11-08-2011, 02:56 PM
[quote name='Studor13' timestamp='1320762957' post='12764']
OK, so for those out there who rely (solely) on Photozone's resolution numbers, here are my own non-scientific results at 35mm (large files 6MB) - about 2m from subject to lens (60x focal length):
18-35mm @f4.5
[url="http://www.studor13.si/music/photos/PZ/1835-35-f45.JPG"]http://www.studor13....1835-35-f45.JPG[/url]
35mm AIS @f4
[url="http://www.studor13.si/music/photos/PZ/35AIS-f2-f4.JPG"]http://www.studor13....35AIS-f2-f4.JPG[/url]
18-55mm II @f4.5
[url="http://www.studor13.si/music/photos/PZ/35Kit-f45.JPG"]http://www.studor13....Z/35Kit-f45.JPG[/url]
18-55mm VR @f5
[url="http://www.studor13.si/music/photos/PZ/35VR-f5.JPG"]http://www.studor13..../PZ/35VR-f5.JPG[/url]
The results at other focal lengths are in favor of the 18-35mm universally, except wide open at 18mm.
As I have said (twice), it is beyond believe that PZ can claim that the resolution in the corners of the 18-55 VR at 35mm wide open can be almost double that of the 18-35 also at 35mm and also wide open!
[/quote]
The numbers quoted in the lens tests are non-representative for real use. They actually go way beyond what is possible in real life, because it is just a way of testing, and only allows some kind of ranking of lens sharpness, that's all. In real life, using 9% contrast (Rayleigh criterion), no lens gets better than the corresponding diffraction limits, and only very few do. Divide 1600 by the aperture number used (e.g. 4 for F/4), and you get the maximum resolution in lp/mm, double that to get the number of pixels, as a diffraction limit. Only the best photographic lenses out there are diffraction limited at F/4 (IOW, are as good or better than 1600/4 = 400 lp/mm), most will come in at F/5.6 or F/8, and a lens less good at F/11 or F/16.
Considering you only need 40 lp/mm to better the best amateur colour negatives (20 lp/mm for average!), and 60 lp/mm for the best professional ones, these numbers are rather irrelevant.
Kind regards, Wim
OK, so for those out there who rely (solely) on Photozone's resolution numbers, here are my own non-scientific results at 35mm (large files 6MB) - about 2m from subject to lens (60x focal length):
18-35mm @f4.5
[url="http://www.studor13.si/music/photos/PZ/1835-35-f45.JPG"]http://www.studor13....1835-35-f45.JPG[/url]
35mm AIS @f4
[url="http://www.studor13.si/music/photos/PZ/35AIS-f2-f4.JPG"]http://www.studor13....35AIS-f2-f4.JPG[/url]
18-55mm II @f4.5
[url="http://www.studor13.si/music/photos/PZ/35Kit-f45.JPG"]http://www.studor13....Z/35Kit-f45.JPG[/url]
18-55mm VR @f5
[url="http://www.studor13.si/music/photos/PZ/35VR-f5.JPG"]http://www.studor13..../PZ/35VR-f5.JPG[/url]
The results at other focal lengths are in favor of the 18-35mm universally, except wide open at 18mm.
As I have said (twice), it is beyond believe that PZ can claim that the resolution in the corners of the 18-55 VR at 35mm wide open can be almost double that of the 18-35 also at 35mm and also wide open!
[/quote]
The numbers quoted in the lens tests are non-representative for real use. They actually go way beyond what is possible in real life, because it is just a way of testing, and only allows some kind of ranking of lens sharpness, that's all. In real life, using 9% contrast (Rayleigh criterion), no lens gets better than the corresponding diffraction limits, and only very few do. Divide 1600 by the aperture number used (e.g. 4 for F/4), and you get the maximum resolution in lp/mm, double that to get the number of pixels, as a diffraction limit. Only the best photographic lenses out there are diffraction limited at F/4 (IOW, are as good or better than 1600/4 = 400 lp/mm), most will come in at F/5.6 or F/8, and a lens less good at F/11 or F/16.
Considering you only need 40 lp/mm to better the best amateur colour negatives (20 lp/mm for average!), and 60 lp/mm for the best professional ones, these numbers are rather irrelevant.
Kind regards, Wim
Gear: Canon EOS R with 3 primes and 2 zooms, 4 EF-R adapters, Canon EOS 5 (analog), 9 Canon EF primes, a lone Canon EF zoom, 2 extenders, 2 converters, tubes; Olympus OM-D 1 Mk II & Pen F with 12 primes, 6 zooms, and 3 Metabones EF-MFT adapters ....