ZS20 Resolution Testing 3

 


Testing of the Variation of ZS20 Resolution with ISO Setting


Previously I had tested the resolution of my FZ38 with change of ISO setting, as described here, using a focal length (35mm equiv.) of 176mm and an aperture setting of f/4.0.  I used the same method to investigate how the resolution of the ZS20 changed with ISO setting, and I also used the same focal length (176mm) and an aperture of f/5.4, since that was the widest available at that focal length on the ZS20.  I took shots at each available ISO setting from ISO 100 to ISO 3200, and prepared 300% crops as described in the previous section.  The comparison images are shown below. (Click on an image to see the full sized view.)



Above: ZS20, 176mm, f/5.4, Coloured Es Chart


The actual resolution figures assessed from the above images are given below.


ISO            Resolution (LWPH)


100            1900

200            1900

400            1900

800            1800

1600           about 1700

3200           about 1500                  



Above: ZS20, 176mm, f/5.4, Tapering lines chart


The trend for the tapering lines is similar to that of the Es chart with the resolution decreasing slowly until about 800 ISO, followed by a larger decrease at 1600 ISO, and then a very marked decrease at 3200 ISO.  The increase in noise follows a very similar pattern, with 3200 ISO showing a lot of noise, accompanied by some yellow blotching.



Above: ZS20, 176mm, f/5.4, Plane fuselage


These crops help to show how the noise increases with ISO setting in a subject with broad and fine detail.  The noise increases at first slowly up to about 800 ISO, then more visibly at 1600 ISO and then becoming very obvious at 3200 ISO.  In addition, there is increasing loss of some of the fine details on the plane from about 800 ISO upwards to 3200 ISO when much of the detail is lost.



Comparing the ZS20 with the FZ35/38

I have copied below, for comparison, the coloured Es chart crops from the FZ38 testing.  For the FZ38 the highest available ISO setting is 1600 ISO (the crops show 100 ISO at the LHS, and 1600 ISO at the RHS).



Above: FZ38, 176mm, f/4.0, Coloured Es Chart


The actual resolution figures assessed from the above images are given below.


ISO            Resolution (LWPH)


100            2000

200            1900

400            1900

800            1800

1600           about 1800


As can be seen, for both camera models, the resolution for the black Es decreases only gradually with ISO and only decreases markedly at 3200 for the ZS20.  However, in the case of the FZ38, there is obvious colour smearing and loss of colours at 800 ISO, and this occurs to a greater extent at 1600 ISO.  In contrast, the ZS20 shows much better colour retention, and does not show the smearing of colours that is apparent at high ISO with the FZ38.  For the ZS20 the fading of colours does not become very evident until 1600 ISO, and is worse at 3200 ISO.  The noise levels increase with increasing ISO and there is considerably more noise in the ZS20 images than the FZ38 images at the same ISO settings.




Continue to an Overall Comparison of the ZS20 and the FZ35/38


Continue to Reducing Noise in ZS20 Images


Continue to ZS20 Colour Contrast Tests


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