Article Index

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.