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Showing posts with label Aspherical. Show all posts
Showing posts with label Aspherical. Show all posts


Voigtlander Super Wide-Heliar Aspherical II 15mm f/4.5 Lens

Amateur PhotographyThe Voigtlander Super Wide-Heliar Aspherical III 15mm f/4.5 is the third generation update to a lens that has been popular with Leica M mount shooters since Cosina licensed the Voigtlander brand name in 1999.  Made in Japan, the new lens has the same optical design as its predecessors but includes the rangefinder coupling, 52mm filter thread and modern Leica M mount (instead of the original screw mount) introduced in the 2009 re-design.

 Subjective assessment of images captured with the Voigtlander Super Wide-Heliar 15mm lens on the Sony α7 II camera showed them to appear somewhat flatter and not quite as sharp as images from the 16-35mm lens we used for our original camera tests. This is probably a result of how the light reaches the sensor (see above) and how it is handled (or not) by the image processor. The phenomenon has good and bad aspects.

Flatter images are more likely to record the widest possible tonal gamut, whereas very contrasty images often compress highlight and/or shadow detail and either or both can be lost. Flatter images also provide more scope for post-capture processing and it is easy to boost contrast and saturation to whatever extend the photographer desires.

But, the flatter the image, the less easy it is to discern edges precisely. This can make manual focusing difficult since if you can't resolve edges, you can't see whether the lens is precisely focused.

This lack of clarity may have influenced our test results, despite the fact that we conducted four sets of tests, re-focusing after each. The results presented here are an average the figures obtained in the best two test runs.

Throughout our tests the lens failed to reach the resolutions expected from the α7 II's sensor, although the highest resolutions came acceptably close. Edge and corner softening at wide apertures was both observed and confirmed by our Imatest tests in test shots taken without in-camera correction, as shown in the graph of the results, below.

Lateral chromatic aberration figures were mostly within the low range, edging into the moderate range at the widest aperture. Some purple fringing was found in test shots, particularly in outdoor subjects where contrast was high. In the graph below, the red line separates negligible from low CA, while the green line marks the lower boundary of moderate CA.

Vignetting was noticeable in raw files taken with the widest aperture settings, although it was less visible in JPEG shots taken with the camera's built-in corrections engaged.  Interestingly, we found few instances of the colour shifts reported in reviews of previous versions of the lens.

Rectilinear distortion was remarkably low for a lens of this type. We found no obvious distortion in shots taken with the camera back parallel to the subject. However, even a tiny tilt caused vertical lines to begin converging. (This is often a 'wanted' result of using very wide angle lenses and some interesting images can be obtained by exploiting it.)

The lens also appeared well able to deal with strong backlighting and we had no instances of flare in any test shots. Bokeh is never a consideration in lenses with such a wide depth of field, which aren't ideal for close-ups or portraiture – unless you want to capitalise on the inherent characteristics of the lens.

 Although not a perfect match for the digital sensor on the Sony α7 II camera, the review lens was able to produce some interesting images. The combination of the small, pan-focal lens and compact full-frame camera body was great for street photography. It was possible to shoot subjects close-up without them being aware of the camera, using just the monitor screen to compose shots.

The wide depth of field at smaller aperture settings allows photographers to set the aperture and focus rings and simply aim and shoot. The most practical aperture settings are between f/5.6 and f/11, after which diffraction starts to reduce image sharpness. The virtual lack of rectilinear distortion makes this lens suitable for some types of architectural photography.

If you can handle the inherent limitations of the lens design, it's well worth a look. It's considerably smaller and lighter (and a bit cheaper) than Sony's  nearest equivalent, the Vario-Tessar T* FE 16-35mm f/4 ZA OSS, which we reviewed recently. It also covers a wider angle of view than Sony's SEL28F20 FE 28mm f/2 lens plus the  dedicated fish-eye converter lens (which also covers the 16mm equivalent angle of view).The only way to buy this lens in Australia is from the local distributor. Equivalent Voigtlander adapters for Canon and Nikon full frame DSLRs are not listed on the Mainline Photographics website currently. (Older versions of the lens, both new and secondhand, can be found online.)