CanonUser
22nd of December 2003 (Mon), 23:57
This is a cut and paste comment found in another board. Don't shoot the messenger...
"At
"www.dforum.de/Technik/Objektivtest/Objektive/Canon/EF-S_18-55.jpg"
and
"www.dforum.de/Technik/Objektivtest/Objektive/Canon/4_0-17-40_L_USM.jpg"
you can compare test results of Canon's 17-40L and 18-55. "Bildmitte" means picture center, and "Bildrand" means picture corner. The red dots are the resolution limits. The green dots are where the MTF is 50%, showing how contrasty the lens is.
The only full size crops I have seen posted (at f/4) showed the 18-55 was ever so slightly sharper than 17-40L in the center, and Canon's MTF charts implied the same thing. "Impossible" was many people's response.
Well, just look at the red dots on the "Bildmitte" charts for the 2 lenses at 17 and 18 mm - the resolution limit. Surprise, surprise. The 18-55 is slightly SHARPER than the 17-40L at f/4. Stays that way as you stop down.
Like I suspected from Canon's MTF charts, the 17-40L is sharper in the corners at f/4. Stop down a bit and the difference disappears.
At 24/28mm (for the 17-40L/18-55), the 18-55 again wins slightly in the center. 17-40L wins in the corners wide open. The gap disappears at smaller apertures.
At 33/35mm, they're virtually identical in the center. 17-40L wins in the corners at larger apertures, with the gap disappearing at smaller apertures.
At 40/55mm, they're virtually identical in the center. 17-40L wins in the corners at larger apertures, with the gap disappearing at medium apertures.
The 17-40L is contrastier most of the time, as seen by the green dots. To compensate, use local contrast enhancement for the 18-55 images (unsharp mask with Amount 10-20%, Radius 50, Threshold 0).
If you make large full frame enlargements, you'll see the difference in the corners at large apertures. At smaller apertures, those corner differences disappear. Of course, if you get standard sizes (8x10, 11x14, 16x20 20x24), those corners have been cropped out.
$800 versus $100. EXPENSIVE CORNERS! If you make your living doing this, sure it's worth it. For the rest of us...well, you decide."
DR owners, Happy Holiday...
"At
"www.dforum.de/Technik/Objektivtest/Objektive/Canon/EF-S_18-55.jpg"
and
"www.dforum.de/Technik/Objektivtest/Objektive/Canon/4_0-17-40_L_USM.jpg"
you can compare test results of Canon's 17-40L and 18-55. "Bildmitte" means picture center, and "Bildrand" means picture corner. The red dots are the resolution limits. The green dots are where the MTF is 50%, showing how contrasty the lens is.
The only full size crops I have seen posted (at f/4) showed the 18-55 was ever so slightly sharper than 17-40L in the center, and Canon's MTF charts implied the same thing. "Impossible" was many people's response.
Well, just look at the red dots on the "Bildmitte" charts for the 2 lenses at 17 and 18 mm - the resolution limit. Surprise, surprise. The 18-55 is slightly SHARPER than the 17-40L at f/4. Stays that way as you stop down.
Like I suspected from Canon's MTF charts, the 17-40L is sharper in the corners at f/4. Stop down a bit and the difference disappears.
At 24/28mm (for the 17-40L/18-55), the 18-55 again wins slightly in the center. 17-40L wins in the corners wide open. The gap disappears at smaller apertures.
At 33/35mm, they're virtually identical in the center. 17-40L wins in the corners at larger apertures, with the gap disappearing at smaller apertures.
At 40/55mm, they're virtually identical in the center. 17-40L wins in the corners at larger apertures, with the gap disappearing at medium apertures.
The 17-40L is contrastier most of the time, as seen by the green dots. To compensate, use local contrast enhancement for the 18-55 images (unsharp mask with Amount 10-20%, Radius 50, Threshold 0).
If you make large full frame enlargements, you'll see the difference in the corners at large apertures. At smaller apertures, those corner differences disappear. Of course, if you get standard sizes (8x10, 11x14, 16x20 20x24), those corners have been cropped out.
$800 versus $100. EXPENSIVE CORNERS! If you make your living doing this, sure it's worth it. For the rest of us...well, you decide."
DR owners, Happy Holiday...