Why are the new DX lenses so slow?

I suppose that Canon and Nikon are in business to make money. When they
design lenses that cost more than a new SUV, they tend to be slow sellers.


"Steve" wrote in message
...
Nikon and Canon both. I have lenses for my old F100 that are faster
than what both companies are offering. I mean f2.8 or less and a constant
speed through the zoom range. Does anybody have information about why
these digital lenses are coming out with such high and variable f-stops?

Tired of noisy pictures,


Steve

"Floyd L. Davidson" wrote in message ...
"DP" wrote:
"Jeremy Nixon" wrote:
Steve wrote:

Nikon and Canon both. I have lenses for my old F100 that are faster than
what both companies are offering. I mean f2.8 or less and a constant speed
through the zoom range. Does anybody have information about why these
digital lenses are coming out with such high and variable f-stops?

Probably for size/weight/price reasons - there are some fast
constant-aperture zooms either designed for the smaller format,
or for the larger, but useable on the smaller.

As for the variable f-stops, I would assume it's because as the focal
length changes that automatically changes what the f-stop is. The same-sized
hole is a different f-stop for 50 mm than it is for, say, 125 mm.

True. But see below...

I was never a fan of zooms even in my film days, so I'm not that familiar
with them. You say that there are zooms where the widest f-stop is not
variable as the lens is zoomed out? Correct me if I'm wrong, but I think
that means the manufacturer was simply not telling you the truth about that
lens and not letting you know that the widest aperature opening has a
different f value based on how far out the lens is zoomed.

No. If you set the aperture to a given stop and look into the
front at the diaphragm blades as you zoom the lens, you will see
that the blades move to to keep the aperture constant (a lens
that has the diaphragm wide open at the longest FL will close
the diaphragm some as it is zoomed to the shortest FL). This
is true only for constant-aperture zooms...

There is some variation, but it is relatively small. They are not
being dishonest. A 1/3rd stop or less variation is not worth the
distinction, but a 1/2 stop or more variation certainly is.

Due to manufacturing tolerances and illumination unevenness,
there can be slight effective-stop changes, but otherwise, the
stop really does not change...

However, like all things in lense design it is a compromise. It
is possible to produce, at a lower cost, a sharper lense if it
has a variable aperture over the focal length range. A constant
maximum aperture is possible, but it either produces a less
sharp lense or costs significantly more.

Yes, but there have been exceptions. The Nikkor 75-150mm
f3.5 E was an excellent zoom with a constant aperture and
low price. The 70-210 f4 E and 36-72mm f3.5 E Nikkors
were other examples.

It is not uncommon to target a design for low cost production,
and that is often best accomplished by allowing the maximum
aperture to vary.

True.

It is also common to target a different design for "best
performance at whatever it costs", and that will often have a
wider maximum aperture that is constant (relatively) across the
focal range. But the lense will appeal only to those who can
justify the money spent for the best possible lenses.
--
Floyd L. Davidson http://www.apaflo.com/floyd_davidson
Ukpeagvik (Barrow, Alaska)

Also true - and for those who are willing to lug the monsters
around... Too bad there aren't more good f3.5 or f4 constant-
aperture zooms, so one doesn't need to choose between
f2.8 or f5.6 "wide"-open at the long end. F3.5-4.5 isn't a
bad compromise, though, I guess (if more were truely high
quality - I've still seen nothing in the current Nikon line other
than the constant-aperture f2.8 zooms [which are excellent!]
to equal the old MF 35-105mm f3.5-4.5 [selected sample
only, though!]).
--
David Ruether


http://www.ferrario.com/ruether

In article cTaUg.4030$pN.3033@trndny07,
David Ruether wrote:

Too bad there aren't more good f3.5 or f4 constant-
aperture zooms, so one doesn't need to choose between
f2.8 or f5.6 "wide"-open at the long end.

I guess you just need to have chosen the right system :-)

I can get a (great) 12-24/f4 and a (good) 16-45/f4 today,
with a 60-250/f4 announced (but not available this year).
I'm more interested in the 16-50/f2.8 & 50-135/f2.8, though.

"David Ruether" wrote:
"Floyd L. Davidson" wrote in message ...

No. If you set the aperture to a given stop and look into the
front at the diaphragm blades as you zoom the lens, you will see
that the blades move to to keep the aperture constant (a lens
that has the diaphragm wide open at the longest FL will close
the diaphragm some as it is zoomed to the shortest FL). This
is true only for constant-aperture zooms...

I've never noticed any lense that did that.

There is some variation, but it is relatively small. They are not
being dishonest. A 1/3rd stop or less variation is not worth the
distinction, but a 1/2 stop or more variation certainly is.

Due to manufacturing tolerances and illumination unevenness,
there can be slight effective-stop changes, but otherwise, the
stop really does not change...

It does. How much depends on the design of the lense. If the
designer allows much change, they label it as variable. If the
change is (as I stated originally) small, they call it constant.

However, like all things in lense design it is a compromise. It
is possible to produce, at a lower cost, a sharper lense if it
has a variable aperture over the focal length range. A constant
maximum aperture is possible, but it either produces a less
sharp lense or costs significantly more.

Yes, but there have been exceptions. The Nikkor 75-150mm
f3.5 E was an excellent zoom with a constant aperture and
low price. The 70-210 f4 E and 36-72mm f3.5 E Nikkors
were other examples.

The Nikkor 75-150mm f/3.5 E, for example, does not change the
aperture as it is zoomed.

Regardless of the fact that those are low cost constant maximum
aperture lenses, that does *not* negate the statement you are
replying to. If they had been designed to have a variable
maximum aperture they probably would have been even less
expensive to manufacture. The problem then would have been
marketing, because Nikon wanted to maintain the appearance of
top quality.

--
Floyd L. Davidson http://www.apaflo.com/floyd_davidson
Ukpeagvik (Barrow, Alaska)

In article ,
(John Francis) wrote:

In article cTaUg.4030$pN.3033@trndny07,
David Ruether wrote:

Too bad there aren't more good f3.5 or f4 constant-
aperture zooms, so one doesn't need to choose between
f2.8 or f5.6 "wide"-open at the long end.

I guess you just need to have chosen the right system :-)

I can get a (great) 12-24/f4 and a (good) 16-45/f4 today,
with a 60-250/f4 announced (but not available this year).
I'm more interested in the 16-50/f2.8 & 50-135/f2.8, though.

Nikon has a good system already available.....

12-24/4, 17-55/2.8, 10.5/2.8 fisheye...more to come as well....

JR

Steve wrote:
Nikon and Canon both. I have lenses for my old F100 that are faster than
what both companies are offering. I mean f2.8 or less and a constant speed
through the zoom range. Does anybody have information about why these
digital lenses are coming out with such high and variable f-stops?
Tired of noisy pictures

Canon has many new large aperture lenses:
Canon 17-55/2.8 IS
Canon 50/1.2
Canon 85/1.2

http://digitcamera.tripod.com/#slr

"Rita Ä Berkowitz" ritaberk2O04 @aol.com wrote in message
...

There's just a slight correction needed here. This should be the
Tokina
12-24, then all Nikon 17-35, 28-70, 70-200 and an optional 10.5.
Sadly I
must say that the Nikon 12-24 is severely lacking in image and build
quality
and the Tokina is king in this arena, plus it's a lot less
expensive. The
17-55 is mediocre and should not be considered over the 17-35 and
28-70
combination. If Nikon continues its current trend towards consumer
grade DX
lenses we will all be screwed.

I just realized something..."Rita" is on prescription drugs.

And I'm not entirely sure it's really prescription either...

:-)

Michael Schnell wrote:
Supposedly the D80 will make the D200 a more "prof"-choice and less
interesting for discounters.

But regarding the experiences we had with the D100 and D70, I'm glad we
have a D200 and would rather buy another D200 than a D80 for backup.

Michael,
What would these experiences be? (Out of curiosity).
Cheers.

"Steve" wrote in message
...
Nikon and Canon both. I have lenses for my old F100 that are faster
than what both companies are offering. I mean f2.8 or less and a constant
speed through the zoom range. Does anybody have information about why
these digital lenses are coming out with such high and variable f-stops?

Tired of noisy pictures,

Because they are inexpensive?

Rita Ä Berkowitz wrote:

LOL! Bill, look at the reviews and side-by-side images produced by these
lenses and you will see that the Tokina is the best out of the bunch out of
all the 12-24 produced. I know this fact is hard to swallow; I had the
same
problem believing it. The proof is out there.


Is this proof?
http://www.nikonians.org/nikon/nikko...berration.html