Sabtu, 06 Juli 2013

Nikon 1 V2 Review Part 3 Image Quality


Marina, Nikon 1 V2, 10-100mm f4-5.6 lens at 30mm. 

Introduction   The V2 has many features and capabilities which might make it attractive to the enthusiast photographer seeking good performance and image qualiy in a wide range of conditions. But the bottom line for any camera's appeal is it's image quality.

DXO Mark Score  DXO (dxo.com)  rates the V2 image quality at 50. This is in compact camera territory. The Sony RX100 Mk 2, with the same size sensor, scores 67, the Nikon 1 S1 with 10 mpx sensor scores 56 and the Nikon Coolpix P330 with a much smaller 1/1.7" sensor scores 54.  So, on the numbers the V2 doesn't look very appealing.  However a DXO Mark score is not the final word about image quality.
Noise    I compared the V2 in real world conditions with two cameras which I had on hand at the time, a Lumix G5 and Lumix GH3, both Micro 4/3 system cameras with a substantially larger sensor.  I used RAW files converted in Adobe Camera Raw 8.1 at default settings. You would expect the M4/3 cameras to beat the V2 and they did but but not by a great margin.
With the V2 at base ISO, I found noise easily visible in even toned shadow areas. This was not the case with the m4/3 cameras.
At high ISO levels in the range 1600-3200-6400, I found that  the V2 gave up about 0.7 stop to the G5 and  about 1.3 stops to the GH3.  In other words an ISO 1600 photo with the V2 had about the same noise level as one taken at ISO 2500 with the G5 and 4000 with the GH3.
Nikon V2
Lumix G5
Lumix GH3

Dynamic RangeUsing RAW files converted in ACR 8.1 and working the sliders to best effect, there was surprisingly little difference between the three cameras in the amount of highlight and shadow detail which could be extracted from a scene with high subject brightness range.  The main difference lay in the amount of noise present in the shadow areas. Images from the V2 had more noisy shadows then those from the G5 which in turn were more noisy than the GH3.
Exposure  I used Matrix Metering in all conditions. Over more than 2000 exposures I found very few which did not make best use of the available dynamic range of the sensor. Overtly wrong exposures were rare.
White Balance  With the camera set to Auto White Balance for all tests I found little about which to complain in any set of conditions interior or exterior.
Color  Colors were generally accurate in all conditions with few adjustments being required in ACR.
Resolution  Some years ago my main camera was a Canon EOS 20D with  an 8 Mpx sensor. I discovered that images of quite high resolution could be made with this camera given a good quality lens. The V2 has a 14 Mpx sensor which should be able to deliver very detailed images with a lens of sufficient quality. The 10-100mm f4-5.6 lens which I used for this series of tests appeared able to reveal most of the sensor resolution at it's wide end but not at the long end.
Depth of Field, ISO and Image Quality  For any given angle of view and lens aperture, a small sensor camera will exhibit more depth of field than one with a large sensor. Whether this is desirable or otherwise depends on one's requirements. For the landscape/documentary/architecture  photographer large depth of focus can be desirable as the job specification may require all subject elements to be rendered sharply. However for the portraitist, a softly blurred background is more likely to appeal.  
In many general photographic situations the IQ disadvantage suffered by small sensor cameras can be offset by the ability to use wider apertures for the same depth of field. Compare a full  frame camera to one with a Nikon CX sensor. Let us say the full frame camera requires f11 for sufficient depth of field. At the same framing the CX camera will only require f4 for the same depth of field.  This means the CX camera can use a higher shutter speed, removing the need for a tripod, or a lower ISO setting, or both.  When just ISO is used to achieve the same effective exposure, if the full frame camera needed ISO 1600, the CX camera can use ISO 200.  Now look at the DXO Mark scale of image quality ratings. You will see that 15 points on the scale is equivalent to one stop of image quality. The best full frame cameras score about 95, the V2 scores 50, which is 3 stops lower. The point of all this is that in some situations you could achieve almost the same image quality with the smaller sensor as with the larger one, in a more compact, lighter, less expensive package.  

Summary  Overall image quality of the V2 in real world practice is in line with the DXO Mark score. However images of excellent quality can be made if the ISO setting is kept to the lowest setting consistent with avoiding camera shake.

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