Introduction

Pentacon, an East German camera and lens manufacturer of the Soviet-era, was formed in 1959 through a merger of several East German camera manufacturers. The company initially carried a different name, but in 1968 was renamed to VEB Pentacon after another famed East German optics manufacturer, Meyer-Optik Görlitz, was merged into the company. Meyer was the original developer of a number of very popular at that time lenses, with most lenses carrying design names like Orestogon, Lydith, Oreston, Primotar and Trioplan after the optical designs used in the lenses. All these lenses were renamed to Pentacon and design naming was dropped. So Pentacon 50mm f/1.8 is effectively a Meyer Oreston 50mm f/1.8 and Pentacon 300mm f/4 is actually Meyer Orestegor 300mm f/4 and so on... To make things even more confusing, Carl Zeiss Jena carried a couple of old Meyer designs and exported them to Western countries under 'aus Jena' brand. Particularly, Meyer Orestogon 29mm f/2.8 (also named Pentacon 29mm f/2.8) was quite common in Western Europe in 80s and 90s and can be often found these days on eBay. You might want to check the Historabilia section if you are interested in the fascinating history of East German camera manufacturers.

With Pentacon 50mm f/1.8 effectively deriving from Meyer Oreston 50mm f/1.8 design, you can encounter a number of variation of this lens. including the original, what is called 'zebra' Meyer, as well as 'auto' and 'electric' versions of Pentacon. To the best of my knowledge, the only differences between one version to the other are either cosmetic or mechanical, i.e. automatic diaphragm control vs manual, and there are no optical changes in the design except for some improvements in coating. Both Pentacon 50mm f/1.8 as well as its predecessor Meyer Oreston 50mm f/1.8 are quite common on used markets (in all possible variations of the lens). Quality copies are quite inexpensive, with Pentacon 50mm f/1.8 going for ~US$50 and Meyer 50mm f/1.8 going for ~US$70 on eBay.

The optical construction of the lens consists of 6 elements in 4 groups. The build quality of the lens is pretty good with metal barrel and rubberized focusing and aperture rings. The lens is quite compact and light, measures 48 x 51mm (1.88 x 2in) and weighs 250g (7.76oz), although the barrel extends slightly during docusing. The minimum focusing distance is only 33cm (12.9in) and the minimum aperture is f/16. The lens accepts 49mm screw-in type filters.

 

Both Meyer as well as Pentacon variations of this lens were available in M42 as well as Praktica B mounts. The M42 mount lenses are generally easily adaptable to a number of cameras, including Canon EF/EF-S and Four Thirds systems. Since original Pentacon 50mm f/1.8 was designed for 35mm cameras, when used on APS-C bodies with 1.6x crop factor, the lens will have a field of view similar to that of an 80mm prime on full frame body, and when used on Four Thirds cameras, it will have field of view of a 100mm prime.


Summary
Lens Composition 6 elements in 4 groups
Angular Field 45 degrees
Minimum Focus 33cm/1.08ft
Focusing Action MF
f-stop Scale f/1.8-f/16, manual
Filter Size 49mm
Lens Hood N/A
Weight 250g/8.81oz
Dimensions 51x48mm/2x1.88"
Lens Case N/A



Field Tests

50mm focal length is probably one of the most popular among photographers. Demand stimulates supply so naturally there are quite a bit of different options when it comes down to 50mm primes, with each of the modern camera/lens manufacturing offering one, sometimes even two or three different 50mm models. So why review an old, discontinued long time ago lens? What can such an old lens do what a modern lens from Canon or Nikon cannot do? Call it a nostalgia, or for more practical reasons call is a search for a cheaper quality lens. Either way, here we are, with Pentacon 50mm f/1.8 mounted on Canon 5D. Like most M42 mount lenses, the 50mm Pentacon mounts on both full frame and APS-C Canon cameras without any problems, but you would end up operating the lens in a fully manual mode, including manual focusing as well as manual aperture setting. Not a big deal if you used manual lenses in the past, but if you are switching from AF-everything camera, then you can quickly get annoyed by a few quirks like stop down metering and lack of shutter priority mode.

Once mounted on a camera, Pentacon 50mm f/1.8 feels pretty much like any other 50mm prime, however, unlike many other 50mm lenses, this one has an extremely long focusing drive. Some may call it precise focusing, I just call it long - almost 360 degrees of rotation to go from the infinity to the closeup. Some dedicated macros don't have such a long drive. More accurate focusing as mentioned is one major benefit here - the focusing drive is longer at closeup ranges, ~40 degrees to go from 33cm to 34cm, enough to give you full control over where to focus and how to position that pretty thin DOF that the lens is capable of delivering. More about this in a bit. However, the disadvantage of a such long focusing drive is that it takes quite a bit of time to rotate that darn ring to focus! QUick focusing on manual lens is hard enough, but on Pentacon 50mm it would be practically impossible, unless you preset your lens, using an engraved on the side of the barrel DOF scale.

Let's talk about DOF now. A shallow DOF and bokeh handling are often quoted as main reasons why photographers are eager to try out such old lenses as Pentacon 50mm f/1.8. Naturally, the shallower is your DOF, the better isolation you would get between the subject in focus and fore/back-ground. Combine that with rich, saturated colors, good resolution and good contrast and you have a winner on your hands. The shot below simulates the DOF you can achieve with this lens at its minimum focusing distance and wide open aperture.

 

dof-pentacon-50mm-f18m42-iso400-s640-f18-50mm

ISO 400, 1/640, f/1.8, 50mm (Canon 5D)

 

Well, 'this seems like a pretty thin DOF, but nothing unusual' you might say. Right... There are obviously other lenses that are capable of producing as thin or maybe even thinner DOF, but take a look at the next couple of shots done at the small beach-head off the Marine Dr in San Francisco. The completely blurred shape in the photograph on the left is the Golden Gate Bridge. Both shots were made at the minimum focusing distance. Naturally, since the bridge is much farther then the subject in focus, even f/16, shown in the shot on the right, would blur the background to some extent.

 

sfdof1-pentacon-50mm-f18m42-iso100-s1600-f18-50mm

ISO 100, 1/1600, f/1.8, 50mm (Canon 5D)

sfdof2-pentacon-50mm-f18m42-iso100-s30-f16-50mm

ISO 100, 1/30, f/16, 50mm (Canon 5D)

 

Ok, so by now we can safely say that the lens can indeed give us pretty good separation. You can however notice, from another sample shot below, that at wide open aperture, the lens does produce pretty harsh highlighting around edges in OOF highlights. There is also a little bit of double-edging around the out of focus objects, which while not too pronounced does create a minor sense of distraction. More noticeable however is  the lack of definition, resolution that is. Now, at close focusing distances and wide open aperture, image borders are blurred so there is no point in discussing the resolution. But notice that the images taken at close focusing distances are noticeably softer then images  taken at infinity or close to infinity (just compare a couple of shots from the sample image gallery with the DOF shots above). It does seem that the lens is optimized for infinity, doesn't it? Moreover, even at infinity, image borders are noticeably soft at wide apertures - by f/4 most lenses show pretty good resolving capabilities both in the center as well as around borders, but with Pentacon 50mm f/1.8 you need to stop down to about f/8 to get a more or less uniform results across the frame. While not very desirable, you might be surprised to learn that in 60s and 70s some lens designs were developed specifically with such behavior in mind. Several famous lens designs from Leica, Zeiss and  Angenieux produced noticeably soft images at wide apertures. The main reason for that was to create rendering that softens skin tones and even adds a little bit of glow, thus creating even smoother transitions in midtones without sacrificing the overall image contrast. Now, I don't really know whether the designers of the 50mm Pentacon purposefully designed a lens that is soft around borders, or this is just a plain bad design, but the lens is noticeably soft, so you need to take this into account when using the lens and either stop it down to f/8 or f/11 and rely on some post-processing to improve the sharpness (if you want to improve it of course).


ISO 100, 1/500, f/1.8, 50mm (Canon 5D)

 

Try hard enough, and you will see flare in pretty much any lens, and the flare tests here try to stress lenses as much as possible to see where that point of failure is going to be. In many cases this means finding the most extreme situations possible, situations that are not necessarily common in your typical day to day photography. The shots below show such stressfull situation - the sun was peaking from the top of the building on the left side, with the sun rays hitting the front element at about 65 degrees. Naturally you can see flare, glare, desaturation, color streaks and ghosting all together, but again this does not mean that you would always see these results - not unless you ignore the most basic precautions. Hence there is probably no need to panic here.

 

flare1-pentacon-50mm-f18m42-iso100-s2000-f18-50mm

ISO 100, 1/2000, f/1.8, 50mm (Canon 5D)

flare2-pentacon-50mm-f18m42-iso10-s200-f8-50mm

ISO 100, 1/200, f/8, 50mm (Canon 5D)

 

Like most fast lenses, Pentacon 50mm f/1.8 falls prone to some vignetting. At f/1.8 the light falloff is moderate on a full frame camera, but quickly disappears once you stop down to f/2.8 or so. On an APS-C body, vignetting is minimal at f/1.8 and basically non-existent for most practical uses starting with f/2.

 

Vignetting @ 50mm - full frame vs APS-C

 

The final note in the field tests is on color rendering. Color palette produced by the lens seemed a little bit warm, with some excess of yellow. The results looked sort of 'Canon'-ish rather then 'Zeiss'-ish, that is warmer tones which are quite common to Canon lenses as opposed to Zeiss lenses that tend to produce cooler gradations of color, with some excess of blue. Color aberration was pretty minimal throughout the aperture range - you can notice minor signs of longitudinal aberration in the sample shots, but nothing really drastic.

 

ISO 100, 1/6400, f/1.8, 50mm (Canon 5D)

 

 


Lab Tests
Please note that MTF50 results for APS-C and Full-Frame cameras are not cross-comparable despite the same normalized [0:1] range used to report results for both types of cameras.

 

Resolution: Canon APS-C

Pentacon 50mm f/1.8 showed rather mixed behavior on an APS-C camera. Center image resolution was quite good throughout the tested aperture range - image quality at f/1.8 is already good and only gets better as you stop down the aperture towards f/8. However, border image quality suffers quite a bit, particularly at wide apertures. At f/1.8 and f/2 border image quality is simply dismal. Quality starts to improve as you stop the lens further - at f/2.8 image resolution is decent, but still not spectacular. Finally, from f/4 through f/11 border quality reaches pretty solid levels. The overall peak performance is in the f/5.6-f/11 range, where the lens is capable of delivering outstanding 19in and decent 24in prints. Conclusion? Well, we know by now that most fast lenses do not show the sharpest results at wide apertures, it's just a question of how quickly image resolution improves with stopped down apertures. In this particular case, the lens becomes a decent performer starting with f/2.8.

 

MTF50 (Line Width/Inch on the Print) @ 50mm

Normalized raw MTF50 @ 50mm

 

Resolution: Canon FF

Like with an APS-C camera, Pentacon 50mm f/1.8 showcased pretty mixed results on a full frame Canon 5D. Center image performance remained consistently high - there is literally nothing to complain about here. But border image quality suffered quite noticeably. And unlike with an APS-C body, border performance improves slower as you stop down the aperture - by f/2.8 the lens showcased quite good results on an APS-C camera, but on a FF body f/2.8 is just as mediocre as at f/1.8 and f/2. Quality does improve little by little, but does not reach solid levels until f/8, with f/5.6 being sort of a transitioning point. Conclusion? Oh gheez, this is rather disappointing - if you are after sharp performance around corners, then Pentacon 50mm f/1.8 should be your primary choice, particularly on a FF camera.

 

Normalized raw MTF50 @ 50mm

 

Chromatic Aberration: Canon APS-C

Chromatic aberration on an APS-C body was somewhat of a mixed bag. CA was moderate to high with wide open aperture - at f/1.8 CA reached 1px in the center and ~1.5px around borders. This will result in some noticeable color fringing in real life situations. As you stop down the aperture, CA is graudally reduced and by f/5.6 becomes quite manageable, hovering at ~0.4px and ~0.6px in the center and around borders respectively.

Chromatic Aberration: Canon FF

Like with an APS-C body, chromatic aberration on a full frame Canon 5D was somewhat mixed. The good news is that CA in the center is slightly lower then on the APS-C body, reaching 'only' ~0.5px at f/1.8. Border CA however is as high - at f/1.8 it reached ~1.4px, slowly dropping towards ~0.5px by f/8.

 

 

Distortion

Like with most standard primes, distortion was  not much of an issue with Pentacon 50mm f/1.8. The lens showed minimal barrel distortion and at ~0.55% distortion should not pose any problems in real  life situations.

 


Chart Crops: Canon APS-C

Here are 100% crops, taken with an APS-C type Canon Digital Rebel XTi, comparing image borders at f/1.8 and f/8.

 

Chart Crops: Canon FF

Here are 100% crops, taken with a full frame Canon 5D, comparing image borders at f/1.8 and f/8.

 

 

 


Alternatives

There are dozens if not hundreds of 50mm prime lenses out there - you can find lenses with close and not so close minimum focusing distance, tiny lenses and giant lenses, macro and non-macro lenses, you name it. So naturally this list of alternative 50mm primes is just a scratch on the surface. But assuming you're into alternative gear (after all, the last time I checked, there are no M42 mount cameras produced these days), you might want to take a look at Contax branded Carl Zeiss Planar T* 50mm f/1.7 and its slightly faster version Planar T* 50mm f/14. Both offer very good performance, but are somewhat more expensive then Pentacon 50mm f/18 reviewed here. Speaking of Pentacon - if you are into collecting lenses, then the previous version of Pentacon 50mm, manufactured by Mayer Optik is obviously an option, however, considering that there were no optical changes between Pentacon 50mm f/1.8 and Meyer Oreston 50mm f/1.8, then the benefit of going with an older lens is non-existent. Among other worthy alternative lenses, Leica's Summicron-R 50mm f/2 and Summilux-R 50mm f/1.4 should be considered by anyone with enough money to afford them. And obviously if you don't really want to deal with alternative, manual focus lenses, then a 50mm prime from your favorite manufacturer like Nikon or Canon would do the trick for the most part,

 

Recommendation

It is hard to find a reason for why someone should choose Pentacon 50mm f/1.8 over the plethora of modern and not so modern 50mm lenses out there. After all, Pentacon 50mm f/1.8  does not strictly excel in every possible category. The lens is certainly cheap and that might obviously be one of the criteria for your decision. Build quality is decent, handling of various artifacts is also decent, but the overall resolution is pretty dismal, particularly quality around borders. Naturally, this lens is not going to be a primary candidate for mainstream users, so those of you excited by the idea of using an old piece of glass on a modern digital camera, go ahead, play with the lens. Just keep in mind that ultimately, there are better lenses out there and Pentacon 50mm f/1.8 probably outlived itself by a decade or two.