Wednesday, January 28, 2015

Sony SEL 50mm f/1.8 OSS Review

Sony SEL 50mm f/1.8 OSS Review

It's because of a historic market quirk that 50mm lenses are still sold as "low-light" options for APS-C cameras. Before the rise of mirrorless cameras, 50mm lenses were inexpensive hold-overs from the film era for DSLR's. Because Canon and Nikon were slow to offer meaningful crop-frame prime lens options for their respective systems, the first lens that many people supplemented their kit lens was with a "nifty-fifty". This doesn't truly apply to the mirrorless era, as most mirrorless cameras either have stabilization in the body or have stabilized lens options. The Sony E-Mount cameras are such a case; the kit 16-50mm f/3.5-5.6 OSS PZ lens has a very pedestrian aperture range, but it does have image stabilization. If you assume that the image stabilization system gives you three stops of hand-holding advantage, then the kit zoom is roughly as good as a 50mm f/1.8 in low light... for non-moving subjects anyway.

However, 50mm on APS-C is the equivalent of 75mm on full-frame, so it's not a good focal length for general purpose use. It is good for portraiture (though some will argue that even that is too short), and to that extent, the Sony E 50mm f/1.8 OSS fits the bill.

Design and Construction


Like all Sony lenses, the 50mm f/1.8 OSS is light weight and minimalist in design. You get one drive-by-wire focusing ring and that's it; no distance scale. The ALC-SH116 lens hood is included, but if you get the silver version of this lens, the lens hood will still be flat black and will look out of place.

Sony E 50mm f/1.8 OSS on NEX-6

Focusing and Image Stabilization


Focus performance will vary according to which body you are using this lens on. If you are using it with a pre-A5100/A6000 body without on-sensor image stabilization, focusing speed will be adequate; it will be reasonably quick on the newer bodies. However, since this isn't a general-purpose or action-oriented lens, fast focusing is not the priority.

For video, you always get the best results with manual focus. This is true even for the A6000, in spite of its phase detection capabilities.On that camera focus is quick and the camera will track moving objects, but the performance is no where near as reliable as during stills picture-taking. In the sample below, note where/how the camera losses focus lock:



Three-stops advantage is about the most that you can practically expect from Sony's OSS image stabilization system, though you will be safer to plan your shots assuming an average of two-stops advantage. If you are using this lens as a portrait lens, you shouldn't have any trouble hand-holding it below f/2.8 in reasonable light.

Image Quality


Overall Image Quality


This lens is in keeping with how most consumer-grade mirrorless lenses are built; the results are visually pleasing but not technically perfect. There is a lot of electronic correction going on with the out of camera JPEG's; if you shoot RAW you will see a moderately heavy amount of vignetting below f/2, which nonetheless shows up on out-of-camera JPEG's (see below). Center resolution is good but corner resolution isn't much to rave about. To get a good across-the-frame rendition, the lens needs to be stopped-down to f/2.8 or higher. Lateral chromatic aberration is well controlled, but like my fast-aperture primes, there is some longitudinal aberration to be seen with the lens held wide-open. Overall, the optical quality of this lens is competent but not perfect. It will do just fine for portrait shooting, and for the price, there really isn't anything to complain about.

Bokeh




Because lens optical performance is a complex topic, the objective description of such is beyond the scope of this blog. Though there are many aspects to quantify (resolving power, field curvature, distortion, aberrations, etc.), a general sense of a lens’ character can be determined without resorting to lab testing. The following is one aspect; bokeh and apparent background blur with the subject at short distances. The figurine is 3 inches high set at a distance of approximately three feet.

Bokeh is generally smooth, with minor amounts of fringing at wider apertures. The background rendition is smooth and without too much in the way of "business".  There is visible distortion of highlights at f/1.8, but they return to a round shape around f/2.8.

f/1.8
f/2.8
f/4
f/5.6
f/8

Conclusion




At just under $300 USD, the SEL 50mm f/1.8 OSS is neither un-affordable, nor is it a bargain. The price is not unreasonable considering that image-stabilization is included, but you get can better optical quality on a Canon or Nikon system with their respective 50mm f/1.8 lenses. For most people, this lens won't be on the top of their priority list. If it isn't available as a bundle, the SEL 55-210mm f/4.5-6.3 OSS is often the first lens that E-Mount users add to their system. For a general faster aperture prime, the SEL 35mm f/1.8 OSS is a better "walk-around" choice. However, for quality portrait work, there this is Sony's only crop-frame option, and it does well for its intended purpose.



With thanks to Broadway Camera

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