LSHorwitz1
Senior Member
I first want to thank everybody for replying with such an outstanding and informative set of replies. I have learned a lot here (and realize how poorly I understand all of this!).
My practical reason for posing this question originally was the basic confusion I had as to whether buying the 24-105L would gain me anything at all in resolution on my T1i when compared to the option of buying the new 15-85.
I totally understand that these are 2 entirely different lenses, and there are good reasons other than resolution to prefer one to the other. Among these differences are range of zoom, build quality, dust sealing, moisture sealing, vignetting, speed, weight, etc., so I did not have any confusion on these points. It merely seemed like a "waste" of the L lens to use it on an APC sensor body like my T1i, since the "system" resolution of both the lens and sensor as compared by photozone shows the 15-85 to be a bit better at the "best" choice of focal length and aperture from each of the 2 lenses. This was a surprsing comparison to me, since I assumed the L was far better in resolution.
I am still puzzled by the comment that these resolutions are not the key to selecting a sharp lens since the printed result will not reveal this resolution difference. I understand that even a big 11 by 14 print would not allow anywhere near the number of line pairs (2500 or so) to be visible, but certainly this resolution must direcly measure how well or poorly the detail in the original scene is captured. Cropping and pixel peeping certainly would reveal the difference, as would a print of an enlarged crop. Isn't this true? And thus the MTF/resoltution must be the key to knowing how well the lens resolves detail, even if it is not visible under some printing or other circumstances.
Thanks again for guidng me here.
Larry
My practical reason for posing this question originally was the basic confusion I had as to whether buying the 24-105L would gain me anything at all in resolution on my T1i when compared to the option of buying the new 15-85.
I totally understand that these are 2 entirely different lenses, and there are good reasons other than resolution to prefer one to the other. Among these differences are range of zoom, build quality, dust sealing, moisture sealing, vignetting, speed, weight, etc., so I did not have any confusion on these points. It merely seemed like a "waste" of the L lens to use it on an APC sensor body like my T1i, since the "system" resolution of both the lens and sensor as compared by photozone shows the 15-85 to be a bit better at the "best" choice of focal length and aperture from each of the 2 lenses. This was a surprsing comparison to me, since I assumed the L was far better in resolution.
I am still puzzled by the comment that these resolutions are not the key to selecting a sharp lens since the printed result will not reveal this resolution difference. I understand that even a big 11 by 14 print would not allow anywhere near the number of line pairs (2500 or so) to be visible, but certainly this resolution must direcly measure how well or poorly the detail in the original scene is captured. Cropping and pixel peeping certainly would reveal the difference, as would a print of an enlarged crop. Isn't this true? And thus the MTF/resoltution must be the key to knowing how well the lens resolves detail, even if it is not visible under some printing or other circumstances.
Thanks again for guidng me here.
Larry
