Dawei Ye wrote:
The 17-55 IS is actually the crop equivalent to the 24-105L, not the 15-85. The 15-85 is an entirely different lens.
f/2.8 crop = f/4 FF because:
- FF has 1 stop DOF advantage when framing equalised
- FF is 1 stop cleaner high ISO, to compensate for the light loss from f/2.8 to f/4
88mm (55mm X 1.6) is closer FOV to 105 than 136mm (85mm X1.6)
YEath, but it\'s the wide end that matters (you can always crop an 85 mm to 105 without much loss of detail.
15 * 1.6 = 24, 17 * 1.6 = 27
Those 3 mm on the wide end make much more of a difference.
Jan 19, 2012 at 11:04 PM
Previous versions of tr1957's message #10263627 « Canon 24-105 vs. 15-85 »
