TIPA Camera Test Online: Sigma DP2x

By TIPA

Cameras

17 August 2011 10:00

The Sigma DP2x is the successor to the DP2s and is based on the same Foveon X3 sensor. It uses a new image processing unit for higher speed (startup time, shutter delay etc.). Its special sensor records images with 4.7 MP but detects RGB information for every single pixel, and Sigma indicates the DP2x as a 14 MP camera.

Comments on Handling

The Sigma DP2x is a compact camera with a (nearly) APS-C sized image sensor. The 20.7 x 13.8 mm sized Foveon X3 sensor doesn’t use the standard Bayer RGB pattern because it is able to identify the whole RGB information in every single pixel. Therefore the camera doesn’t have colour interpolation to create the RGB image and is the reason why Sigma/Foveon specify the sensor resolution with 14 MP. This pixel value is based on the 2640 x 1760 pixel resolution multiplied with 3 (for three RGB values in every single pixel).

The camera offers a fixed focal length of 41 mm (35 mm film equivalent) with a fast aperture (F1:2.8) and very high quality. The DP2x showed a very good performance in the resolution tests and offers a handling which closely follows the handling of a SLR system. It offers all standard exposure programs like P, S, A and M which are chosen with the help of the mode dial on top of the body. For manual focusing the photographer has to use a small dial. This is more comfortable than manual focusing with the menu buttons (compact cameras) but less handy than working with a focus ring on the lens system.

The main difference between the forerunner Sigma DP2s is the new image processing unit in the DP2x. The camera showed a good performance in our handling test because the startup time, shutter delay time, focusing and exposure setting are noticeably accelerated.

The camera only has a 2.5 inches sized LCD screen with a resolution of only 230,000 RGB dots. This is far less than current SLR systems in the same price range will offer. The LCD screen is used as control centre for the menu and as an electronic view finder (the camera has no optical viewfinder or ELV). A standard (4 way) cursor field is used for menu navigation. The camera offers a “QS” button which allows the user to switch between two function menus for the most important image parameters (resolution, file format, ISO speed setting, flash mode etc.). This helps to change these parameters very fast and efficiently.

The camera has two “zoom” buttons in the upper right area of the rear of the body. These buttons can be used for zooming into the image when in review mode. As the camera’s lens is a fixed focal length, these buttons are used to set shutter-speed setting when in recording mode.
 

Test shots

Click image to enlarge.

The portrait shot shows the very crisp and clear reproduction of fine details in hairs or in the fabric of the model’s t-shirt. The bluish background is caused by the automatic white balance system which tends to create a cooler look especially when using light systems based on florescent lights.

Click image to enlarge.

The standard testbox shot shows a very nice reproduction, even of very difficult elements like the metal sieve and the Siemens’ stars. The colors are natural looking, although the automatic white balance system causes a slightly cooler or greenish touch.

Comments on Image Quality

Colour:
The automatic white balance system causes a very cool look in many of our test shots - especially when taking images under florescent light, where it will cause a real bluish touch. You will notice that in our portrait shot, while the standard test-box shot shows more natural and realistic colours. Taking images in raw mode or using manual white balance settings is advisable for nearly all Sigma cameras.

The Gretag Macbeth test chart was reproduced with this light bluish touch, but the level of colour errors in nearly all nuances is still very low. This is due to the saturation of 102.9 percent which is very good. Most other cameras will reproduce the chart with much higher saturated colours.

Sharpness:
The DP2x offers very crisp and clear images which are absolutely free of moirés and aliasing artifacts which are caused by colour interpolation in images taken with Bayer pattern CMOS/CCDs. The high quality lens system and the sensor are able to convert the nominal resolution of 2640 x 1760 pixels almost completely in to real image details (resolution in our tests was 1640 lines per picture height). These images provide a lot of potential to interpolate image resolution. We achieved really good results with impages interpolated to 150 percent which means an image resolution of about 10 MP. When converting these images to 14 MP resolution you will get image results with a slightly smoother look.

Nevertheless, the original JPEGs in 4.7 MP resolution have a very crisp look. You will notice that in our portrait shot because hairs, eye lashes and the structure of the model’s clothing are reproduced nearly perfectly.

Noise:
When taking JPEG images the camera offers ISO speed settings between ISO 50 and ISO 800. Only when shooting in raw mode will it allow you to use ISO 1600 and ISO 3200 settings. Up to ISO 400 the luminance noise factor is comparable to noise factors of SLR cameras with APS-C-sized image sensors. It will cross the 1.0 level in ISO 800 mode which is worse than in images taken with most SLR systems. In addition the “Noise spectrum” is on a very high level, so image noise is clearly noticeable in photos taken with ISO 400 and higher. If you are using ISO 1600 and ISO 3200 in raw mode you may want to use an intense anti noise filtering in Sigma’s “Photo Pro 5” software or in Adobe Photoshop/Lightroom.

Opinion

Pros:
     + very good transformation of nominal sensor resolution into real image details
     + no moirés or aliasing artifacts
     + compact and robust body
     + manual control for exposure settings and focusing

Cons:
     - missing interchangeable lens system, no zoom lens
     - small LCD with low resolution
     - low video resolution (320 x 240 pixel)

To download the PDF specifications sheet for the Sigma DP2x, click HERE.

About TIPA

The Technical Image Press Association (TIPA) is a non-profit oranisation made up of a worldwide family of independent photo & imaging magazines with the most expert editors.

TIPA uses BetterNet GmbH in Heidelberg, Germany to perform routine digital camera tests based on an independent and objective testing method. The TIPA sponsored tests range from small compact cameras to popular DSLRs and even up to high-tech medium format models.

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