Resolution Tests

The table below shows the JPG Resolution at base ISO and widest aperture in LPH (lines per picture height) as calculated from the resolution chart test images:

As can be seen, the resolution of the ZS50/TZ70 is below that of the ZS40/TZ60 at all three of the tested focal lengths.  However, the ZS50/TZ70 shows less decline in resolution as the lens is zoomed in to longer FLs than does the ZS40/TZ60.  The ZS40/TZ60 shows a resolution of 300 LPH higher at 40mm but only 100 LPH higher at maximum zoom.

Noise Tests

Plots of noise versus ISO for JPG and RAW at 40 mm EFL and f/3.8 are shown in the graph below (click on the image for a larger view):

Noise versus ISO setting

The RAW plots are seen to be quite smooth curves which, when plotted logarithmically, give lines which are almost straight, as would be expected for a normal gain response.  At all ISO settings the noise for the ZS40/TZ60 is higher than that of the ZS50/TZ70, for both RAW and JPG.

The lower noise shown at a particular ISO setting for the JPG compared with the RAW is a measure of the amount of noise reduction that is applied in-camera during the JPG processing.  As can be seen that varies considerably for both models.

Overall, the curves for JPG appear to validate Panasonic’s claim of an improvement in noise of about one stop for the ZS50/TZ70 over the ZS40/TZ60.  That is also borne out from examining the ISO series from the test images for both models.  Below are ZS50/TZ70 image crops for the ISO series at 40mm, f/3.8 (click on the image for the 100% view):

Above: Image crops from the ZS50/TZ70 ISO series

Below are ZS40/TZ60 image crops for the ISO series at 40mm, f/3.8 (click on the image for the 100% view):

Above: Image crops from the ZS40/TZ60 ISO series

It can be seen that there is more noise visible in the images for the ZS40/TZ60 compared with the ZS50/TZ70, and that at the higher ISO settings the noise in the ZS40/TZ60 is about equal to that seen in the ZS50/TZ70 images of one stop higher in ISO setting.

Framing Adjustment Comparisons

The images provided on the previous page allow the two models to be compared for IQ in different ways in relation to camera to chart distance, EFL and framing.  Below are comparison crops from one of the pairs which were taken with both models set at 400mm EFL but with the distance adjusted to yield the same framing for both.  As the ZS50/TZ70 image is smaller (4000 x 3000 px) than the ZS40/TZ60 image (4896 x 3672 px) I have upsized the ZS50/TZ70 to match the size for comparison (click on the image for the full sized view): 

ZS50/TZ70 versus ZS40/TZ60, 400mm EFL, base ISO

It can be seen that there is more visible noise in the ZS40/TZ60 image, especially in the shadow areas and the darker parts of the circuit board.  Despite the lower resolution of the ZS50/TZ70, the lower noise in that image allows detail in the darker areas to be seen somewhat more clearly than the ZS40/TZ60 as they are not obscured by noise.  

It is also apparent that the ZS40/TZ60 image has more in-camera sharpening applied than in the image from the other model.  This is more obvious when images from the 40mm EFL tests are examined at 100%, whereby visible sharpening haloes around high contrast edges can be seen in the ZS40/TZ60 images but not in the ZS50/TZ70 images.

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