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Canon EF-S 18-200mm f3.5-5.6 IS Gordon Laing, January 2009
 

Canon EF-S 18-200mm IS results : Real-life resolution / Corner wide / Corner tele / Studio Resolution / Geometry / Vignetting


Canon EF-S 18-200mm IS Vignetting / Light fall-off

To measure the Canon EF-S 18-200mm IS's vignetting and light fall-off we photographed a white target with a highly diffused custom filter. The lens was manually focused to infinity and tested at its shortest and longest focal lengths with its aperture wide open. The images were shot in RAW mode to avoid any in-camera corrections, then analysed with Imatest and the full areas presented here at a reduced resolution. This time, bigger percentages are better. Results for rival lenses are shown at the bottom of this page; note the results for the EF-S 18-55mm here are for the older non-IS version.


Canon EF-S 18-200mm IS vignetting zoomed-out
 
Canon EF-S 18-200mm IS vignetting zoomed-in
EF-S 18-200mm IS at 18mm f3.5
Mean corner fall-off: 37.7%
EF-S 18-200mm IS at 200mm f5.6
Mean corner fall-off: 41%


Zoomed-out to 18mm and with its aperture wide open, light falls-off in the corners of the frame to 37.7% of the centre measurement. This is significantly worse than any of the other lenses shown below, including the EF-S 17-55mm IS and EF-S 17-85mm IS which fell-off to 46.8% and 57.8% respectively. The bottom line here is darkening in the corners is quite apparent on the EF-S 18-200mm IS when zoomed-out, and you'll even see it in the viewfinder when composing a shot which contains flat areas of colour like a blue sky.

Zoomed-into 200mm with its aperture wide open, light falls-off in the corners to 41% of the centre measurement, which again is much worse than the other lenses compared below. The next worse of the group is the EF-S 17-55mm with 60.8% light fall-off when zoomed-in, but lest we forget, this is an optically bright lens with an f2.8 aperture, so it has a good excuse. The other three lenses score in the high seventies or low eighties. So once again, darkening in the corners is also apparent with the EF-S 18-200mm IS when zoomed-in.

These are some of the worst scores we've measured for light fall-off on a lens which doesn't have a bright focal ratio, and its super-zoom range can't be used as an excuse either - after all, the Nikkor DX 18-200mm VR's light fall-off was measured at 62.2% and 73.4% when zoomed-out and in respectively.

It's perhaps no coincidence then the EF-S 18-200mm IS was launched alongside Canon's first body featuring in-camera peripheral illumination correction. With this feature enabled on the EOS 50D, we repeated the tests and measured light fall-off on in-camera JPEGs to be much more acceptable - indeed barely noticeable - at 82.5% and 85.1% when zoomed-out and in respectively. Peripheral illumination correction can also improve the results on all of Canon's lenses, and luckily for those without the latest bodies, it can also be applied to RAW files using Canon's Digital Photo Professional software. Bear in mind though the software is simply digitally brightening the corners, which in turn can reveal greater noise in these areas, especially if the shot was taken at higher sensitivities.

But while light fall-off can now be corrected quite effectively after the event, the EF-S 18-200mm IS is still performing poorly in this test, and this is one aspect which cannot be blamed on its long optical range as similar models don't suffer anywhere near as badly. That's enough for our formal tests now, so let's check out some more real-life sample images in our Canon EF-S 18-200mm IS Gallery.

Canon EF-S 18-200mm Vignetting / Light fall-off compared to other lenses

Canon EF-S 18-55mm f/3.5-5.6 vignetting wide / tele
 
Canon EF-S 17-85mm f/4-5.6 IS vignetting wide / tele
 
 
 
EF-S 18-55mm at 18mm f3.5
Mean corner fall-off: 68.8%
 
EF-S 18-55mm at 55mm f5.6
Mean corner fall-off: 83.8%
 
EF-S 17-85mm IS at 17mm f4
Mean corner fall-off: 57.8%
 
EF-S 17-85mm IS at 85mm f5.6
Mean corner fall-off: 77.5%


Canon EF-S 17-55mm f/2.8 IS vignetting wide / tele
 
Canon EF 24-105mm f/4L IS (APS-C sensor) vignetting wide / tele
 
 
 
EF-S 17-55mm IS at 17mm f2.8
Mean corner fall-off: 46.8%
 
EF-S 17-55mm IS at 55mm f2.8
Mean corner fall-off: 60.8%
 
EF 24-105mm IS at 24mm f4
Mean corner fall-off: 84.4%
 
EF 24-105mm IS at 105mm f4
Mean corner fall-off: 83.6%


Canon EF-S 18-200mm IS results : Real-life resolution / Corner wide / Corner tele / Studio Resolution / Geometry / Vignetting


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