Anyone know DXO's sigma sensor test?

Started Apr 27, 2012 | Discussions thread
DMillier
Forum ProPosts: 16,971
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Re: Lots of theories - all wrong?
In reply to DMillier, Apr 30, 2012

Answer my own question.

Short answer:

Resolution - the SD1 has high rez but is still beaten here slightly by the NEX 7.

Dynamic image - at the highest quality level SD1 one stop worse than NEX 7 and 2 stop worse than K5/D7000. This is not bad actually, as the EXMOR sensors have raised the bar. This means SD1 is about on a par with older sensor designs like Canons (and they were not considered bad at all until the EXMOR appeared).

SD1 imatest results in detail:

colour

Muted color with slightly below average hue accuracy. Hue error increases and saturation falls rapidly at ISOs above 800. we noticed saturation falls off rather rapidly at ISOs above 800 to the point where colors have lost almost 50% saturation at ISO 6,400. It's not unusual to see a drop in saturation at higher ISOs, but we're not used to seeing it as dramatic as this.

Outdoors, daylight

Good exposure but muted, slightly warm color outdoors. The Sigma SD1 struggled a bit under harsh sunlight, yielding muted colors as well as a lot of clipped highlights, though exposure accuracy was better than average. Default exposure was a little hot, clipping some highlights in the white building, though shadow detail was quite good if a touch noisy.

Resolution

Very high resolution, 2,100 lines of strong detail from JPEGs, about the same from converted RAW files.

c/f to NEX 7: Resolution

Very high resolution, about 2,200 to 2,300 lines of strong detail from JPEGs, up to 2,400 from RAW files.

Sharpness & Detail

Excellent sharpness straight from the camera, with very minor edge-enhancement on high-contrast subjects. Moderate noise suppression artifacts at base ISO.

Sharpness. The Sigma SD1 produced images with excellent sharpness and very good detail, doing much better than a typical 16-megapixel Bayer sensor would do at base ISO.

Detail. The crop above right shows some detail loss due to noise suppression, as darker areas and areas of low contrast in the model's hair show some smudging and loss of definition.

ISO & Noise Performance

Very good handling of noise vs detail at low to moderate ISOs, but image quality quickly deteriorates at higher ISOs.

Images were reasonably clean at ISO 100 through 400, with just a touch of luminance and chrominance noise visible in the shadows. As mentioned, though, colors are already quite muted at base ISO. Chrominance noise becomes noticeably stronger at ISO 800 in the form of large pink and green blotches, though luminance noise was still pretty good.

Extremes: Sunlit, dynamic range and low light tests~

Very high resolution but with poor highlight preservation. Fair low-light performance, capable of capturing bright images in near darkness at low ISOs, though autofocus struggled and higher ISOs were very noisy.

dynamic range

The Sigma SD1's RAW file scored essentially the same in total dynamic range compared to the JPEG (9.78 vs 9.76 f-stops) however the score at the highest quality level increased about 1.8 f-stops from 6.1 to 7.92 f-stops. This is still a below average score, though, and it's worth noting here is that Photo Pro's default noise reduction settings reduced overall noise relative to the levels in the in-camera JPEG (compare the noise plots in the graphs), which tends to boost the dynamic range numbers for the High Quality threshold.

c/f to NEX 7 etc: the score at the highest quality level increased from 7.52 to 9.38 f-stops, which is almost a two f-stop improvement, while total dynamic range increased just over one f-stop, to 13 from 11.9. The High Quality results are very good, though not quite as good as the best APS-C sensors we've tested, hampered somewhat by slightly higher noise levels from the NEX-7's denser sensor. (The Nikon D7000 for example scored 10.1 f-stops at the highest quality level, while the Pentax K-5 scored 10.2 f-stops.)

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