"telephoto" - another definition problem

BC writes: I suspect that the original definition is the one
involving the
telephoto ratio that optics people have always used, and the other
definition grew up around a popular misunderstanding of the term.

I agree. In the 'old days' a thin pocketable rigid camera was not in
vogue as it is with today's very thin digital. Foldable cameras were
the compact camera of yesteryear, and rollfilm or 35mm canister
thickness forced cameras to all have a certain minimum for the body
depth. And cameras with telescoping lens assemblies that nested into
the body for storage were possible even without telephoto design being
needed. And telephoto design lenses were not very terrific optically
until the science of lens design was greatly improved. So telephoto
design lenses (vs. long focus lenses) were used primarily for long
focal length only to keep lens length (and weight) down, but the design
was not needed for 'normal' focal length to keep the
front-element-fo-film distance small in order to permit a thin camera
body.

--Wilt

BC wrote:
I suspect that the original definition is the one involving the
telephoto ratio that optics people have always used, and the other
definition grew up around a popular misunderstanding of the term. I
recognize that usage rules, but reserve the right to complain about it!

The technical meaning made a lot of sense to large format
camera users. If you want a 15 inch (380mm) lens on your
4x5 Graflex, you definitely want a telephoto lens, because
you don't have enough bellows extension to cope with a
regular lens that long.

It made a lot less sense to the users of miniature cameras.
The 135 mm lenses for the Leica (Elmar and Hektor) were a
little longer than 135mm from the film plane to the front
surface of the lens, but they filled much the same function
as the 15 inch lens on the Graflex. The 135mm Sonnar lens
for the Contax was only around 129mm from film plane to
the front of the lens when focussed at infinity and thus
was a telephoto by your definition. I don't think that
making the lens slightly shorter was an important factor
in the design: it was just how Bertele's design worked out.

It seems a little odd to call the 35mm lens on the Olympus
Stylus Epic a telephoto lens, and to deny that status to
a 300mm Nikkor. People who study photographic optics,
large-format camera users, and language pedants will all
know what is meant, but the much larger group who know
only the popular meaning will not be able to make any sense of it.

Technical vocabulary often acquires popular meanings
which are only slightly connected to their technical
meanings. Even good dictionaries sometimes list the
popular meaning and miss the technical one. For instance,
"milled coinage" has a technical meaning of "coins struck
with a machine, originally a screw press, later a steam driven
or electrical press" and has nothing to do with reeded
edges except that milled coins often have such edges.
But in popular language, and even in some dictionaries,
it does refer to the edges and one can be accused of being
pedantic if one insists on the technical meaning.

Peter.
--

"BC" wrote in message
oups.com...
I suspect that the original definition is the one involving the
telephoto ratio that optics people have always used, and the other
definition grew up around a popular misunderstanding of the term.

The later should be 'telescopic', as in collapsible. No? My two-bits worth.

jjs wrote:
"BC" wrote in message
oups.com...
I suspect that the original definition is the one involving the
telephoto ratio that optics people have always used, and the other
definition grew up around a popular misunderstanding of the term.

The later should be 'telescopic', as in collapsible. No? My two-bits
worth.

Then should a "telescope" be collapsible or only if it is a "telescopic
telescope"?

wilt wrote:
BC writes: I suspect that the original definition is the one
involving the
telephoto ratio that optics people have always used, and the other
definition grew up around a popular misunderstanding of the term.

I agree. In the 'old days' a thin pocketable rigid camera was not in
vogue as it is with today's very thin digital. Foldable cameras were
the compact camera of yesteryear, and rollfilm or 35mm canister
thickness forced cameras to all have a certain minimum for the body
depth. And cameras with telescoping lens assemblies that nested into
the body for storage were possible even without telephoto design
being
needed. And telephoto design lenses were not very terrific optically
until the science of lens design was greatly improved. So telephoto
design lenses (vs. long focus lenses) were used primarily for long
focal length only to keep lens length (and weight) down, but the
design
was not needed for 'normal' focal length to keep the
front-element-fo-film distance small in order to permit a thin camera
body.

--Wilt

The first wide-angle telephoto lenses were introduced by Olympus back
in the mid-1970's when they began marketing extremely compact 35mm film
cameras. The first patent reference that I'm aware of is U.S.
3,951,523 (assigned to Olympus), which features lens designs covering
62 degrees field of view (suitable for a 35mm focal length on 35mm film
format) with a telephoto ratio less than 0.9. This lens type became
extremely popular during the late 1970's through the 1980's, but began
to decline during the 1990's when compact zoom lenses started to become
much more common.

The use of a true telephoto construction proved beneficial even for a
slightly wide angle lens because camera thickness is a critical
parameter. If a camera is too fat, then you can't put it in a shirt
pocket. Even though you are correct that the film canister represents
an irreducible minimum for the camera thickness, you still need a very
compact lens system to ensure that the actual thickness doesn't get too
much larger than the absolute minimum value.

You're also correct that telescoping lenses help reduce thickness.
However, this construction was used almost entirely with zoom lenses,
so fixed focal length compact 35mm cameras have always required a
compact lens design.

True telephoto lenses are almost never used on compact digicams. These
cameras achieve compactness mainly by the use of a small image format,
and to a lesser extent by clever packaging (e.g. folded optical path).

Brian
www.caldwellphotographic.com

jjs wrote:

"BC" wrote in message
oups.com...
I suspect that the original definition is the one involving the
telephoto ratio that optics people have always used, and the other
definition grew up around a popular misunderstanding of the term.

The later should be 'telescopic', as in collapsible. No? My two-bits
worth.

'Telescope' means far-watching. Funny how it has become associated with
things like a collapsible fishing rod...
http://www.bartleby.com/61/roots/IE488.html

-- Lassi

"Lassi Hippeläinen" wrote in message
...

'Telescope' means far-watching. Funny how it has become associated with
things like a collapsible fishing rod...
http://www.bartleby.com/61/roots/IE488.html

Metathesized this! (extended grin)