Are IS lenses doomed ?

Rebecca Ore wrote:
In article ,
"Mark²" mjmorgan(lowest even number wrote:

Rebecca Ore wrote:
In article ,
"Mark²" mjmorgan(lowest even number wrote:

Rebecca Ore wrote:
In article ,
"Neil Harrington" wrote:

Not in their actual focal lengths, no. But 35mm equivalencies are
always given for them, and typically these are zooms of 35-105mm
(equivalent) or thereabouts.

Again, for people who don't know squat about lenses.

Have you always been such a -----?

Especially on Usenet after the first time someone didn't listen to
what I said and asked for someone with a dick to answer his
question.

Ah. OK. Well...at least you know you're being a -----. That's a
start...

Women know they've won the argument when they get called bitch or are
accused of arguing like a man.

If you really believe that, then there is little hope for you.

--
Images (Plus Snaps & Grabs) by Mark² at:
www.pbase.com/markuson

Alan Browne wrote:
King Sardon wrote:
On Sat, 27 Jan 2007 15:39:37 -0500, Alan Browne
wrote:


The metric system uses fundamental things in nature to divide it up.
The Kelvin scale uses the same dimension as the centigrade scale
which in turn has its origin (0) at a very human famillar point of
where water freezes and a 100 where water boils (at sea level),
another very "human" point. From there, a gram is 1 cm^3 of water
(original def.). The meter comes from sub-dividing the distance
between the equator and either pole (10,000,000 m) (original def).


There is absolutely no need for units to be "human". The main benefit
of standardized units is that everybody uses the same unit and
everybody knows what it means. How it was originally defined is just
trivia.

It may just be trivia, but as the "trivia" was defined by people, it is
important indeed.


IMHO there is nothing scientifically fundamental about the distance
between the equator and the pole.

The equator to pole reference was a reasonable one at the time that the
meter was first proposed. You ended up with a meter that was similar to
the yard and units that are reasonable for navigation over long
distances. The nautical mile was similarly derived (1 minute of
latitiude; since replaced with 1 NM = 1852 meters)

You state how "human" the centigrade (actually Celsius) scale is. How
about the Fahrenheit scale, then? Its lowest temp was originally
considered to be the lowest attainable temperature (mixture of salt
and ice) and 100 on that scale was supposed to be the body temperature
of a human. They were only out by 1.4 deg.

Actually, Dr. Farenheit intended for 96°F to be the human core temp (why
not 100, I have no idea).

The F scale is more useful for room temp and weather measurements, but
C is still preferred for (most) all temp measurements just because it
is the standard.

More Useful? How so? Centigrade is a perfectly "useful" way to set the
temperature. My daytime house temp when I'm away is 16° and it is set
to 20°C in the evening...

As for usefulness, either method of temperature measurement is useful.
But which is more accurate?

In 1742, Celsius proposed temperature measurement should be changed and
he proposed the change should be that intervals of temperature be
divided into 100 divisions using the span between boiling water and
freezing water. I haven't found data that referenced what the barometric
pressure was at the time water was boiled nor have I found data that
referenced how pure the water was that he used for his experiments. If
indeed he used new data as opposed to using what may have been
established data. I just recall both being taken at sea level.

In 1710, Fahrenheit proposed temperature divisions be made using three
fixed temperature data points; average human temperature, freezing point
of water, and an ice-salt mixture. I think he used the melting point of
the ice-salt mixture. To my way of thinking, using divisions between
established fixed data points would be more accurate than using a
hypothetical division of 100 units between two data points.



Americans are just so accustomed to imperial units as to set a huge
reistance to change.

Change, for the sake of change is in itself not practical. Why change
what ain't broke?

But the change is not that hard; and the benefits
of common units pay for themselves over time.

Common units were already established where common units were being
used. Costs incurred by changes did not affect those who had accepted
Celsius temperature and didn't need to change. However, it's my guess
that if a change in temperature divisions were proposed that required
the whole world to made necessary changes there would be an outcry to
not fix what is considered the standard so long as it ain't broke.



(K is usually used only for cryogenics and the overly fussy despite it
being the SI standard for temp measurements. If you read the
scientific literature, you come across temps like 373 K and 423 K.
That means they were working in C but the journal made them convert
temps to K.)

That depends entirely on the domain of application. When calculating
"how much heat" is contained in something, then K is more useful. When
detailing "what is the temperature" of something, then C is more useful
for things that happen in everyday temperatures.

On Sun, 28 Jan 2007 19:01:03 +0000, Prometheus
wrote:

In article , Bill Funk
writes
On Fri, 26 Jan 2007 14:03:34 -0500, "Neil Harrington"
wrote:

I find this amusing.
You know what "crop factor" means,

I have no idea what it might mean. I have asked repeatedly, How can you crop
1.5 of anything? No one yet has been able to answer this simple question.

OK, here it is again. Pay attention...
The crop factor is a multiplier you apply top the focal length of a
lens based on how much the sensor crops out of the image at the sensor
plane based on a 35mm frame size.

In simple terms, you crop something you have not got to get what you
have got, and then pretend that you have a longer lens than you have.

I can not understand how some people do not understand the basic
concept of a crop.
I can only think it must be because they have some investment in
disliking anything they don't want to hear.
If you do not understand the fact that the image the sensor sees is a
crop of the image in the image circle, I'm afraid I can't help you.
That you refuse to understand that what a APS-C sensor sees is a crop
of what a 35mm frame-size sensor would see in the same image circle is
truly amazing, even after it's been explained, is inexplicable.

Does this help?

Nope, it's nonsense.

To you, obviously.

--
California's Assembly prepared
Monday to move the state's
primary up to February. An early
California primary has unique
advantages. It gives each candidate
the chance to spend all their money
to finish third behind Gary Coleman
and a porn star.

On Sun, 28 Jan 2007 12:19:27 -0500, "Neil Harrington"
wrote:


"Bill Funk" wrote in message
.. .
On Fri, 26 Jan 2007 14:12:37 -0500, "Neil Harrington"
wrote:


"Bill Funk" wrote in message
...
On Fri, 26 Jan 2007 00:07:25 +0000, Prometheus
wrote:

In article , Bill Funk
writes
On Thu, 25 Jan 2007 07:48:35 -0500, "Neil Harrington"
wrote:

Nothing is cropped. To crop means to remove part(s) of an existing
image.

What do you think is formed at the sensor plane?

The image on the sensor is the full image, not a crop of it, unless you
want to argue that a 35mm frame being less that a 4x5in frame it is also
a crop.

And, once again, someone who wants to bring LF into a 35mm thread.
Get over it.

It's not a 35mm thread, and this isn't a 35mm newsgroup. LF is no more off
topic than 35mm is.

Neil

Correct me if I'm wrong:
This is a discussion of how to describe the difference in the coverage
of the field of view between 35mm frame size and APS-C frame size.
No?

More or less. There are other frame sizes in DSLRs besides the so-called
"APS-C" frame size, which is not really APS-C size or any other APS size. So
the lens conversion factors are useful in other sizes as well. It would be
good to get away from the "APS" misnomers altogether. At least one user here
has already called Canon's 1.3x bodies "APS-H" size, which is getting really
silly about it. It's not only wrong, but the APS H frame is 16:9 aspect
ratio, which of course the Canon in question is not -- adding even more
confusion to the matter.

Ah, I see.
You want to nit-pick your way out of it, by saying hat APS-C isn't a
valid term, even though it's the onme the industry uses.

I've used the term "APS-C" in this connection myself, I'm sorry to say. I
don't do it anymore.

And here we go, off on another ride to see what you want to rename an
industry term - APS-C.


If so, how does anything other than those two frame sizes enter into
the discussion?

Once you raise the issue of what "crop" means, you cannot reasonably limit
the discussion to those two (or three, or four, or five) frame sizes.

Sure I can. What can't I, when I specifically tell you want I'm
talking about?

Neil


--
California's Assembly prepared
Monday to move the state's
primary up to February. An early
California primary has unique
advantages. It gives each candidate
the chance to spend all their money
to finish third behind Gary Coleman
and a porn star.

On Sun, 28 Jan 2007 19:09:32 +0000, Prometheus
wrote:

In article , Bill Funk
writes
On Fri, 26 Jan 2007 14:12:37 -0500, "Neil Harrington"
wrote:


"Bill Funk" wrote in message
...
On Fri, 26 Jan 2007 00:07:25 +0000, Prometheus
wrote:

In article , Bill Funk
writes
On Thu, 25 Jan 2007 07:48:35 -0500, "Neil Harrington"
wrote:

Nothing is cropped. To crop means to remove part(s) of an existing
image.

What do you think is formed at the sensor plane?

The image on the sensor is the full image, not a crop of it, unless you
want to argue that a 35mm frame being less that a 4x5in frame it is also
a crop.

And, once again, someone who wants to bring LF into a 35mm thread.
Get over it.

It's not a 35mm thread, and this isn't a 35mm newsgroup. LF is no more off
topic than 35mm is.

Neil

Correct me if I'm wrong:
This is a discussion of how to describe the difference in the coverage
of the field of view between 35mm frame size and APS-C frame size.
No?

The thread was about IS lenses.

Would you be happier if I changed the subject name?
The thread we are currently on is indeed about the difference in frame
coverage; there are very often different threads within named subjects
on Usenet.

If so, how does anything other than those two frame sizes enter into
the discussion?

It has progressed to discussing the effect on lenses of different images
sizes.*

No, it has progressed to talking about the amount of the image formed
on the image plane that is captured by different sized sensors when
placed on that image plane.

* There is, of course, none. The image occurs after the light has past
through the lens and can have no effect on the lens.

Of course; thus the need to determine how to adjust the nomenclature
of the lens' marked FL to account for the differing AOF the different
sensor sizes subtend.

--
California's Assembly prepared
Monday to move the state's
primary up to February. An early
California primary has unique
advantages. It gives each candidate
the chance to spend all their money
to finish third behind Gary Coleman
and a porn star.

On Sun, 28 Jan 2007 13:29:53 -0500, "Neil Harrington"
wrote:


"Bill Funk" wrote in message
.. .
On Fri, 26 Jan 2007 14:21:16 -0500, "Neil Harrington"
wrote:


"Bill Funk" wrote in message
...
On Thu, 25 Jan 2007 22:02:18 -0500, "Neil Harrington"
wrote:


"Bill Funk" wrote in message
om...
On Thu, 25 Jan 2007 07:48:35 -0500, "Neil Harrington"
wrote:

Nothing is cropped. To crop means to remove part(s) of an existing
image.

What do you think is formed at the sensor plane?

An image, *on the sensor*. No other image is being formed anywhere, so
"that's all there is, there ain't no more."

And here you prove to what lengths you will go to attempt to continue
your inane agenda.
The image formed at the sensor plane is most definitely *NOT* the
image on the sensor,

Of course it is. Where else is an image formed?

At the imager plane.
If you can do so, please demonstrate the difference between a sensor
and an image plane.

The "difference"? They are entirely different. An image plane is a
theoretical plane of best focus for object(s) at a certain distance. A
sensor is a physical component which may be placed *at* the image plane to
receive the image.

The difference is that the sensor is a *part* of the image plane.
In other words, it is a crop, if you will, of the image plane.


Try real hard, using whatever graphic program you like.

Very easy, took only the few lines above.


The post this demonstration.
If you do so, notice that the sensor does not completely cover the
image formed at the image plane.

It NEVER does, except in the case of a full-hemisphere fisheye.

I note that you neatly cropped out the part where I specifically said
I am excluding fisheye lenses:
"(I am excluding fisheye lenses)"
Don't try to be dishonest.

[ . . . ]

Which you don't.

Sure I do. The sensor and the image are a perfect fit, and cannot be
otherwise.

So the image circle is actualy a rectangle?

It may very well be in the way you think of these things, but in the real
world circles are never rectangular, and rectangles are never circular.

Read it again: I said the sensor and the IMAGE are a perfect fit. Not the
sensor and the image circle.

If the image circle is where the image resides, and the image circle
is defined by the image, it must be circular.
Thus, a rectangular sensor and the image circle can never be a perfect
fit.

AGAIN (for the 30th time or so), all lenses except full-hemisphere fisheyes
produce image circles larger than the film or sensor used to capture the
image. You evidently believe that means all those pictures, about 99.999997%
of all the photographs ever taken anywhere in the world, are "cropped." They
are not.

If what the sensor sees is less than the image circle (and it is), why
is what the sensor sees not a crop of the image circle?

Cropping is something you do to an actual, existing image -- not an Image
That Might Have Been If Only Things Were Different.

The image exists within the image circle. There's no way around that.
So the image within the image circle is not "Image That Might Have
Been If Only Things Were Different." It's really there.
So the sensor does indeed crop from an existing image.

Neil


--
California's Assembly prepared
Monday to move the state's
primary up to February. An early
California primary has unique
advantages. It gives each candidate
the chance to spend all their money
to finish third behind Gary Coleman
and a porn star.

On Sun, 28 Jan 2007 21:54:13 GMT, Bryan Olson
wrote:

John Francis wrote:
[...]
A quick question: without calculation, which do you think would be heavier?
A substance with a density of 20 grams per litre, or one with a density
of 20 ounces per cubic foot?

The densities are too close to do without calculation.
Fortunately it's now just a matter of typing

20 grams per litre in ounces per cubic foot

into Google.

That will tell you which is denser, not which is heavier.
Consider the question, "Which is heavier, a pound of feathers, or a
pound of lead?"
They are both of equal weight, but the density is different.

--
California's Assembly prepared
Monday to move the state's
primary up to February. An early
California primary has unique
advantages. It gives each candidate
the chance to spend all their money
to finish third behind Gary Coleman
and a porn star.

In article ,
"Mark²" mjmorgan(lowest even number wrote:

Women know they've won the argument when they get called bitch or are
accused of arguing like a man.

If you really believe that, then there is little hope for you.

I'm not the only woman who's noticed this, either. Some guys feel like
their balls would fall off if they accepted advice from a woman or lost
an argument to one.

It's not true of all men.

Rebecca Ore wrote:
In article ,
"Mark²" mjmorgan(lowest even number wrote:

Women know they've won the argument when they get called bitch or
are accused of arguing like a man.

If you really believe that, then there is little hope for you.

I'm not the only woman who's noticed this, either. Some guys feel
like their balls would fall off if they accepted advice from a woman
or lost an argument to one.

It's not true of all men.

You haven't offered advice. You've only offered extremely arrogant,
tunnel-visioned insults.
As to losing an argument...you never really participated in the discussion.
You merely launched into mostly unrelated statements eluding to the supposed
ignorance of 35mm users, and the superiority of knoweldge that supposedly
goes hand in hand with MF and LF users.

For what it's worth... there are plenty of idiots in both camps. The
biggest idiot photographer I know used MF until about a year ago. He now
shoots with a 35mm-based DSLR...and guess what? -He's still an idiot.

Idiocy knows no format boundary. It's just that when one format is
prohibitively expensive and less ocnvenient, it tends to attract a larger
proportion of serious users. You'd do well to avoid your tendency to
generalize. -While you threw in a nifty "It's not true of all men" you do
so only after operating your your generalized assumptions about "men."

Think what you will...but I'd recommend abandoning the man-hater's club, and
re-join the team of man and woman.

Do you have a web-site with samples of your work?
I make no claims of mastery, but I'd love to be witness to yours...


--
Images (Plus Snaps & Grabs) by Mark² at:
www.pbase.com/markuson

In article , nick c
writes
David Littlewood wrote:
In article , nick c
writes

Units of measurement are theoretical. A standard unit of measurement
is whatever is accepted by international standardization agreement.
Indeed.

It would be interesting to learn what units of measurement are used
by alien space travelers, if indeed there are such things as alien
space travelers. In the meantime, nations in this world still accept
the standard passing of time as 60 seconds equals one minute and 60
minutes equal one hour though I suspect horologists are working to
find a way to metrically change the way time is measured. Thus
rendering all the standard time pieces presently used throughout the


The definition of the second (the SI unit of time) has changed over
the years - at least two definitions in astronomical terms in the
1950s. In 1964 the definition was changed to be the duration of
9,192,631,770 periods of the radiation corresponding to the transition
between two hyperfine levels (F=4, M=0 and F=3, M=0) of the ground
state of the caesium 133 atom.
David


That should read, the ground state of the caesium 133 atom ..... at 0
Kelvin.

Indeed; this was a later (1997) clarification.

Thereby using agreed upon theory to define time interval but not the
common state of time of day. My posted concern was related to defining
what a metric day would be as made up from the passing of the time it
takes for the earth to make one revolution, which is not 24 hours but
25 hours. Using 25 hours, each hour would then (using metric units
divisible by 10) be divided into 100 metric minutes and each metric
minute would then be 100 metric seconds. Thus a day would not consist
of 86,400 seconds but 250,000 metric seconds. When pressed to go
metric, commonly used time pieces used throughout the world would
become obsolete. The common mechanical clock/wris****ch keeps time
using the traditionally accepted 60 sec x 60 min x 24 hr/day = 86,400
sec/day. Using metric time would be 100 metric sec. x 100 metric min.
x 25 hr/day = 250,000 metric seconds/day. The hour would change from
one hour being composed of 60 minutes to one metric hour being composed
of 57.6 minutes. The common clock/watch would be short 2.4 minutes/day.
Discounting your explanation of a SI unit of time, I think I would be
correct in saying all the standard time pieces presently used
throughout the world would become obsolete. Past accepted time
recording practices then becoming obsolete would have a domino effect
upon written history of mankind.

If, or when (whichever the case) a change of common time is proposed
and might well be accepted by the ISO, would you still find engineering
data incomprehensible if time related data was not, or did not, make
reference to metric time changes? Would you expect world (or the US,
for that matter) use of common standard time to be trashed in favor of
using metric time, just because the ISO accepted the definition of what
common standard time should be? Wouldn't history have to be rewritten
just to satisfy metrication. Years from now would you really care one
way or another? :-)

This is all highly specious; the SI unit of time is the second, and any
other usage is derived from this to suit the need. The chance of any
change like the ones you postulate are, dare I say, minute.

David
--
David Littlewood