ZS20/TZ30 Resolution Testing 1

 


In This Section:

Testing of the ZS20 Resolution with Aperture and Focal Length

Testing of the ZS20 Resolution with ISO Setting

Comparison of the ZS20/TZ30 and the FZ35/38



Testing of the ZS20 Resolution with Aperture and Focal Length


I carried out tests to determine the variation of the resolution with aperture and focal length on the ZS20 using the method and test chart I had previously used for my FZ38, as described in detail in this section here.


I tested the full range of available apertures at the focal length settings (35mm equivalent) of 24mm (full WA), 34mm, 176mm, 249mm, 386mm (the maximum zoom setting of the ZS15/TZ25) and 480mm (maximum tele zoom).  I had previously determined the available aperture values at each of the 45 zoom settings on the ZS20 as shown here.


From the chart images I determined the resolution in LWPH (line widths per picture height) for each aperture and focal length.  In general, as found previously, it was easier to make the assessments using the Es chart rather than from the tapering lines chart.  (My thanks to Dr J. C. Brown for his assistance with these assessments.)  The measurements were made from the central zone of the chart images, from the region in the cropped example chart image as shown below.



Above: Central area of the chart which was used for the measurements


From the test chart images I assembled comparison images constructed from 300% crops to enable accurate assessment of the resolution, and to make it simple to view the changes as the aperture settings (f numbers) increased.  Note: the black tapering lines charts were rotated by 90 degrees to enable them to fit.  I also prepared crops from an area of the plane fuselage to visualise how change in aperture affected the detail at various scales.


The comparison images for 24mm focal length (full WA, 1x zoom) are shown below.  (Click on an image to see the full sized version.)



Above:  24mm, Coloured Es chart, 100 ISO, f/3.3-f/5.0 @ 300%



Above:  24mm, Coloured Es chart, 100 ISO, f/5.6-f/8.0 @ 300%



Above: 24mm, Black tapering lines chart, 100 ISO, f/3.3-f/5.0 @ 300%



Above:  24mm, Black tapering lines chart, 100 ISO, f/5.6-f/8.0 @ 300%



Above:  24mm, Plane fuselage, 100 ISO, f/3.3-f/5.0 @ 300%



Above:   24mm, Plane fuselage, 100 ISO, f/5.6-f/8.0 @ 300%



The comparison images for 480mm focal length (full tele, 20x zoom) are shown below.  (Click on an image to see the full sized version.)



Above:  480mm, Es chart, 100 ISO, f/6.4-f/8.0 @ 300%



Above:  480mm, Tapering lines chart, 100 ISO, f/6.4-f/8.0 @ 300%



Above:  480mm, Plane fuselage, 100 ISO, f/6.4-f/8.0 @ 300%


The results from the chart assessments are shown in the next section.



Continue to the Results


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