SX700 Image Evaluations

 


I compared the images from the SX700 tests in the same way as for the ZS40 in the previous section.


Calculation of Resolution


The resolution is obtained from the coloured Es chart as explained earlier.  For the SX700, the resolution in lines per picture height (LPH) = 3456/line thickness.


Resolution and Focal length


For the central coloured Es test image at 25mm (full WA), f/3.2 and 100 ISO, the lowest resolved E is on the 1.5 row, therefore the resolution is 3456/1.5, which is about 2300 LPH. 


For the central coloured Es test image at 750mm (max tele), f/6.9 and 100 ISO, the lowest resolved E is on the 1.7 row, therefore the resolution is 3456/2.0, which is about 2000 LPH.


Resolution and Aperture at the Image Centre


Below is a comparison of test image crops of the central coloured Es chart at different aperture settings at 25mm FL and 100 ISO (click on the image for a larger version):



25mm, 100 ISO Aperture Series


As for the ZS40, there is a gradual decline in resolution as the f number increases, as a result of the effects of diffraction.


Because the SX700, like the the FZ40, is limited in its widest available apertures, the resolution decreases as the FL increases.  Therefore the resolution at 25mm and f/3.2 (2300 LPH) is higher than the resolution at 720mm and f/6.4 (2000 LPH).



Resolution and ISO setting


Below is a comparison of test image crops of the central coloured Es chart at different ISO settings at 25mm FL and f/3.2 (click on the image for a larger version):



25mm, f/3.2 ISO Series Es Chart


Unlike the ZS40, as the ISO setting increases, while there is a decrease in resolution and an increase in noise, the changes are more gradual throughout and are somewhat less severe.  The smearing of the Es and loss of colours also appear somewhat less than for the ZS40.


Below is a comparison of test image crops of part of the circuit board and yellow fabric at different ISO settings at 25mm FL and f/3.2 (click on the image for a larger version):



25mm, f/3.2 ISO Series Crops


The crops above of objects at a larger scale give a visual appreciation of the gradual decrease in IQ as the ISO setting increases.



Resolution in the Image Corners


The crop below shows a 100% crop from the top left hand corner of the test image taken at 25mm, f3.2,and 100 ISO:


Unlike the equivalent crop from the ZS40 image, the corner of the image shows very little blurring or distortion, and the other corners of this image are as good as this one or better.


However, examination of the corners of Sx700 test images taken at longer focal lengths show some blurring.   Therefore the SX700 appears better in the corners at wide angle than the ZS40 but not quite as good in the corners as the ZS40 at longer focal lengths.


It can be concluded from the above results that the maximum resolution is obtained with the SX700, as with the ZS40, at or near the image centre, at low FL, widest aperture, and 100 ISO setting.







Continue to Comparisons between ZS40 and SX700


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