DSLR vs P&S a replay of Film vs Digital?

William Graham wrote:

One could design a motorized zoom that was simply an amplified stepper motor
that was driven by a hand-operated positioning of a smaller lens-like
device.....IOW, you would turn a cylinder just like a lens zoom, but the
motor would then position the (presumably) larger lens zoom via a
differential sensing stepper motor, so it would have the "feel" of a
hand-operated zoom lens. But it still wouldn't be as good as zooming a
smaller lens by hand. It would just be a close approximation to having the
same feel, and would work well if you didn't go faster than the powered
driver was capable of following.

I guess that would be possible, but other than being able to remotely
control the zoom, what would be the advantage? Canon once had a
motorized zoom lens, the EF 35-80mm f/4-5.6 PZ, but it could only be
zoomed with the buttons.

The motorized zooms are on P&S cameras because they're cheap, and the
motor is already there. It's a much less capable system than the manual
zoom ring, but it's cheaper and smaller.

It's not like power windows on cars, where the motorized system is not
only cheaper, but also more capable (if much more expensive to fix).
Those little motors are dirt cheap, but replacements cost a fortune.

On Mon, 19 Nov 2007 16:54:35 -0800, SMS ???• ?
wrote in
:

William Graham wrote:

One could design a motorized zoom that was simply an amplified stepper motor
that was driven by a hand-operated positioning of a smaller lens-like
device.....IOW, you would turn a cylinder just like a lens zoom, but the
motor would then position the (presumably) larger lens zoom via a
differential sensing stepper motor, so it would have the "feel" of a
hand-operated zoom lens. But it still wouldn't be as good as zooming a
smaller lens by hand. It would just be a close approximation to having the
same feel, and would work well if you didn't go faster than the powered
driver was capable of following.

I guess that would be possible, but other than being able to remotely
control the zoom, what would be the advantage?

None, because it's way too primitive, on the order of a 1976 floppy
disc. Much better servo systems are readily available.

anon once had a
motorized zoom lens, the EF 35-80mm f/4-5.6 PZ, but it could only be
zoomed with the buttons.

And you have zero experience with it, so you have no idea how well it
worked.

The motorized zooms are on P&S cameras because they're cheap, and the
motor is already there.

Actually because it allows great freedom in lens design that's not
possible on interchangeable parfocal zoom.

It's a much less capable system than the manual
zoom ring, but it's cheaper and smaller.

Actually quite effective, at least to those of us that have learned how
to use them effectively.

It's not like power windows on cars, where the motorized system is not
only cheaper, but also more capable (if much more expensive to fix).
...

Hung by your own analogy. A power zoom system can likewise be more
capable than a manual zoom system.

--
Best regards,
John Navas
Panasonic DMC-FZ8 (and several others)

In article , John Navas
wrote:

Mechanical zoom is only single speed, has no acceleration, and is
limited by mass, friction, and hand-eye coordination.

nonsense. mechanical zoom has whatever speed and acceleration the user
wants, subject to the same mechanical limitations that apply with a
power zoom (mass and friction) as well as hand-eye coordination. or
are you saying that a powered zoom magically dispenses with all that?

furthermore, powered zoom is dependent on a predetermined motor speed
and it can't be any faster than the motor itself can turn. of course,
it *could* have a superfast and superpowerful motor in it, but
unfortunately, that's not the case, at least not at a marketable price
point.

They're actually pretty good, especially considering their relatively
primitive design, and will undoubtedly continue to get better.

not having the ability to travel into the future, i'm only interested
in what exists now. ymmv.

In article
,
acl wrote:

actually pentax had a few slr lenses with power zoom and they didn't
sell that well.

minolta had some too (the xi series), but discontinued them and
switched back to manual zoom.
Clearly they missed the wave of the future there.

canon had one too. obviously, they weren't better than mechanical zoom.

On Mon, 19 Nov 2007 17:34:04 -0800, nospam wrote
in :

In article , John Navas
wrote:

Mechanical zoom is only single speed, has no acceleration, and is
limited by mass, friction, and hand-eye coordination.

nonsense. mechanical zoom has whatever speed and acceleration the user
wants, subject to the same mechanical limitations that apply with a
power zoom (mass and friction) as well as hand-eye coordination. or
are you saying that a powered zoom magically dispenses with all that?

Read what I wrote more carefully.

furthermore, powered zoom is dependent on a predetermined motor speed
and it can't be any faster than the motor itself can turn. of course,
it *could* have a superfast and superpowerful motor in it, but
unfortunately, that's not the case, at least not at a marketable price
point.

That's not true either.

They're actually pretty good, especially considering their relatively
primitive design, and will undoubtedly continue to get better.

not having the ability to travel into the future, i'm only interested
in what exists now. ymmv.

What exists now works just fine, if you learn how to use it effectively.
YMMV indeed.

--
Best regards,
John Navas
Panasonic DMC-FZ8 (and several others)

On Mon, 19 Nov 2007 17:34:05 -0800, nospam wrote
in :

In article
,
acl wrote:

actually pentax had a few slr lenses with power zoom and they didn't
sell that well.

minolta had some too (the xi series), but discontinued them and
switched back to manual zoom.
Clearly they missed the wave of the future there.

canon had one too. obviously, they weren't better than mechanical zoom.

Apples and oranges -- those were relatively massive interchangeable
parfocal zooms, not relatively small fixed varifocal lenses.

--
Best regards,
John Navas
Panasonic DMC-FZ8 (and several others)

"nospam" wrote in message
...
In article , William
Graham wrote:

muscle memory also plays a role. i know exactly how far to turn the
zoom ring to get to where i need, whereas there's a latency with a
fly-by-wire ring, and with two buttons, it is simply impossible.

Yes. - My gut instinct tells me that auto zoom mechanisms are only useful
where the machine is too big for you to conveniently get your hands
around
it to turn it manually, so you have to have it driven automatically.

you mean like this?

http://www.sigma-photo.co.jp/english/news/200_500_28.htm

it has built in zoom and focus motors including its own power supply
for them. not that it is actually shipping or anything -- sigma
produces more vaporware than anyone else.

Otherwise, there is nothing to be gained by driving it
automatically.....It
won't be better than manual operation. Obviously, Mt. Palomar has to be
zoomed automatically, but my Nikkors will operate most efficiently if I
zoom
them by hand.

actually pentax had a few slr lenses with power zoom and they didn't
sell that well.

http://www.mosphotos.com/PentaxLensPowerZoom.html

The ability to memorize and recall a given focal length might be useful for
some rather rare applications.....And certainly, the ability to slew the
zoom from a remote location is useful too. So, I have nothing against the
development and manufacture of power zoom mechanisms. It's just that they
are a poor choice if one can actually be there and do the zooming by hand.
But then, that could be said for lots of things........

In article , John Navas
wrote:

actually pentax had a few slr lenses with power zoom and they didn't
sell that well.

minolta had some too (the xi series), but discontinued them and
switched back to manual zoom.
Clearly they missed the wave of the future there.

canon had one too. obviously, they weren't better than mechanical zoom.

Apples and oranges -- those were relatively massive interchangeable
parfocal zooms, not relatively small fixed varifocal lenses.

it's not apples and oranges at all.

the correct comparison is with two identical lenses (or as close to
identical as possible), one with a zoom motor and one without. any
other comparison introduces many different variables, only one of which
is the zoom motor.

"John Navas" wrote in message
...
On Mon, 19 Nov 2007 12:14:27 -0500, "Neil Harrington"
wrote in
:

"Chester D" wrote in message
. ..

but often I find that
the electronic zoom on my other P&S cameras as just as good for this.

If by "electronic zoom" you mean zoom by push button, there's no way
that's
anywhere near as fast or accurate as a real manual zoom. I love my Nikon
Coolpixes, and can live with the rocker switch zoom but it's a poor
substitute for manual. I can understand why they had to do it that way for
the sake of compactness (even on my 8700 and 8800 which are not so
compact),
but that doesn't make me like it any better.

A sample of two does not a truth make,

I must have over 25 digital cameras, at least 15 being compacts of several
different makes with motorized zoom. You may say "a sample of 15 does not a
truth make" either, but I submit it's enough to give the user a fair idea of
how motorized zoom compares with manual zoom.


and motorized zoom on the Canon
Pro1 is better than on your Nikons.

I don't have that model but I do have three other Canons with motorized
zoom. There isn't that much difference between any of them, really. You
might say one make/model is a little better than another, but none compare
with any real manual zoom. My preference is actually for the Nikon 8xxx
series because I prefer the rocker button placement and they're perhaps a
bit smoother than most, but still not comparable to any manual zoom. It's
really silly to argue this point, John.


Fly by wire can be much better than
manual control, as any qualified commercial or military pilot would tell
you.

For military or commercial aircraft, yes. There are reasons for that that
have absolutely no connection with the operation of zoom lenses.


So much depends on how quickly and how well the
photographer can learn to use new tools to their best advantages.
Clearly
some
of them are still stuck in the last-century and can't get past that bump
in
their learning curve that will take them into this century.

guffaw!

There is no "bump in the learning curve" that when you "get past" suddenly
converts an inferior system into an equally good one.

The "bump in the learning curve" is when a photographer learns how to
use a tool effectively. What matters is the photographer, not the tool.

*Both* matter. It's not an either-or question. Some tools are better than
others.


Power zoom, however
accomplished, is simply more awkward, slower and miuch less precise than
manual zoom. Anyone who's used both knows this.

There's nothing inherently "inferior" about motorized zoom, which can
actually be more precise in terms of focus than manual zoom

No way, John. Imagine trying to turn an adjustment screw with a motorized
screwdriver. I'm all for automation where it's of benefit, but there are
some things it's just better to do manually.


-- it's just
different, as any good photographer knows.

Different and inferior, from the standpoint of speed and accuracy.

Neil

"John Navas" wrote in message
...
On Mon, 19 Nov 2007 15:08:26 -0800, "William Graham"
wrote in :

"nospam" wrote in message
. ..

muscle memory also plays a role. i know exactly how far to turn the
zoom ring to get to where i need, whereas there's a latency with a
fly-by-wire ring, and with two buttons, it is simply impossible.

Yes. - My gut instinct tells me that auto zoom mechanisms are only useful
where the machine is too big for you to conveniently get your hands around
it to turn it manually, so you have to have it driven automatically.
Otherwise, there is nothing to be gained by driving it
automatically.....It
won't be better than manual operation. Obviously, Mt. Palomar has to be
zoomed automatically, but my Nikkors will operate most efficiently if I
zoom
them by hand.

Your gut is not correct -- see my prior response on fast servo control.

Well, not to worry. Auto zooming certainly has its place in remote
controlled TV systems and the like. (Moon landers, for example, and cameras
mounted on the tops of towers and the like) Just because I don't need them
for the lenses on my F5, that shouldn't slow any enterprising developers
down.....I am simply stating the obvious: That the fewer items that you have
to put in between the operator and the machine the faster and better will be
the operation. That being said, the ability to remember and return to a
previous setting could be very useful, and most auto controlled machinery is
capable of this.