In the past maxiumum f5.6 was tolerated for a zoom lens with very few exceptions that was when ISO 400 film was considered high ISO.
Today with higher and cleaner ISO becoming available we are seeing canon launching two f7.1 zooms
while 100-500f4.5-7.1 is a very reasonable offering 24-105f4-7.1 seems odd.
Well, it's the fight for the low-end market ...
Chief Editor - opticallimits.com
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The 100-500 doesn't look low end... It's an L lens probably with the (future) price tag matching that of the EF 100-400.
It indeed looks like a EF 100-400mm f4.5-5.6 L IS USM II which focal length range has been extended to 500mm, without the aperture also being extended (to contain costs and weight?).
The 100-400mm has a max aperture of f5.6.
f5.6 / 400 x 500 = f7... Makes sense in the Canon universe. If only the $1400 Nikkor 200-500mm f5.6 did not exist...
Wasn't f/5.6 the limit for phase AF in most (D)SLRs? If you wanted AF, you generally had to stick to that. Does imaging sensor based AF systems have a similar limitation? I'm not up to speed on those.
<a class="bbc_url" href="http://snowporing.deviantart.com/">dA</a> Canon 7D2, 7D, 5D2, 600D, 450D, 300D IR modified, 1D, EF-S 10-18, 15-85, EF 35/2, 85/1.8, 135/2, 70-300L, 100-400L, MP-E65, Zeiss 2/50, Sigma 150 macro, 120-300/2.8, Samyang 8mm fisheye, Olympus E-P1, Panasonic 20/1.7, Sony HX9V, Fuji X100.