For bokeh (out-of-focus blur rendering) tests, I usually like to have a second lens for comparison. However, I currently lack another 40mm equivalent lens to compare with the DP2 lens, so I'll just provide some bokeh samples to give an idea of how the DP2 lens renders out-of-focus blurred areas. Unlike lens sharpness, one can get a sense of bokeh from images resized for the web. I'll point out a few other concerns in specific examples.

F/2.8:



While the DP2 lens has decent flare resistance, it flares more than the DP1 lens in my experience. The above photo shows flare with a stong off-axis light source. The hood was employed, and no filter was present. You can also see a blue-green discoloration on the wall in the upper right aspect of the frame.





F/4:



F/2.8:



F/4:



Looking at the right side of the frame, you can see how points of light are rendered sharply as heptagons at this aperture. Some blue-green discoloration is also evident in periphery on the wall.

F/5.6:



There is the occasional doubling of elements, but overall I find the DP2 bokeh to be neutral and generally pleasing.

The issue of blue-green drift in the corners/periphery was present with the DP1 and effectively addressed in a Sigma Photo Pro update. As of yet, the issue persists with DP2 files but is rarely a major issue and can be addressed in postprocessing. A few examples of color in DP2 photos from a recent day out with the family are shown below (click to enlarge).

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In Part 3 of the shootout, we'll take a look at how the Sigma DP2 dynamic range compares to that of the Panasonic GH1 and M. Zuiko 17mm f/2.8.

Readers of this site may recall that the DP1 showed superior dynamic range in an earlier shootout, but the GH1 arguably features the latest and greatest Four Thirds sensor technology to date. How will they compare?

I chose a nearly impossible scene for the sake of comparison. At noon, without a cloud in the sky, there is probably no digital camera that can fully handle this dynamic range in a single exposure:



For comparison, we'll be looking specifically at the two regions highlighted by the yellow boxes above.

Test conditions:

• The GH1 was used in 3:2 aspect ratio.
• Subject distance was adjusted to match framing with the two systems.
• GH1 files were processed in Lightroom (latest version) and subsequently downsized using Photoshop Bicubic Sharper to match the native dimensions of the DP2 files.
• DP2 files were processed in Sigma Photo Pro (latest version).
• All settings were left on defaults.  White balance was not adjusted to match colors, though I experimented with this and found that doing so did not substantially affect the results.

To begin with, a single RAW file was taken with each camera at ISO 100, f/5.6, and 1/50s.

Here are the crops without any exposure adjustments during RAW processing:



Clearly the DP2 is holding highlights better here. The black points are different, but you can actually see the shadow detail better in the DP2 file. This is evident in the stones under the deck (bottom panel).

Now let's see how much highlight detail can be recovered with a -2EV adjustment during RAW processing:



One possible explanation for the much greater highlight detail in the DP2 file is that what Sigma is calling ISO 100 corresponds to a lower actual ISO than what Panasonic is calling ISO 100. This would result in the DP2 file being underexposed relative to the GH1 file.

If that were the reason for the disparity, we would expect greater usable shadow detail in the GH1 file. Let's see what happens when the same files are pushed to +2EV during RAW conversion:



The greater shadow detail is now even more apparent in the DP2 file.

Conclusion: Under identical circumstances at base ISO, a DP1 RAW file simultaneously delivers greater highlight and greater shadow detail.

Next lets see how the two systems handle the same scene at ISO 400, f/11, 1/50s.

Here are the crops without any exposure adjustments during RAW processing:



The same files after a -2EV adjustment during RAW conversion:



Interesting that the ISO 400 DP2 file with a -2EV adjustment retains more highlight information than the ISO 100 DP2 file with a -2EV adjustment. We saw this in the DP1 shootout as well. It suggests that the high ISO DP files are being (partially or fully) pushed in SPP.

Now the same files after a +2EV adjustment during conversion:



Both files are struggling to produce any usable shadow information here. In the top panel, the DP2 still seems to do better.

The bottom line for ISO 400 is unchanged from the bottom line for ISO 100: better dynamic range from the Sigma.

The RAW files used in this comparison can be downloaded below:

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Many in the Serious Compacts community are excited about the new Micro Four Thirds standard. Now there is a site dedicated to nothing but Micro Four Thirds reviews. Check it out at M43reviews.com.

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This content has been moved to the new SeriousCompacts.com.

Click here to go to the new location

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In part 2 of the Sigma DP2 shootout, we'll look at how the DP2 lens performs at a variety of apertures and compare the overall detail captured by the DP2 with that of the Panasonic GH1 and Olympus M. Zuiko 17mm f/2.8 lens.

To begin, I'll explain my choice of RAW processors. The DP2 files were processed using Sigma Photo Pro (latest version) because there are no other RAW processors which demosaic DP2 files at this time. The GH1 files, on the other hand, can be processed using a number of different applications. I chose to use Adobe Lightroom (latest version) because it automatically addresses the considerable barrel distortion of the M. Zuiko lens. In doing so, one loses some resolution, and the blurriest extreme corners of the image get cropped out, but overall I think it gives the fairest comparison to the Sigma DP2.

How much do processing decisions affect apparent detail? Here's an example of an f/2.8 center 100% crop processed with Lightroom (right) compared to the same file processed for maximum apparent detail in Raw Developer (left):



Most of the difference there comes down to sharpening, though I do find that Raw Developer squeezes out a touch more detail.  This is true for every camera I have tried to date.

Other testing details:

• Subject distance adjusted for roughly the same framing with each camera (greater distance for the longer lens)
• GH1 used in 3:2 aspect ratio
• DP2 files upsized using Genuine Fractals 5 to match the native GH1 picture dimensions
• Tripod, self-timer, base ISO, aperture-priority exposure, good light (high shutter speed)

Even looking at just the resized left half of the scene, there is a clear difference between the DP2 and GH1-17mm files at f/2.8:



Let's look next at the 100% crop comparisons, keeping in mind that the DP2 files have been upsized to match the GH1 file sizes.

f/2.8

Center:



More detail in the GH1 file as would be expected with the higher megapixel sensor.

Near edge:



DP2 outclassing the M. Zuiko here and also showing greater lens contrast.  There is some color fringing in the GH1 crop.

Extreme corner:



Impressive wide open performance from the DP2 in the extreme corner of the frame while the M. Zuiko lags far behind.  Again there is some color fringing in the GH1 crop.


f/4

Center:



GH1-17mm looking very good here with the lens resolving sufficiently to take advantage of the higher megapixel sensor.

Near edge:



Zuiko has caught up here in peripheral performance.

Extreme corner:



The Zuiko has improved but has a ways to go still.


f/5.6

Center:



As expected, the higher GH1 sensor is still capturing more detail at this aperture.

Near edge:



Still very close in this zone.

Extreme corner:



DP2 still has an edge in the extreme corner.


f/8

Center:



GH1-17mm still has an edge, but diffraction is bring the level of detail down closer to that of the DP2.

Near edge:



DP2 looks the better of the two here.

Extreme corner:



DP2 is clearly better.


Conclusions:

1. The Sigma DP2 lens has balanced performance across the frame wide open at f/2.8, and by f/4 even the extreme corner peformance is quite good. Anything less would have been a disappointment given the precedent set by the outstanding DP1 lens. 
2. The M. Zuiko 17mm lens leverages the GH1 sensor potential in the center of the frame from f/2.8, puts in a decent peripheral performance stopped down to f/4 or f/5.6, but never quite nails the extreme corner.
3. Softening due to diffraction is evident at f/8 with the Micro Four Thirds kit and not with the DP2.
4. There seems to be higher lens contrast with the DP2 although the contribution of processing by Sigma Photo Pro cannot be ascertained.  Application of wide-radius unsharp mask to a GH1 file gives it a similar look to that of the DP2 files.

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