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Canon PowerShot G7 wide-angle uniformity comparison
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To measure and compare the Canon PowerShot G7's
lens vignetting and light fall-off we photographed a white target with a
highly diffused custom filter using it and a number of rival models.
Here are the results for each camera with their built-in or kit lenses set to their
widest focal lengths with the apertures wide open and the focus set to infinity.
The images were analysed with Imatest and the full areas presented here
at a reduced resolution. Bigger percentages are better.
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7.4-44.4mm at 7.4mm f2.8
Mean corner fall-off: 73% |
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| The image above was taken with the Canon PowerShot G7 zoomed-out to 7.4mm with its aperture wide open. Here the light gently falls off in the corners to an average of 73% of the center
measurement, which is a small improvement over the PowerShot A640 and the EOS 400D / XTi kit lens, although slightly below that of the Panasonic DMC-FZ50. |
Canon PowerShot A640 |
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Canon 400D / XTi
(using EF-S 18-55mm) |
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Panasonic DMC-FZ50 |
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7.3-29.2mm at 7.3mm f2.8
Mean corner fall-off: 67% |
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18-55mm EF-S at 18mm f3.5
Mean corner fall-off: 68.8% |
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7.4-88.8mm at 7.4mm f2.8
Mean corner fall-off: 76.7% |
Canon PowerShot G7 telephoto uniformity comparison
 |
|
To measure and compare the Canon PowerShot G7's
lens vignetting and light fall-off we photographed a white target with a
highly diffused custom filter using it and a number of rival models.
Here are the results for each camera with their built-in or kit lenses set to their
longest focal lengths with the apertures wide open and the focus set to
infinity.
The images were analysed with Imatest and the full areas presented here
at a reduced resolution. Bigger percentages are better. |
7.4-44.4mm at 44.4mm f4.8
Mean corner fall-off: 81.2% |
| |
The image above was taken with the Canon PowerShot G7 zoomed-in to 44.4mm with its aperture wide open. Here the light falls off in the corners to an average of 81.2% of the center
measurement, which while again a slight improvement over the PowerShot A640, is slightly below that of the EOS 400D / XTi kit lens and the Panasonic DMC-FZ50. The important thing is while technically measurable, the G7's light fall-off is little to worry about and barely visible in practice. |
Canon PowerShot A640 |
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Canon 400D / XTi
(using EF-S 18-55mm) |
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Panasonic DMC-FZ50 |
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7.3-29.2mm at 29.2mm f4.1
Mean corner fall-off: 77.7% |
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18-55mm EF-S at 55mm f5.6
Mean corner fall-off: 83.8% |
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7.4-88.8mm at 88.8mm f3.7
Mean corner fall-off: 86.5% |
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