I'm asking for a 50 - 135 F2.0 DX VR AFS.
I'm not asking for a 120-300mm F2.8. I know how big a 135mm F2.0
needs to be. I also know that a 200mm F2.0 needs to be about the
size of the 300mm F2.8 and I'm not asking for that either.
An f/2 zoom needs to be considerably larger than an f/2 prime.
Also, the Nikon 70-200 F2.8 VR is about the same size as the
300mm F4.0 and the Sigma 100-300 F4.0.
You are proving my point: an f/2.8 zoom with a max focal
length of 200mm can't be smaller than a 300mm prime
with a max aperture two f-stops smaller or a zoom up to
300mm again with a max aperture of only f/4. If you
want a zoom that tops at 300mm and it's a constant
f/2.8, it can't be smaller than the Sigma 120-300, which
is considerably larger and heavier than the 100-300 (not
to mention pricier...)
The lens I am asking for will be no bigger than the current
70-200.
No way. You want it to be f/2, it would be prohibitevely
huge and prohibitevely expensive.
Aperture is like speed: to go from 50 to 60 mph it only takes
a 20% increase in energy while to go from 300 mph to 310
it takes a HUGE one. Until you're talking f/4, you're still in
the 50mph zone, when you want to go from 2.8 to 2.0,
it becomes an almost impossible challenge. In fact, no one
has ever done an f/2.0 zoom with that kind of excursion.
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'Everything should be made as
simple as possible, but no simpler.'
(Albert Einstein)
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