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-   -   Are primes brighter and sharper than wide open zooms (http://www.photobanter.com/showthread.php?t=49519)

Siddhartha Jain September 28th 05 03:33 PM

Are primes brighter and sharper than wide open zooms
 
Hi,

Given two lenses, one a prime (say 28mm) and the other a zoom (say
28-75mm) and both with an aperture of f2.8 -
- Will the prime be brighter than the zoom because it has fewer lens
elements?
- Will the prime be sharper wide open than the zoom at 28mm?

Ofcourse, a lot will depend on the particular makes and models being
compared but is there a rule of thumb?

- Siddhartha


Joseph Meehan September 28th 05 04:01 PM

Siddhartha Jain wrote:
Hi,

Given two lenses, one a prime (say 28mm) and the other a zoom (say
28-75mm) and both with an aperture of f2.8 -
- Will the prime be brighter than the zoom because it has fewer lens
elements?
- Will the prime be sharper wide open than the zoom at 28mm?

Ofcourse, a lot will depend on the particular makes and models being
compared but is there a rule of thumb?

- Siddhartha


In a word NO. At least it is no if you are talking about real life
situations.

However ---- In general primes will be sharper unless the zoom is a
much better quality lens. Of course that is possible and a really good zoom
can outperform a poor prime any day.

--
Joseph Meehan

Dia duit



Digital Photography Now September 28th 05 04:15 PM

A good prime should be sharper and exhibit fewer optical aberrations
compared to a zoom, with the aperture set wide open. Stopping the zoom down
should improve sharpness, but then you may lose the desirable effect of
limited depth of field, if that's what you wanted. Zooms typically have
different geometric distortion throughout the zoom range, usually barrell at
the wide end and pincushion at the tele end, being neutral somewhere in the
middle. A good prime should be able to combine better sharpness, contrast
and distortion characteristics compared to a zoom.

But there are some outstanding zooms out there these days and the advantage
of primes has been lessened as a result.

As the apertures are the same, there should be no difference in brightness.
The glass doesn't lose enough light in the way you fear to be a major
factor.

Ian

Digital Photography Now
http://dpnow.com
Visit our discussion forum at http://dpnow.com/Forums.html


"Siddhartha Jain" wrote in message
ups.com...
Hi,

Given two lenses, one a prime (say 28mm) and the other a zoom (say
28-75mm) and both with an aperture of f2.8 -
- Will the prime be brighter than the zoom because it has fewer lens
elements?
- Will the prime be sharper wide open than the zoom at 28mm?

Ofcourse, a lot will depend on the particular makes and models being
compared but is there a rule of thumb?

- Siddhartha




[email protected] September 28th 05 04:15 PM

The prime may be slightly brighter than the zoom, something which may
be more important in the motion-picture industry
They use a term called the "t stop" of a lens and it is a measure of
the light loss through a lens.
http://artsci-ccwin.concordia.ca/comm/lighting.htm
The difference could be as little as a third or as great as (or greater
than) a 2 stop difference between what the f-stop is and the t-stop,
while the DoF will be the same and sharpnes is likely to be less with a
zoom than a prime.
In real life still photography I don't believe it would be noticable
(the difference in brightness), because of a variety of factors.
I personally would not lose any sleep over it.


David Littlewood September 28th 05 04:42 PM

In article . com,
Siddhartha Jain writes
Hi,

Given two lenses, one a prime (say 28mm) and the other a zoom (say
28-75mm) and both with an aperture of f2.8 -
- Will the prime be brighter than the zoom because it has fewer lens
elements?
- Will the prime be sharper wide open than the zoom at 28mm?

Ofcourse, a lot will depend on the particular makes and models being
compared but is there a rule of thumb?

- Siddhartha

Other things being equal, yes to both, though with well-designed modern
lenses the difference may be small.

Brightness:

The conventional f-stop designation of aperture is a purely geometric
measure and takes no account of the actual transmission properties of
the lens. In reality, not all of the light going into a lens will come
out at the other end, and some of the light that does come out will be
scattered, and hence will reduce image quality.

Attenuation takes two forms: absorption and reflection/scattering.
Absorption is purely proportional to the depth of glass; a typical
figure for normal optical glass would be 10% for a total glass path
length of 100mm. Most photographic lenses would fall far short of this,
though some big lenses may get there. This attenuation is entirely
proportional to the length of the light path through glass; thus a zoom
with 12-15 elements is likely to experience more absorption than a fixed
focal length lens with 5-10 elements.

The other form is reflection from glass-air interfaces. This is
unavoidable, but can be reduced very greatly by coating. The percentage
of reflection depends on the refractive index of the glass, but for
typical n=1.50 optical glass (uncoated) the percentage is about 4%.
This, remember, is at each glass air interface, two per lens element.
Thus a compound lens with 15 elements will have 30 interfaces, and will
only transmit (0.96)^30 or about 20% of the light. (In fact another
20-40% will get to the film or sensor as scattered light - giving an
image of appallingly bad contrast). A single layer coating will reduce
the reflection to about 1-1.5%, and modern multi-coating reduces it to
around 0.3-0.5%.

This still gives a transmission factor of about 83.5% for a 20-surface
(10-element) system, against 91.4% for a 10-surface (5-element) system.

Resolution:

There is not the same direct relationship between complexity and
resolution as that above between complexity and transmission. However,
the compromises required to balance zoom ratio, overall size, mechanical
complexity and cost at the same time as controlling the seven distinct
varieties of lens aberrations mean that in almost every case the zoom
lens will have lower resolution than the fixed focal length lens of
similar quality of design and manufacture. You can see this from the MTF
function curves published by most lens manufacturers. Having just
checked some of these myself to answer your question, I am actually
quite impressed by how small these differences are; a couple of decades
ago the differences would have been much greater. (Be aware when
comparing MTF curves that they usually show wide open and f/8 data; as a
zoom will usually have a smaller maximum aperture than the comparable
fixed focal length lenses, you should avoid comparing these - best look
at the f/8 curves for a fair comparison.)

David
--
David Littlewood

Nostrobino September 28th 05 04:57 PM

Zoom lenses ARE prime lenses, notwithstanding the now-popular misusage of
"prime."

A prime lens is the camera lens as distinct from some other lens or
lenticular device (close-up lens, tele converter, etc.) used with it. It has
meant that since long before zoom lenses became commonplace, and therefore
no need to use another term to mean "non-zoom."

"Prime" is properly used in the sense of primary, main, chief or
original--all dictionary definitions for "prime."

There is NO dictionary definition for "prime" which means fixed focal length
or single focal length, or fixed or single anything else.

It would be nice if this nonsensical misusage, which obviously is based on
someone's misunderstanding of the term some years ago (and then spread like
cancer through the power of the Internet) could be stamped out. Surely "FFL"
is at least as easy to type as "prime" anyway, and there never was any
reason other than shortness to replace "fixed focal length" with the
incorrect term.

N.



Siddhartha Jain September 28th 05 05:25 PM

Nostrobino wrote:
Zoom lenses ARE prime lenses, notwithstanding the now-popular misusage of
"prime."

A prime lens is the camera lens as distinct from some other lens or
lenticular device (close-up lens, tele converter, etc.) used with it. It has
meant that since long before zoom lenses became commonplace, and therefore
no need to use another term to mean "non-zoom."

"Prime" is properly used in the sense of primary, main, chief or
original--all dictionary definitions for "prime."

There is NO dictionary definition for "prime" which means fixed focal length
or single focal length, or fixed or single anything else.

It would be nice if this nonsensical misusage, which obviously is based on
someone's misunderstanding of the term some years ago (and then spread like
cancer through the power of the Internet) could be stamped out. Surely "FFL"
is at least as easy to type as "prime" anyway, and there never was any
reason other than shortness to replace "fixed focal length" with the
incorrect term.


I am aware of the mis-usage of the term *prime* and so guilty of
propogating the mis-usage but I feel its time the FFL camp realised
that there is no turning back.

- Siddhartha


Nostrobino September 28th 05 06:35 PM


"Siddhartha Jain" wrote in message
ups.com...
Nostrobino wrote:
Zoom lenses ARE prime lenses, notwithstanding the now-popular misusage of
"prime."

A prime lens is the camera lens as distinct from some other lens or
lenticular device (close-up lens, tele converter, etc.) used with it. It
has
meant that since long before zoom lenses became commonplace, and
therefore
no need to use another term to mean "non-zoom."

"Prime" is properly used in the sense of primary, main, chief or
original--all dictionary definitions for "prime."

There is NO dictionary definition for "prime" which means fixed focal
length
or single focal length, or fixed or single anything else.

It would be nice if this nonsensical misusage, which obviously is based
on
someone's misunderstanding of the term some years ago (and then spread
like
cancer through the power of the Internet) could be stamped out. Surely
"FFL"
is at least as easy to type as "prime" anyway, and there never was any
reason other than shortness to replace "fixed focal length" with the
incorrect term.


I am aware of the mis-usage of the term *prime* and so guilty of
propogating the mis-usage but I feel its time the FFL camp realised
that there is no turning back.


Well, not necessarily, though of course the more people who misuse the term,
the harder it will be to correct it.

Most people do not want to use wrong terminology since it makes them look
ignorant. In the case of "prime" being used to mean FFL, this has only
spread because readers who have not seen the term before, and then see it
used by people they assume are knowledgeable, naturally adopt it themselves.
Thus newbies are caught up in the misusage and (perhaps partly because they
feel using jargon will make them look knowledgeable too), contribute to the
spread.

Some will continue to use it anyway, but others will drop it (and some have
dropped it) when the error is pointed out to them.

N.



Eric Miller September 28th 05 07:07 PM


"Nostrobino" wrote in message
...
Zoom lenses ARE prime lenses, notwithstanding the now-popular misusage of
"prime."

A prime lens is the camera lens as distinct from some other lens or
lenticular device (close-up lens, tele converter, etc.) used with it. It
has meant that since long before zoom lenses became commonplace, and
therefore no need to use another term to mean "non-zoom."

"Prime" is properly used in the sense of primary, main, chief or
original--all dictionary definitions for "prime."

There is NO dictionary definition for "prime" which means fixed focal
length or single focal length, or fixed or single anything else.

It would be nice if this nonsensical misusage, which obviously is based on
someone's misunderstanding of the term some years ago (and then spread
like cancer through the power of the Internet) could be stamped out.
Surely "FFL" is at least as easy to type as "prime" anyway, and there
never was any reason other than shortness to replace "fixed focal length"
with the incorrect term.

N.


Many now accepted meanings of words have been created through misusage.
Perhaps you would prefer a dead language to English?

Eric Miller



Mark Roberts September 28th 05 07:07 PM

"Siddhartha Jain" wrote:

Given two lenses, one a prime (say 28mm) and the other a zoom (say
28-75mm) and both with an aperture of f2.8 -
- Will the prime be brighter than the zoom because it has fewer lens
elements?
- Will the prime be sharper wide open than the zoom at 28mm?

Ofcourse, a lot will depend on the particular makes and models being
compared but is there a rule of thumb?


The rule of thumb is that it depends on the make and model.


--
Mark Roberts
Photography and writing
www.robertstech.com

Jeremy September 28th 05 07:57 PM


"Siddhartha Jain" wrote in message
ups.com...
Hi,

Given two lenses, one a prime (say 28mm) and the other a zoom (say
28-75mm) and both with an aperture of f2.8 -
- Will the prime be brighter than the zoom because it has fewer lens
elements?
- Will the prime be sharper wide open than the zoom at 28mm?

Ofcourse, a lot will depend on the particular makes and models being
compared but is there a rule of thumb?

- Siddhartha


In theory, zooms will always be somewhat below the quality of prime lenses.
Zooms typically have barrel distortion at one end of the zoom range, and
pincushion distortion at the other. Older zooms, especially those that did
not have decent multicoating, were more prone to flare and ghosting, because
of the light bouncing back and forth off the air-to-glass surfaces.

The margin of superiority of primes over zooms has narrowed, and many
photographers find the convenience and economy of one zoom versus several
primes to be more important than some slight degree of image degradation. I
have a couple of Pentax zooms in K-mount that do a credible job, and it
certainly is easier to carry two zooms than it is to carry 5 or 6 primes.
Thirty years ago, I bought a couple of third-party zooms for my M43 bodies,
and the results were just awful, relative to my SMC Takumar prime lens.
Colors had a grayish cast, saturation was less than on the OEM lens, the
aperture ring was operated in the reverse direction of my Takumar's (Pentax
does it "backwards"), the front element turned when the focusing ring was
moved, making polarizer use difficult, the lens front element was not the
standard Takumar 49mm or 58mm, making it necessary to buy filters just for
use in that lens, and the resolution was noticeably less than that of the
OEM Takumar.

The build quality was obviously less-good than the OEM lens. The focusing
was not nearly as smooth, the zoom ring was a bit on the tight side, the
lens barrel was not as sturdy and the lens lacked multicoating (this was 30
years ago). So, while I saved a few dollars, I got pretty much what I paid
for and no more. I ended up putting that zoom lens up on the shelf, where
it remains to this day, and I bought only OEM lenses after that. They cost
a bit more, but the level of satisfaction that I derived from them made up
for the higher price. And not a single one of the OEM lenses has failed, in
3 decades.

British landscape photographer and author Brian Bower noted that, while his
Leica R zoom lenses cost a lot more than non-OEM lenses, he felt that they
were a good value because they retained their accuracy after over a decade
of hard use. He noted in one of his books that the cheaper zoom lenses
might see the elements go out of precise adjustment and the zoom mechanism
might become very loose after a time, making it necessary to keep checking
the zoom ring to be certain that the zoom ratio has not changed from
whatever it was originally set to. Bower valued consistently good results
more than lower price. He made his living with those tools, and he had
little tolerance for lens failures.

My own take on it is that if the proposed use of the lens is of a very
casual nature, it is probably okay to go for the savings. But if top
performance and reliability are paramount, one really has to think about
whether the savings might be offset by potential future loss from
poorly-performing equipment. I would rather have only a couple of really
good lenses than a kit full of lenses of questionable reliability and
performance. It seems that, in my own case, virtually every time I have
tried to save money by cutting corners I ended up paying double.



Cockpit Colin September 28th 05 09:03 PM


"Siddhartha Jain" wrote in message
ups.com...
Hi,

Given two lenses, one a prime (say 28mm) and the other a zoom (say
28-75mm) and both with an aperture of f2.8 -
- Will the prime be brighter than the zoom because it has fewer lens
elements?
- Will the prime be sharper wide open than the zoom at 28mm?

Ofcourse, a lot will depend on the particular makes and models being
compared but is there a rule of thumb?

- Siddhartha


I've heard it suggested that may high quality zooms are visually
indistinguishable from their prime equivalents - however both can usually
out-perform most photographers!




Tony Polson September 28th 05 09:49 PM

wrote:

The prime may be slightly brighter than the zoom, something which may
be more important in the motion-picture industry
They use a term called the "t stop" of a lens and it is a measure of
the light loss through a lens.
http://artsci-ccwin.concordia.ca/comm/lighting.htm
The difference could be as little as a third or as great as (or greater
than) a 2 stop difference between what the f-stop is and the t-stop,
while the DoF will be the same and sharpnes is likely to be less with a
zoom than a prime.


I would very much like to hear which particular lenses for DSLRs or
35mm SLRs produce a 2 stop reduction in illumination from that
expected at any given aperture.

You needn't list all of them, merely give some examples. ;-)

In real life still photography I don't believe it would be noticable
(the difference in brightness), because of a variety of factors.
I personally would not lose any sleep over it.


You wouldn't lose any sleep over a *two stop* reduction in
illumination? Either you are a very sound sleeper, or that reduction
simply doesn't exist. Or possibly both.

;-)

Tony Polson September 28th 05 09:52 PM

"Nostrobino" wrote:

It would be nice if this nonsensical misusage, which obviously is based on
someone's misunderstanding of the term some years ago (and then spread like
cancer through the power of the Internet) could be stamped out.


The use, or misuse, of the term "prime" is nothing new. The same
discussion was around in the 1960s and 70s. It wasn't resolved then
and probably never will be.

So don't blame the Internet. Blame the manufacturers who chose to use
this term as a marketing tool at various times in the last 50 years.

;-)


Dr. Joel M. Hoffman September 28th 05 10:47 PM

Given two lenses, one a prime (say 28mm) and the other a zoom (say
28-75mm) and both with an aperture of f2.8 -
- Will the prime be brighter than the zoom because it has fewer lens
elements?


No. f/2.8 tells you exactly how bright the lens is. (It's almost
like the old question about a pound of lead and a pound of feathers -
they do both weigh the same.)

- Will the prime be sharper wide open than the zoom at 28mm?


Probably, particuarly if both lenses are in the same price range. On
the other hand, there are lots of expensive zoom lenses that are
sharper than cheap fixed lenses.

-Joel

----------------------------------------------------------------------------
Free 35mm lens & digital camera reviews: http://www.exc.com/photography
----------------------------------------------------------------------------

BC September 29th 05 12:21 AM

"I would very much like to hear which particular lenses for DSLRs or
35mm SLRs produce a 2 stop reduction in illumination from that
expected at any given aperture."

2 stops is an awful lot, although I suppose some ancient zoom lenses
with lousy coatings might be that bad. One of the most complex zooms
I'm personally familiar with has about 40 elements, but nevertheless
suffers less than a 1-stop illumination reduction.

Brian


Eugene September 29th 05 12:24 AM

Yes, I'm sure the missuse of the term "prime lens" will go down in
history as one of the greatest tragedies of our generation ;-)

Zoom lenses ARE prime lenses, notwithstanding the now-popular misusage of
"prime."


Eugene September 29th 05 01:09 AM

You make it sound like it's some kind of disease. In the grand scheme of
things, does it really matter? Languages are dynamic, and the meanings
of words are constantly changing. The original meaning of "prime" in the
photographic sense is just an invention anyway. Referring to the
dictionary I find no mention of lenses as related to the meaning of the
word "prime". Who is therefore to decide which usage is correct? You
apparently!

The first listing that I found at dictionary.com is...

"First in excellence, quality, or value"

I think therefore it's perfectly reasonable to refer to a high quality
FFL lens in this way.

Perhaps you should just "chill out" a little and stop preaching about
who or who isn't ignorant.


Well, not necessarily, though of course the more people who misuse the term,
the harder it will be to correct it.

Most people do not want to use wrong terminology since it makes them look
ignorant. In the case of "prime" being used to mean FFL, this has only
spread because readers who have not seen the term before, and then see it
used by people they assume are knowledgeable, naturally adopt it themselves.
Thus newbies are caught up in the misusage and (perhaps partly because they
feel using jargon will make them look knowledgeable too), contribute to the
spread.

Some will continue to use it anyway, but others will drop it (and some have
dropped it) when the error is pointed out to them.

N.



[email protected] September 29th 05 01:31 AM

In message ,
"Cockpit Colin" wrote:

I've heard it suggested that may high quality zooms are visually
indistinguishable from their prime equivalents


You can always bring out the difference in a large print or display, or
with teleconverters or extension tubes

- however both can usually
out-perform most photographers!


Not under good conditions.
--


John P Sheehy


Eugene September 29th 05 01:45 AM

Just some links you may want to check out...

http://photonotes.org/cgi-bin/entry.pl?id=Primelens
http://en.wikipedia.org/wiki/Prime_lens
http://www.absoluteastronomy.com/enc...prime_lens.htm

Please stop spreading misinformation. The first usage of a term is not
necessarily the correct one. If you start referring to zooms as "prime"
you're just going to make yourself sound stupid. Whatever you think it
meant originally, is not what it means now.

Zoom lenses ARE prime lenses, notwithstanding the now-popular misusage of
"prime."

A prime lens is the camera lens as distinct from some other lens or
lenticular device (close-up lens, tele converter, etc.) used with it. It has
meant that since long before zoom lenses became commonplace, and therefore
no need to use another term to mean "non-zoom."

"Prime" is properly used in the sense of primary, main, chief or
original--all dictionary definitions for "prime."

There is NO dictionary definition for "prime" which means fixed focal length
or single focal length, or fixed or single anything else.

It would be nice if this nonsensical misusage, which obviously is based on
someone's misunderstanding of the term some years ago (and then spread like
cancer through the power of the Internet) could be stamped out. Surely "FFL"
is at least as easy to type as "prime" anyway, and there never was any
reason other than shortness to replace "fixed focal length" with the
incorrect term.

N.



Jeff R September 29th 05 01:59 AM


"Eugene" wrote in message
...
Just some links you may want to check out...

http://photonotes.org/cgi-bin/entry.pl?id=Primelens
http://en.wikipedia.org/wiki/Prime_lens
http://www.absoluteastronomy.com/enc...prime_lens.htm

Please stop spreading misinformation. The first usage of a term is not
necessarily the correct one. If you start referring to zooms as "prime"
you're just going to make yourself sound stupid. Whatever you think it
meant originally, is not what it means now.


Totally sick post, bro'! Hectic!
What a gay idea!



Randall Ainsworth September 29th 05 03:20 AM

In article . com,
Siddhartha Jain wrote:

Given two lenses, one a prime (say 28mm) and the other a zoom (say
28-75mm) and both with an aperture of f2.8 -
- Will the prime be brighter than the zoom because it has fewer lens
elements?
- Will the prime be sharper wide open than the zoom at 28mm?

Ofcourse, a lot will depend on the particular makes and models being
compared but is there a rule of thumb?


F/2.8 lets the same amount of light through regardless of the lens
design. F/2.8 is f/2.8.

Being from the old school, I would expect a fixed focal length lens to
be sharper than a zoom, but you may have to go to laboratory conditions
to prove it.

Peter September 29th 05 04:56 AM

Eugene wrote:
Just some links you may want to check out...

http://photonotes.org/cgi-bin/entry.pl?id=Primelens
http://en.wikipedia.org/wiki/Prime_lens
http://www.absoluteastronomy.com/enc...prime_lens.htm

Please stop spreading misinformation. The first usage of a term is not
necessarily the correct one.


No, but it can be good to distinguish between slang terminology
and standard terminology.

For instance, in audio people often talk about "acetate masters"
when they mean "lacquer originals." The slang terminology is
wrong on two counts because the originals of disc recordings
are made on cellulose nitrate lacquer and never acetate and they
are originals, not masters, according to long established terminology.
The use of the slang "acetate master" has caused very little real
confusion over the 70 years in which it has been in common use,
but it is still not correct because the disc is neither made
of acetate nor a master. (Wikipedia gets the definition of
"master recording" wrong, so I don't think it is a very good
source for standard technical vocabulary.)

An example in photography is the use of the word "macro"
as a synonym for "extreme close-up." Photomacrography,
from which we get "macro," has a very well established
technical meaning requiring the image size to be equal to
or larger than the object size. The Wikipedia article
"Macro Photography" starts out with the standard definition
which it calls the "classical definition" and then goes
on to discuss the extended use of the term in photographers'
slang without being particularly clear that the extended
meaning is still non-standard terminology. BTW it is better
to use "photomacrography" than "macro photography" since
"macrophotography" can mean the making of large photographs
by analogy with the difference between "photomicrography"
and "microphotography" which should never be confused with
each other.

The use of "prime lens" for "fixed focal length lens" appears
to originate in cinema where the need for a handy term
for a non-zoom lens was felt long before such a term was
needed in still photography. As a handy bit of slang, it
has much to recommend it: it is easy to say and quickly
understood. As a technical term, it has two major difficulties:
the word "prime" has little connection to what is meant,
and there was a prior use of the term in which the word
"prime" actually made sense.


If you start referring to zooms as "prime" you're just going
to make yourself sound stupid.


No, because you would always also be using an additional term
such as "supplementary lens" or "teleconverter" which would
supply the context which would make the meaning clear.


Whatever you think it meant originally, is not what it means now.


You know, sometimes words have two meanings.

Most of us can live with slang terminology and standard technical
terminology without getting particularly confused. Slang terminology
can be very handy: I'm not going to stop saying "Hypo" when I know
that fixer is actually thiosulphate. It isn't very likely that someone
will think I mean the actual chemical "sodium hyposulphite" AKA
"sodium hydrosulphite" which is AFAIK not used in photography.
But it is still good to distinguish between slang and proper technical
language. If I ordered "sodium hyposulphite" from a chemical supplier
who served dyers it is just possible I might get the wrong chemical.

Peter.
--



Peter September 29th 05 05:01 AM

Eugene wrote:
Just some links you may want to check out...

http://photonotes.org/cgi-bin/entry.pl?id=Primelens
http://en.wikipedia.org/wiki/Prime_lens
http://www.absoluteastronomy.com/enc...prime_lens.htm

Please stop spreading misinformation. The first usage of a term is not
necessarily the correct one.


No, but it can be good to distinguish between slang terminology
and standard terminology.

For instance, in audio people often talk about "acetate masters"
when they mean "lacquer originals." The slang terminology is
wrong on two counts because the originals of disc recordings
are made on cellulose nitrate lacquer and never acetate and they
are originals, not masters, according to long established terminology.
The use of the slang "acetate master" has caused very little real
confusion over the 70 years in which it has been in common use,
but it is still not correct because the disc is neither made
of acetate nor a master. (Wikipedia gets the definition of
"master recording" wrong, so I don't think it is a very good
source for standard technical vocabulary.)

An example in photography is the use of the word "macro"
as a synonym for "extreme close-up." Photomacrography,
from which we get "macro," has a very well established
technical meaning requiring the image size to be equal to
or larger than the object size. The Wikipedia article
"Macro Photography" starts out with the standard definition
which it calls the "classical definition" and then goes
on to discuss the extended use of the term in photographers'
slang without being particularly clear that the extended
meaning is still non-standard terminology. BTW it is better
to use "photomacrography" than "macro photography" since
"macrophotography" can mean the making of large photographs
by analogy with the difference between "photomicrography"
and "microphotography" which should never be confused with
each other.

The use of "prime lens" for "fixed focal length lens" appears
to originate in cinema where the need for a handy term
for a non-zoom lens was felt long before such a term was
needed in still photography. As a handy bit of slang, it
has much to recommend it: it is easy to say and quickly
understood. As a technical term, it has two major difficulties:
the word "prime" has little connection to what is meant,
and there was a prior use of the term in which the word
"prime" actually made sense.


If you start referring to zooms as "prime" you're just going
to make yourself sound stupid.


No, because you would always also be using an additional term
such as "supplementary lens" or "teleconverter" which would
supply the context which would make the meaning clear.


Whatever you think it meant originally, is not what it means now.


You know, sometimes words have two meanings.

Most of us can live with slang terminology and standard technical
terminology without getting particularly confused. Slang terminology
can be very handy: I'm not going to stop saying "Hypo" when I know
that fixer is actually thiosulphate. It isn't very likely that someone
will think I mean the actual chemical "sodium hyposulphite" AKA
"sodium hydrosulphite" which is AFAIK not used in photography.
But it is still good to distinguish between slang and proper technical
language. If I ordered "sodium hyposulphite" from a chemical supplier
who served dyers it is just possible I might get the wrong chemical.

Peter.
--



Brion K. Lienhart September 29th 05 06:17 AM

Eugene wrote:
You make it sound like it's some kind of disease. In the grand scheme of
things, does it really matter? Languages are dynamic, and the meanings
of words are constantly changing. The original meaning of "prime" in the
photographic sense is just an invention anyway. Referring to the
dictionary I find no mention of lenses as related to the meaning of the
word "prime". Who is therefore to decide which usage is correct? You
apparently!


It's pretty much established jargon in the photo industry. I've seen it
used in this sense since the mid-70s (when I started paying attention to
photo stuff). I hardly think it can be blamed solely on the internet.

Brion K. Lienhart September 29th 05 06:19 AM

Peter wrote:

You know, sometimes words have two meanings.

Most of us can live with slang terminology and standard technical
terminology without getting particularly confused. Slang terminology
can be very handy: I'm not going to stop saying "Hypo" when I know
that fixer is actually thiosulphate. It isn't very likely that someone


Not to be pedantic, but I think you mean "Jargon" not "Slang".

Brion K. Lienhart September 29th 05 06:23 AM

Dr. Joel M. Hoffman wrote:

Given two lenses, one a prime (say 28mm) and the other a zoom (say
28-75mm) and both with an aperture of f2.8 -
- Will the prime be brighter than the zoom because it has fewer lens
elements?



No. f/2.8 tells you exactly how bright the lens is. (It's almost
like the old question about a pound of lead and a pound of feathers -
they do both weigh the same.)


Well, no. The F-stop is the ratio of the aperature to the focal length,
which is constant regardless of the actual material(s) of the glass. In
the extreme case of spraying black paint on the lens, you could have an
F:2.8 lens with 0% light transmission.

Brion K. Lienhart September 29th 05 06:29 AM

Randall Ainsworth wrote:

In article . com,
Siddhartha Jain wrote:


Given two lenses, one a prime (say 28mm) and the other a zoom (say
28-75mm) and both with an aperture of f2.8 -
- Will the prime be brighter than the zoom because it has fewer lens
elements?
- Will the prime be sharper wide open than the zoom at 28mm?

Ofcourse, a lot will depend on the particular makes and models being
compared but is there a rule of thumb?



F/2.8 lets the same amount of light through regardless of the lens
design. F/2.8 is f/2.8.


Nope. F:2.8 is solely based on the size of the lens. Obsidian is glass,
you can grind it into a lens shape, but if you use it as an element in a
lens, you're going to get some reallllllly slow shutter speeds. Of
course that's an extreme case, the difference between plain old glass
glass, and exotic flouro-silicates is only a few fractions of a percent.

Eugene September 29th 05 07:38 AM

I don't think it has anything to do with the internet really. They've
been called prime lenses for as long as I can remember, and yes I do
pre-date the Internet ;-)

I certainly don't think it's some kind of fad. I suspect it would have
originated about the same time as zoom lenses. People needed a handy
term to distinguish their FFL lenses from the new zooms. FFL may be easy
and quick to write, but 'prime' is quicker to say. Also if we're going
to get pedantic about linguistics then why not take offence to the term
"zoom lens". Surely they should be called Variable Focal Length Lenses,
or VFL lenses. That's much better... Now we just have to re-educate all
the millions of poor ignorant fools using the incorrect terminology ;-)



It's pretty much established jargon in the photo industry. I've seen it
used in this sense since the mid-70s (when I started paying attention to
photo stuff). I hardly think it can be blamed solely on the internet.


Eugene September 29th 05 08:17 AM



The use of "prime lens" for "fixed focal length lens" appears
to originate in cinema where the need for a handy term
for a non-zoom lens was felt long before such a term was
needed in still photography. As a handy bit of slang, it
has much to recommend it: it is easy to say and quickly
understood. As a technical term, it has two major difficulties:
the word "prime" has little connection to what is meant,
and there was a prior use of the term in which the word
"prime" actually made sense.


OK, fair enough. You make a valid point, but in the case of "prime
lens", given the definition of the word, I don't think it's nescessarily
incorrect or ambiguous. Shortening complex expressions is just how
language works. Just a few other slang photographic terms I could think
of would be "film", or "sensor", or "flash", or even "lens". Everyone
knows what these terms mean, although none of them is strictly correct
or complete.



If you start referring to zooms as "prime" you're just going
to make yourself sound stupid.



No, because you would always also be using an additional term
such as "supplementary lens" or "teleconverter" which would
supply the context which would make the meaning clear.


Perhaps my comments were a bit harsh. I just took offense to the
suggestion that it was ignorant to use the widely accepted and
understood term "prime lens". It seemed clear that the Nostrobino was
just being undully pedantic and argumentative, and his comments added
nothing to the thread.



Whatever you think it meant originally, is not what it means now.



You know, sometimes words have two meanings.

Most of us can live with slang terminology and standard technical
terminology without getting particularly confused. Slang terminology
can be very handy: I'm not going to stop saying "Hypo" when I know
that fixer is actually thiosulphate. It isn't very likely that someone
will think I mean the actual chemical "sodium hyposulphite" AKA
"sodium hydrosulphite" which is AFAIK not used in photography.
But it is still good to distinguish between slang and proper technical
language. If I ordered "sodium hyposulphite" from a chemical supplier
who served dyers it is just possible I might get the wrong chemical.


As an Australian I certainly have no problem with slang ;-) Mind you
when I'm writing things for an international audience I'm careful to
avoid terms that will confuse people in other parts of the world. If I
wrote the way I would typically talk to other Aussies then a lot of
people wouldn't know what I was talking about. I hardly think though
that "prime lens" is one of those confusing obscure slang expressions.
Everyone knows what it means.

Tony Polson September 29th 05 09:21 AM

Eugene wrote:

I don't think it has anything to do with the internet really. They've
been called prime lenses for as long as I can remember, and yes I do
pre-date the Internet ;-)



If only it was as simple as referring to all fixed focal length lenses
as "prime" lenses. Most subscribers to this newsgroup probably aren't
old enough to recall that some manufacturers used the term "prime" to
refer to a high quality subset of their fixed focal length lenses.

What made a particular fixed focal length lens design a "prime" lens
was not clear. Why other fixed focal length lenses were not described
as "prime" lenses was even less clear. But what is clear is that
assuming all fixed focal length lenses were referred to as "prime"
lenses is wrong. It was marketing, pure and simple.

Since there is no accepted definition of a "prime" lens we should just
drop the term, as it serves only to confuse.

I like the idea of FFL and VFL, especially as so many VFL optics are
not true zooms because they do not hold focus when zoomed. They are
often termed vari-focal lenses (also "VFL"), which term could be
extended to include the true zooms.

FFL and VFL has my vote.

;-)


Eugene September 29th 05 10:08 AM

OK, I stand corrected. This does make sense. Actually now that I think
about it I don't tend to use the terms "prime" and "zoom" much anyway.
I'd nearly always just refer to the specific lens type. Like I'd just
say 50mm f1.4 rather than 50mm prime. Adding "prime" is kind of
redundant. If only one focal length lens is given then it's obvious I'm
not talking about variable focal length.

Also I think there would be very few situations where lumping everything
into 2 distinct groups would make sense. For example "zoom" could
equally refer to an EF-S 18-55, as it could to an EF 70-200 f2.8 L.
Aside from the fact that both lenses can change focal lengths, they
really have nothing much else in common. They serve entirely different
purposes and an entirely different market. Likewise "prime" (meaning
FFL) could equally refer to a 7mm circular fisheye, or a 1200mm
super-telephoto.

Grouping lenses by focal length ranges makes more sense, ultra-wide,
wide-angle, medium-telephoto, super-telephoto etc. FFL and VFL, while
correct and non-ambiguous are also I think too broad to be generally useful.

OK, well I wont use the term "prime" or "zoom" anymore as I can see that
they really don't add a lot of value.


If only it was as simple as referring to all fixed focal length lenses
as "prime" lenses. Most subscribers to this newsgroup probably aren't
old enough to recall that some manufacturers used the term "prime" to
refer to a high quality subset of their fixed focal length lenses.

What made a particular fixed focal length lens design a "prime" lens
was not clear. Why other fixed focal length lenses were not described
as "prime" lenses was even less clear. But what is clear is that
assuming all fixed focal length lenses were referred to as "prime"
lenses is wrong. It was marketing, pure and simple.

Since there is no accepted definition of a "prime" lens we should just
drop the term, as it serves only to confuse.

I like the idea of FFL and VFL, especially as so many VFL optics are
not true zooms because they do not hold focus when zoomed. They are
often termed vari-focal lenses (also "VFL"), which term could be
extended to include the true zooms.

FFL and VFL has my vote.

;-)


Tony Polson September 29th 05 10:15 AM

Eugene wrote:

Perhaps my comments were a bit harsh. I just took offense to the
suggestion that it was ignorant to use the widely accepted and
understood term "prime lens".



But "prime lens" is NOT a "widely accepted and understood term".

Because of the history of its use, it is essentially ambiguous. It
has only been used as a descriptor for all fixed focal length lenses
in recent times, and only by people who are unaware of its prior
usage, which was as a descriptor for a "high quality" subset of fixed
focal length lenses. You might be too young to recall this.

There was no accepted definition of which fixed focal length lenses
were "prime" and which were not. It was merely an attempt by
marketing people to promote some lenses as being "better" than others,
the implication being that one brand was "better" than another because
of the "high quality" of their "prime" lenses.

The terms "high quality", "better" and "prime" are all essentially
meaningless unless backed up with something more objective, repeatable
and reliable. As we all (should) know, comparisons between lenses are
qualitative at best.

The most commonly used "objective" comparator - MTF - was never
intended for making such comparisons. It was intended as an aid to
lens designers and nothing more. As a result it misleads far more
than it ever informs, and those who claim it is of any real value when
comparing photographic lenses are suffering from delusions.



Chris Brown September 29th 05 10:29 AM

In article ,
Tony Polson wrote:

Since there is no accepted definition of a "prime" lens we should just
drop the term, as it serves only to confuse.


Feel free to go ahead. The rest of the world will carry on using it. You're
tilting at windmills.

[email protected] September 29th 05 11:11 AM

On Wed, 28 Sep 2005 22:29:43 -0700, "Brion K. Lienhart"
wrote:

Randall Ainsworth wrote:

In article . com,
Siddhartha Jain wrote:


Given two lenses, one a prime (say 28mm) and the other a zoom (say
28-75mm) and both with an aperture of f2.8 -
- Will the prime be brighter than the zoom because it has fewer lens
elements?
- Will the prime be sharper wide open than the zoom at 28mm?

Ofcourse, a lot will depend on the particular makes and models being
compared but is there a rule of thumb?



F/2.8 lets the same amount of light through regardless of the lens
design. F/2.8 is f/2.8.


Nope. F:2.8 is solely based on the size of the lens. Obsidian is glass,
you can grind it into a lens shape, but if you use it as an element in a
lens, you're going to get some reallllllly slow shutter speeds. Of
course that's an extreme case, the difference between plain old glass
glass, and exotic flouro-silicates is only a few fractions of a percent.


So what was your point in bringing up a special case ulikely
to be implemented?

Jan Böhme September 29th 05 12:05 PM


skrev:

On Wed, 28 Sep 2005 22:29:43 -0700, "Brion K. Lienhart"
wrote:


F:2.8 is solely based on the size of the lens. Obsidian is glass,
you can grind it into a lens shape, but if you use it as an element in a
lens, you're going to get some reallllllly slow shutter speeds. Of
course that's an extreme case, the difference between plain old glass
glass, and exotic flouro-silicates is only a few fractions of a percent.


So what was your point in bringing up a special case ulikely
to be implemented?


To illustrate the difference in principle between f-stop and t-stop in
an obviuos way, perhaps?

Jan B=F6hme


Randall Ainsworth September 29th 05 01:44 PM

In article , Brion K. Lienhart
wrote:

Nope. F:2.8 is solely based on the size of the lens. Obsidian is glass,
you can grind it into a lens shape, but if you use it as an element in a
lens, you're going to get some reallllllly slow shutter speeds. Of
course that's an extreme case, the difference between plain old glass
glass, and exotic flouro-silicates is only a few fractions of a percent.


An f/2.8 lens is going to allow a specific amount of light to go
through regardless of what kind of glass it's made of.

no_name September 29th 05 01:50 PM

Nostrobino wrote:

"Siddhartha Jain" wrote in message
ups.com...

Nostrobino wrote:

Zoom lenses ARE prime lenses, notwithstanding the now-popular misusage of
"prime."

A prime lens is the camera lens as distinct from some other lens or
lenticular device (close-up lens, tele converter, etc.) used with it. It
has
meant that since long before zoom lenses became commonplace, and
therefore
no need to use another term to mean "non-zoom."

"Prime" is properly used in the sense of primary, main, chief or
original--all dictionary definitions for "prime."

There is NO dictionary definition for "prime" which means fixed focal
length
or single focal length, or fixed or single anything else.

It would be nice if this nonsensical misusage, which obviously is based
on
someone's misunderstanding of the term some years ago (and then spread
like
cancer through the power of the Internet) could be stamped out. Surely
"FFL"
is at least as easy to type as "prime" anyway, and there never was any
reason other than shortness to replace "fixed focal length" with the
incorrect term.


I am aware of the mis-usage of the term *prime* and so guilty of
propogating the mis-usage but I feel its time the FFL camp realised
that there is no turning back.



Well, not necessarily, though of course the more people who misuse the term,
the harder it will be to correct it.

Most people do not want to use wrong terminology since it makes them look
ignorant. In the case of "prime" being used to mean FFL, this has only
spread because readers who have not seen the term before, and then see it
used by people they assume are knowledgeable, naturally adopt it themselves.
Thus newbies are caught up in the misusage and (perhaps partly because they
feel using jargon will make them look knowledgeable too), contribute to the
spread.

Some will continue to use it anyway, but others will drop it (and some have
dropped it) when the error is pointed out to them.

N.



Just because "popular usage" may not appear in a particular dictionary
does not constitute "misuse".

If you speak of a prime lens to photographers, they know what you're
talking about.

Perhaps this should be continued in rec.english.language.anal.purists


no_name September 29th 05 01:57 PM

Tony Polson wrote:

Eugene wrote:

Perhaps my comments were a bit harsh. I just took offense to the
suggestion that it was ignorant to use the widely accepted and
understood term "prime lens".




But "prime lens" is NOT a "widely accepted and understood term".


Who here does not understand what is meant when the term "prime lens" is
used?

A show of hands please?

no_name September 29th 05 02:00 PM

John A. Stovall wrote:

On 28 Sep 2005 07:33:55 -0700, "Siddhartha Jain"
wrote:


Hi,

Given two lenses, one a prime (say 28mm) and the other a zoom (say
28-75mm) and both with an aperture of f2.8 -
- Will the prime be brighter than the zoom because it has fewer lens
elements?
- Will the prime be sharper wide open than the zoom at 28mm?

Ofcourse, a lot will depend on the particular makes and models being
compared but is there a rule of thumb?



Rule of Thumb: A prime at any focal length and wide open is better
than a zoom at any focal length wide open.


Except when it's not ... like a really well made fast zoom lens being
compared to a really poorly made slow prime lens.


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