Conclusions

 



Resolution


As can be seen from the figures given in the table, the ZS40/TZ60 with its higher pixel count shows a higher resolution than the ZS50/TZ70, as expected, although as the lens is zoomed in to longer FLs the decline in resolution is less for the ZS50/TZ70 than the ZS40/TZ60.  Both models show a decline in resolution as the f number approaches f/8 due presumably to the lens and diffraction effects, although again the decline is less for the ZS50/TZ70.


Noise


From the results it can be seen that the ZS50/TZ70 images show significantly less noise than the ZS40/TZ60 at all ISO settings, and the difference is greater at higher ISO settings.  This applies to both JPG and RAW images. The results seem to support the claim by Panasonic that a benefit of one stop is gained by the ZS50/TZ70 with its lower noise compared with the ZS40/TZ60.


The noise plots for the images from the RAW files gave quite smooth curves, and at all ISO settings the ZS50/TZ70 noise was lower than the ZS40/TZ60.  This implies that the ZS50/TZ70’s sensor is inherently less noisy than the ZS40/TZ60’s sensor.  The lower noise shown for the JPG image plots compared with their respective RAW plots represents the amount of noise reduction (NR) that is applied in-camera.  The irregularities in the JPG plots show that different amounts of NR are applied at different ISO settings, and that appears to vary between the two models.


The trends in noise with ISO setting as revealed by the plots can also be seen in the image crop comparisons, where at the higher ISO settings the ZS40/TZ60 crops show an amount of noise which appears to be visibly about one stop greater than the noise of the ZS50/TZ70 at the same ISO setting.


Comparison Images


Comparing the images taken with both models under the same conditions showed that despite the

ZS50/TZ70’s somewhat lower resolution, its lower noise meant that overall the IQ of the two models was fairly similar, particularly at longer FLs.  At or near WA the ZS40/TZ60 has an advantage at low ISO settings because of its significantly higher resolution in that part of the zoom range.


Summing Up


The ZS50/TZ70 provides improved image quality compared with the ZS40/TZ60 in terms of significantly less noise in the images, particularly at higher ISO settings.  This is at the cost of a somewhat lower resolution, which is more apparent at short focal lengths and low ISO.  The results suggest that overall there is not a great deal of difference between the two models.  In terms of features, the ZS50/TZ70 has an improved EVF with an eye sensor, whereas the ZS40/TZ60 has a quite adequate but lower resolution EVF without an eye sensor; and the ZS40/TZ60 has GPS whereas the ZS50/TZ70 does not.






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