glasses with 7x50. This device comes with grey colored ocular filters which are stored inside the ocular cover. The rubber eye cups are contoured and, like with the IOR, fold down to expose a metallic ring which then might scratch eye-glasses. This binocular is occasionally found on Ebay and sells for 200-250 Euro in good condition.

Fig. 4: The IOR 7x40, EDF 7x40 and PZO 7x45

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)
IOR 7x40 8.5 60 20 5.7 1.15
EDF 7x40 7.5 53 20 5.7 0.95
PZO 7x45 7.0 49 23 6.4 1.25

Optical performance

Angle of view: These are low light binoculars and one should not expect excessive wide fields of view. Closest to 'wide angle' comes the IOR with 60 degs. apparent angle, which is sufficient to avoid the tunnel-view of its contenders. In fact, with 53 degs. the EDF does not show much. Even narrower is the view through the PZO: The (roughly) 50 degs. is a typical feature of night glasses, and forms the poor standard for most of the 7x50 binoculars.

Image sharpness: The EDF delivers the most convincing performance. From the center to about 80% (radial) to the edge, stars look point-like, and close to the edge the distortions are low to moderate. Its center sharpness is high as is the IOR's and PZO's. The PZO shows some distortions from about 70% onwards, with still a moderate level of aberrations close to the edge. The IOR is razor sharp within 60% of the field, then, toward the edge, degrading, first slowly and then, close to the edge, more rapidly, were the image quality becomes poor. This is not unusual for a binocular of this angle of field. In fact, the overall image sharpness of the IOR is comparable to the NVA DF 7x40.

Image color: The EDF has got a very strong yellow tint. The origin of this color can be traced down to the negative lens of the objective and the first ocular lens. Both of them are made of SF3R, a special radiation resistant flint glass (here I have to correct my statement made in another review: The origin of the yellow color is, at least in the EDF, a radiation resistant glass). The background information can be found on Albrecht Koehler's page (German language): Some flint glasses have got the property to turn black when exposed to radiation. Fortunately, there exist radiation resistant counterparts with identical principal optical characteristics, but not always with neutral color. In this particular example, extended field tests during the construction of the EDF led to the conclusion that the yellow color had positive side effects: Under hazy conditions, the image contrast was improved, and under very bright light conditions, e.g. a sunny day over snow or at sea, the eye strain was reduced and the hazardous UV contribution of the light was removed. That's exactly the reason why some professional binoculars come with yellow filters to be attached to the oculars. The IOR and PZO provide almost neutral image colors. Only a straight comparison reveals that the IOR has a slight yellowish tint and the PZO's image is slightly brownish. None of these binoculars gives a completely neutral color rendition. It is of relevance that the image brightness of the IOR is superior to the PZO and the EDF. Only close to the edge a loss of brightness (vignetting) is visible in the IOR.

Rectilinear distortion: Most binoculars employ a slight pincushion distortion, which is intentionally installed to provide a smooth panning. Without this distortion, the still image looks perfect, but when panning, the same seems to roll over a convex surface, ("globe effect"), as is the case with the Russian BPO 7x30. The IOR and PZO show a slight pincushion distortion which compensates for this rolling ball and leads to a smooth panning. I have noticed that in case of the EDF the amount of pincushion distortion may be a little too large: It over-corrects, i.e. when panning, the image appears to show a concave curvature so that it seems to scroll over the inner surface of a globe. But the quantity of this effect is not yet on a disturbing level.

Stray light: Under difficult viewing conditions, especially a 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. A suppression of this stray light is mandatory to preserve a maximum contrast under difficult viewing conditions, and here all three binoculars are on a professional level. I was unable to provoke any situation where such effects could significantly affect the image quality. If I had to name the most characteristic optical feature of these East block binoculars, then it is probably the excellent control of stray light. And here one comment seems adequate: These glasses are often smiled at, as being bulky and heavy like a tank. But one has to consider the following: A successful stray light suppression first of all requires one thing - space. The tubes and prism housings have to be properly dimensioned to leave space for internal baffles and other constructions to shield the prisms. Consequently, these instruments are somewhat larger than usual, but they are doing well under conditions where others are badly loosing contrast.

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 secondary 'ghost' images of the light source. The EDF is performing best. There is no ghosting through the left tube, and through the right one, the reflections on the reticle remain on a very low level. Closely behind are the IOR and PZO. The IOR displays a diffuse and very dim ghost image through the left tube, the PZO a small localized and slightly brighter one. Through the right tube, another reflection of low intensity takes place on the reticle in both of the glasses. Altogether the ghost image suppression is well done in all three of the competitors.

Low light performance: Here the IOR presents a most convincing performance. Not only at daylight, also after sunset its image appears to be the brightest one. With decreasing amount of residual light, the PZO is catching up: Once the observer's eye-pupils diameter exceeds 5.7 mm, the PZO can take profit of its superior exit-pupil diameter. However, the low light performance of the PZO could never surpass the IOR's. Obviously, the light-transmission rate must be significantly higher in case of the IOR. The coating of this binocular, made in 2000, must be state of the art. Another factor may be a physiological one: The human's eye is optimized for daylight use. After sunset, the spectrum of the residual light is shifting toward the short wavelength (blue) side. A slight yellow tint as present in the IOR may compensate for this effect, i.e. shifting the image color back to what the eye is optimized for. The EDF, with fully multi-coated optics, is also performing well. At twilight it is on the same level as the PZO, but at very low light it is falling a little behind. Here one has to consider the fact that its strong yellow color is reducing the transmission, more so than the just slight yellow tint of the IOR.

Mechanical construction

There is little left to complain about. All three binoculars are of extremely solid, tank-like construction. They are sealed against water and dust, the rubber armor forms a protection against mechanical impact. Mechanical movements are stiff and smooth. None of the contenders exposes any weak point here. The lubricant has been tested to be operational at low temperatures like -30 degs. Celsius. For spectacle-wearer, the EDF is best suited. Although the eye relief is long enough in case of the IOR and PZO, it is of limited use because when folding down the eye cups a metallic ring is exposed which could do harm to the eye-glasses.


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
IOR 7x40 3 1 2 1.5 3 2.5 2 15
EDF 7x40 2 3 2 3 1 1 2 14
PZO 7x45 1 2 2 1.5 2 2.5 2 13

The 'final score' is the sum of the individual scores and is intended to serve as an orientation only. Generally, it would be an over-simplification of the matter to just look which binocular has got the highest score, because it would obscure the individual features of the devices which could differ quite a lot among each other.

The IOR-SA 7x40 is, though with a small margin, the winner of this competition. It displays the widest and brightest image among the three tested devices. Its low light performance is especially impressive. The fact that the image quality is poor close to the edge appears to be of little relevance. Personally, I prefer a wide field of view with some problems at the edge over a narrow field of view with perfect image. Some comments regarding the East German DF 7x40 are useful: The IOR has got similar features, identical specification and field of view. A difference emerges with the fact that the IOR shows some vignetting, which is not there (or much less so) in the DF. The reason is that the DF employs larger prisms, which enable it to fully illuminate the 60 degs. field of view. On the down side, the DF is more bulky and heavy. Here one has the choice: A bulky device with full illumination, or a more compact one with some vignetting. Apart from that, the IOR has got the advantage because of its state of the art lens-surface coating.

The East German NVA EDF 7x40 is since long known to be an excellent binocular. Its prime advantage is its compact size and low weight. When it comes to performance-per-kg, the EDF is ahead of the competition. Disturbing under most seeing conditions is its yellow color. It should be mentioned that a civilian version of the EDF is still in production by Docter Optics, without infrared detector, reticle illumination and without radiation resistant lenses. These binoculars are supposed to have a neutral color rendition, which I think is an advantage. Please note that such a device would have ended up on top of this competition, since it had gained points in both subjects, color rendition and, likely, also in low light performance, since the coating has certainly improved since 1987. With its excellent ghost image and stray light suppression, the EDF is still a good choice for professional applications under any weather conditions.

The Polish PZO 7x45 is hardly known so far. In contrast to other binoculars made in the Warsaw Pact states, this one comes without the characteristic yellow tint, but with its brownish image its also not completely neutral in color. Similar to the competitors, its ghost image and stray light suppression is on top level. A disadvantage is the narrow field of view. Also, the PZO can't take full advantage of its superior objective lens size: Surprisingly, it is beaten by the IOR in their low light performance. Unfortunately I have no clue about the year of production of this item. It appears that the transmission rate is not state of the art. Apparently, this binocular is still in production, and the current version might be delivered with an improved coating.


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.


Ketmer Optics, selling the IOR 7x40

The IOR 7x40 on Fan Tao's page. This is the version of the early 1990's

Docter Optics, producing the civilian version of the EDF 7x40

The LP 7x45Z, the current version of the PZO

Back Home

Last updated: 2004