[OT] eBay: Another Unbelievable Item Description

"Bob Hickey" wrote in message
...

"Chris Brown" wrote in message
...
In article ,
Jim Phelps wrote:

That's technically correct. If a square millimetre of film absorbs light
at
the rate of N photons per second with an f/4 lens, then an f/2 lens will
allow the same piece of film to absorb 4N photons per second.
That's like saying that if a Lincoln and VW travel from point A to B at
exactly the same speed, the Lincoln is much faster. It's not; there's
just
twice as much of it. Bob Hickey



Actually, if the transfer of "it" is the issue, then the VW would have to
make two trips to accomplish the same function, and presumably take twice
the time, assuming you are correct and there is "twice as much of "it" in
the Lincoln," whatever, "it" is.

Eric Miller

In article ,
Bob Hickey wrote:

"Chris Brown" wrote in message
...
In article ,
Jim Phelps wrote:

That's technically correct. If a square millimetre of film absorbs light
at
the rate of N photons per second with an f/4 lens, then an f/2 lens will
allow the same piece of film to absorb 4N photons per second.

That's like saying that if a Lincoln and VW travel from point A to B at
exactly the same speed, the Lincoln is much faster. It's not; there's just
twice as much of it. Bob Hickey

No it's not, it's like saying that a car with 4 people in delivers people to
their destination at a faster rate than a car with 2 people in, and it's
perfectly accurate.

Perhaps the eBay seller has made some mistakes, but this isn't one of them.

In article ,
Bob Hickey wrote:

"Chris Brown" wrote in message
...
In article ,
Jim Phelps wrote:

That's technically correct. If a square millimetre of film absorbs light
at
the rate of N photons per second with an f/4 lens, then an f/2 lens will
allow the same piece of film to absorb 4N photons per second.

That's like saying that if a Lincoln and VW travel from point A to B at
exactly the same speed, the Lincoln is much faster. It's not; there's just
twice as much of it. Bob Hickey

No it's not, it's like saying that a car with 4 people in delivers people to
their destination at a faster rate than a car with 2 people in, and it's
perfectly accurate.

Perhaps the eBay seller has made some mistakes, but this isn't one of them.

Bob Hickey wrote:
"Chris Brown" wrote in message
...

In article ,
Jim Phelps wrote:


That's technically correct. If a square millimetre of film absorbs light

at

the rate of N photons per second with an f/4 lens, then an f/2 lens will
allow the same piece of film to absorb 4N photons per second.

That's like saying that if a Lincoln and VW travel from point A to B at
exactly the same speed, the Lincoln is much faster. It's not; there's just
twice as much of it. Bob Hickey

Better put would be: a bus travelling from A to B fills the destination with
passengers faster than a VW travelling from A to B at the same speed.

It's about rate of delivery, not the velocity of the photons.

Wideband data networks don't move a given bit quicker than a narrow band one,
just more bits per unit time.

Want to keep playing?

Cheers,
Alan.

--
-- r.p.e.35mm user resource: http://www.aliasimages.com/rpe35mmur.htm
-- r.p.d.slr-systems: http://www.aliasimages.com/rpdslrsysur.htm
-- [SI] gallery & rulz: http://www.pbase.com/shootin
-- e-meil: there's no such thing as a FreeLunch.

Bob Hickey wrote:
"Chris Brown" wrote in message
...

In article ,
Jim Phelps wrote:


That's technically correct. If a square millimetre of film absorbs light

at

the rate of N photons per second with an f/4 lens, then an f/2 lens will
allow the same piece of film to absorb 4N photons per second.

That's like saying that if a Lincoln and VW travel from point A to B at
exactly the same speed, the Lincoln is much faster. It's not; there's just
twice as much of it. Bob Hickey

Better put would be: a bus travelling from A to B fills the destination with
passengers faster than a VW travelling from A to B at the same speed.

It's about rate of delivery, not the velocity of the photons.

Wideband data networks don't move a given bit quicker than a narrow band one,
just more bits per unit time.

Want to keep playing?

Cheers,
Alan.

--
-- r.p.e.35mm user resource: http://www.aliasimages.com/rpe35mmur.htm
-- r.p.d.slr-systems: http://www.aliasimages.com/rpdslrsysur.htm
-- [SI] gallery & rulz: http://www.pbase.com/shootin
-- e-meil: there's no such thing as a FreeLunch.

On Fri, 14 Jan 2005 00:29:16 GMT, Chris Brown
wrote:

In article ,
Bob Hickey wrote:

"Chris Brown" wrote in message
...
In article ,
Jim Phelps wrote:

That's technically correct. If a square millimetre of film absorbs light
at
the rate of N photons per second with an f/4 lens, then an f/2 lens will
allow the same piece of film to absorb 4N photons per second.

That's like saying that if a Lincoln and VW travel from point A to B at
exactly the same speed, the Lincoln is much faster. It's not; there's just
twice as much of it. Bob Hickey

No it's not, it's like saying that a car with 4 people in delivers people to
their destination at a faster rate than a car with 2 people in, and it's
perfectly accurate.


Semantics.

The bigger lens allows faster shutter speeds. So it is "faster".
Whether it is technically correct is really irrelevant. The term
stuck. I think it is a good descriptive term.

J.

On Fri, 14 Jan 2005 00:29:16 GMT, Chris Brown
wrote:

In article ,
Bob Hickey wrote:

"Chris Brown" wrote in message
...
In article ,
Jim Phelps wrote:

That's technically correct. If a square millimetre of film absorbs light
at
the rate of N photons per second with an f/4 lens, then an f/2 lens will
allow the same piece of film to absorb 4N photons per second.

That's like saying that if a Lincoln and VW travel from point A to B at
exactly the same speed, the Lincoln is much faster. It's not; there's just
twice as much of it. Bob Hickey

No it's not, it's like saying that a car with 4 people in delivers people to
their destination at a faster rate than a car with 2 people in, and it's
perfectly accurate.


Semantics.

The bigger lens allows faster shutter speeds. So it is "faster".
Whether it is technically correct is really irrelevant. The term
stuck. I think it is a good descriptive term.

J.

Gentlemen, Please!

You have missed the point! The post is talking about the LENS, not the
FILM [sensor]! He states the bigger the front element the faster the rate
of absorbtion! Lenses DON'T ABSORB LIGHT in sufficent quantities (refract,
reflect, distort - yes, but not absorb; exception: Holga)! A [more]
correct statement would be a bigger front element allows more light to be
transferred to the film or sensor.

All your examples are destination oriented. This is not about the
destination, but rather the transfer mechanism (in this case a lens). The
phone line, data circuit, nor the highway changes the speed or rate of
delivery (as you have all pointed out). It does not matter how fast the
people/bits/photons accumulate at the destination. It's about how fast you
can travel on the highway/data line/laws of physics, and they all have speed
limits! That was the point. The lens does not enable/disable the photons
from transferring through the lens at a faster rate. They all travel at a
given rate - the speed of light.

To use the highway example, a fast lens would be a 12 lane highway, a
slow lens a 4 lane highway. The speed limit is 65MPH and everyone travels
at this speed. I agree the 12 lane highway would allow more people to reach
their destination, but not quicker per person. I disagree the people moved
faster on the highway. They all transited the highway at the same rate of
speed. The film is the destination and the lens is the highway. The
description was about the lens and therefore inaccurate.

Another missed point:

I don't know about many of you, but I personally don't think a 28mm/3.5
lens is fast! Same for an 80/4.5! My 50mm/3.5 Macro is faster than this
zoom would be in the 50mm position and it's the slowest lens I own (in
35mm)! Maybe this is what the seller was referring to as absorbtion in the
lens;~).

Gentlemen, Please!

You have missed the point! The post is talking about the LENS, not the
FILM [sensor]! He states the bigger the front element the faster the rate
of absorbtion! Lenses DON'T ABSORB LIGHT in sufficent quantities (refract,
reflect, distort - yes, but not absorb; exception: Holga)! A [more]
correct statement would be a bigger front element allows more light to be
transferred to the film or sensor.

All your examples are destination oriented. This is not about the
destination, but rather the transfer mechanism (in this case a lens). The
phone line, data circuit, nor the highway changes the speed or rate of
delivery (as you have all pointed out). It does not matter how fast the
people/bits/photons accumulate at the destination. It's about how fast you
can travel on the highway/data line/laws of physics, and they all have speed
limits! That was the point. The lens does not enable/disable the photons
from transferring through the lens at a faster rate. They all travel at a
given rate - the speed of light.

To use the highway example, a fast lens would be a 12 lane highway, a
slow lens a 4 lane highway. The speed limit is 65MPH and everyone travels
at this speed. I agree the 12 lane highway would allow more people to reach
their destination, but not quicker per person. I disagree the people moved
faster on the highway. They all transited the highway at the same rate of
speed. The film is the destination and the lens is the highway. The
description was about the lens and therefore inaccurate.

Another missed point:

I don't know about many of you, but I personally don't think a 28mm/3.5
lens is fast! Same for an 80/4.5! My 50mm/3.5 Macro is faster than this
zoom would be in the 50mm position and it's the slowest lens I own (in
35mm)! Maybe this is what the seller was referring to as absorbtion in the
lens;~).

In article ,
Jim Phelps wrote:
Gentlemen, Please!

You have missed the point! The post is talking about the LENS, not the
FILM [sensor]! He states the bigger the front element the faster the rate
of absorbtion! Lenses DON'T ABSORB LIGHT in sufficent quantities

Indeed they don't, but something does, namely the film. One of the great
things about English, and other natural languages, is that you're allowed to
leave certain things implicit, because they're obvious by context. This
does, of course, present an opportunity for those with nothing better to do
to pretend they're some sort of Mr Spock-like space alien, ignore the
implicit context, and pretend some sort of ambiguity exists where in reality
there is none. Presumably this is done because people think this has some
sort of humour value, but in this case, the joke appears to have fallen flat.

Larger apertures allow a faster rate of light absorption. This being stated
by someone in a slightly clumsy manner would not seem to be a great source
of comedic value, but if it floats your boat...

All your examples are destination oriented. This is not about the
destination, but rather the transfer mechanism (in this case a lens).

I tend to put my lenses in front of some sort of light sensing material,
e.g. photopgraphic film, but then I read this group because I have a
photography hobby, not because I have a newsgroup pedantry hobby. YMMV.