Why no 28-300/18-200 lenses with lower f-stop?

On 2011-07-18 15:26:32 -0700, me said:

On 18 Jul 2011 21:00:07 GMT, Chris Malcolm
wrote:

Of course it is. While the quality of even a 10x zoom may not be equal
to that a a top notch prime, It can be quite useful when weight and bulk
are issues.

And don't forget aperture. While no wide ranging zoom is much good at
its widest aperture, the best modern ones are pretty good for most of
their range at f8. Good enough that it would take a critical pixel
level comparison to distinguish image quality from that of a prime of
equivalent focal length at f8. Which is good enough that you'd see no
difference in the highest quality A4 print, and in some cases you'd
find it hard to see a difference in an A3 print.


Also lest not forget it is not just sharpness which is comprimised.
Distortion can be not trivial either. That said I've recently acquires
the Nikon 18-200 VR2 and it serves it's purpose. However it does help
to shoot raw and be able to correct for lens distortion in the
conversion process when needed.

I have found the 18-200mm VRII to be a very useful general purpose lens
with one caveat, one always needs to remember that it is a compromise
lens with very good potential if used correctly, so I work accordingly.
It is my work horse , walk-around lens. I usually have my bag loaded
with 11-16mm f/2.8, 35mm f/2.0, and 70-300mm VR near at hand, but there
are times I don't care to lug the bag. If I anticipate a need for a
different lens, I will just add it to a pocket in my Columbia vest. For
the most part I will just grab the D300s + 18-200mm and go.

Many of my recent Yosemite shots were taken with that combo. This
Valley shot, using the 18-200mm was shot at 32mm @ f/8.
http://homepage.mac.com/lco/filechute/DNC_9246fw.jpg

--
Regards,

Savageduck

me wrote:
On 18 Jul 2011 21:00:07 GMT, Chris Malcolm
wrote:

Of course it is. While the quality of even a 10x zoom may not be equal
to that a a top notch prime, It can be quite useful when weight and bulk
are issues.

And don't forget aperture. While no wide ranging zoom is much good at
its widest aperture, the best modern ones are pretty good for most of
their range at f8. Good enough that it would take a critical pixel
level comparison to distinguish image quality from that of a prime of
equivalent focal length at f8. Which is good enough that you'd see no
difference in the highest quality A4 print, and in some cases you'd
find it hard to see a difference in an A3 print.

Also lest not forget it is not just sharpness which is comprimised.
Distortion can be not trivial either. That said I've recently acquires
the Nikon 18-200 VR2 and it serves it's purpose. However it does help
to shoot raw and be able to correct for lens distortion in the
conversion process when needed.

Geometric distortions (barrel, pincushion, moustache, etc) don't get
any benefit from being applied at the RAW conversion stage. They apply
just as well to high quality jpegs provided no cropping or other
alterations of image geometry have been introduced. You're quite right
that generally speaking you can expect more geometric distortions from
zooms than primes, and more from the wider ranging zooms. Although
once again there is usually in any good zoom at least one sweet focal
length where there is no more geometric distortion than in a prime of
that focal length.

Where corrections of chromatic aberrations are concerned the extra
colour information available at the raw level would help.

--
Chris Malcolm

Savageduck wrote:
On 2011-07-18 15:26:32 -0700, me said:

On 18 Jul 2011 21:00:07 GMT, Chris Malcolm
wrote:

Of course it is. While the quality of even a 10x zoom may not be equal
to that a a top notch prime, It can be quite useful when weight and bulk
are issues.

And don't forget aperture. While no wide ranging zoom is much good at
its widest aperture, the best modern ones are pretty good for most of
their range at f8. Good enough that it would take a critical pixel
level comparison to distinguish image quality from that of a prime of
equivalent focal length at f8. Which is good enough that you'd see no
difference in the highest quality A4 print, and in some cases you'd
find it hard to see a difference in an A3 print.

Also lest not forget it is not just sharpness which is comprimised.
Distortion can be not trivial either. That said I've recently acquires
the Nikon 18-200 VR2 and it serves it's purpose. However it does help
to shoot raw and be able to correct for lens distortion in the
conversion process when needed.

I have found the 18-200mm VRII to be a very useful general purpose lens
with one caveat, one always needs to remember that it is a compromise
lens with very good potential if used correctly, so I work accordingly.
It is my work horse , walk-around lens. I usually have my bag loaded
with 11-16mm f/2.8, 35mm f/2.0, and 70-300mm VR near at hand, but there
are times I don't care to lug the bag. If I anticipate a need for a
different lens, I will just add it to a pocket in my Columbia vest. For
the most part I will just grab the D300s + 18-200mm and go.

My single general purpose carry around outdoor lens is my 18-250mm. If
I avoid the two extreme ends of the range and stick to f8 it's capable
of very good results. If I have to raise ISO above 800 the noise
reduction image quality losses are generally speaking larger than the
losses in image quality introduced by opening it to f6.3, and in some
cases to f5.6.

But in cities and architectural interiors I so often find that 18mm
(on a APS-C sized sensor) is not wide enough that I rarely just carry
that one lens. I usually extend its range with an 8-16mm, and because
it's so small and light compared to those two zooms I usually also
bung in an f1.4 50mm for low light or narrow depth of field.

--
Chris Malcolm

On Tue, 19 Jul 2011 17:54:20 -0500, John Turco wrote:
: Michael Benveniste wrote:
:
: On 7/14/2011 10:02 AM, Bruce wrote:
:
: I agree, it is the worst feature of the 75-150mm. However, it doesn't
: affect the Nikon 70-210mm f/4 Series E, when it might be expected to.
: I have a well-used AI converted 80-200mm f/4.5 Nikkor and the zoom
: creep is nowhere near as bad as the 75-150mm E, plus the overall build
: quality is in a different league.
:
: The 70-210mm suffers from zoom creep as well, but why Nikon chose to
: use the felt strip approach on some lenses and not on others I can't
: even begin to speculate. The point is that Nikon _did_ use this
: approach for both Nikkors and non-Nikkors, and the competing but
: similar portrait zooms from did not.
:
: I can't speak to the non-AI copy you claim to have, but it's irrelevant.
: Nikon totally redesigned the lens in 1977, including a new optical
: formula, and used felt strips in the new design.
:
: I have a long history of contact with two Nikon designers, one going
: back to the 1970s, who have been clear as to how the Series E project
: was managed.
:
: Ah yes, the "appeal to anonymous authority" fallacy. How very typical.
:
: Let us not forget that the whole point of Series E was to produce
: optically good but inexpensive lenses. Kino Precision was never
: a cheap manufacturer, and not a company with which Nikon has had
: extensive dealings in any case.
:
: Kino did provably produce lenses for other budget manufacturers,
: including Vivitar. Whether Nikon had dealings or not merely assumes
: your conclusion, and like Tokina, Kino was founded by former Nikon
: engineers.
:
: To quote one Tony Polson from rec.photo.equipment.35mm, "The lens
: was made for Nikon by Kino Precision of Japan, who also made some
: outstanding optics for Vivitar, as well as their own Kiron range."
:
: edited for brevity
:
: "Bruce" and "Tony Polson" are the same poster!

Yes!! You apprehended Michael's point. Well done!

Bob

"Robert Coe" wrote in message
...
On Tue, 12 Jul 2011 15:12:23 +0100, Bruce wrote:
[]
: An 11X zoom is a choice only for undiscerning camera owners who don't
: care about image quality - people who bought interchangeable-lens
: cameras (why?) but are just too darn lazy to change lenses.

Such as, perhaps, newspaper photographers? Differences in image quality
are
usually undiscernible in a newspaper, and not having to change lenses
(or
carry two or three cameras) may be important. (That said, I may be all
wet.
When I'm covering an event, I usually notice what kind of cameras others
are
using, but rarely get a good look at their lenses.)

Bob

... and situations where changing lenses may be difficult, or expose the
sensor to dust or moisture. Obviously outside the experience of
Bruce/Tony.

David

Mike wrote:

That is pure math, a 300mm f:2.

And only works when you're not using a tele lens (which is
shorter than it's focal length).

Nikon did make a special order 300/2
that used a 160mm filter, so about 6% bigger in diameter than math to
compensate for light loss.

I doubt that that was for light loss. After all, f/stop is
geometry and bokeh, and t-stop is light passage (and can be
quite different --- just introduce an ND filter into the system
and see how the t-stop rises while the f/stop stays where it is.
Another example are mirror lenses.)

-Wolfgang