Some basic questions about process lenses vs. "regular" lenses
 

I've never really understood the following -- maybe someone can
enlighten me:

1. What's the difference between "flat field" and curved field?" I
know that enlarger lenses and process lenses have "flat fields" -- but
what exactly does this mean? Is the subject-field flat -- or the
"image-field?" What's a non-flat field?

2. If process lenses are used for general photography (landscapes,
portraits, etc.), what is compromised or lost? If the answer is
"nothing," then why don't we all use process lenses for everything?

3. Reproduction ratios (may not be the corret term). Some lenses are
alleged to be "optimized" (whatever that means) for 1-to-1
reproduction. I assume that means that a 1-inch subect is rendered
as a 1-inch image on the film. Is that correct? What is the optimal
ratio for general photography lenses.

Thanks for any help.

Marco

Ron Wisner wrote an article entitled "The Myth of the Flat Field Lens" that
discusses most of these questions in some detail. See
http://wisner.com/myth.htm.


"Marco Milazzo" wrote in message
...
I've never really understood the following -- maybe someone can
enlighten me:

1. What's the difference between "flat field" and curved field?" I
know that enlarger lenses and process lenses have "flat fields" -- but
what exactly does this mean? Is the subject-field flat -- or the
"image-field?" What's a non-flat field?

2. If process lenses are used for general photography (landscapes,
portraits, etc.), what is compromised or lost? If the answer is
"nothing," then why don't we all use process lenses for everything?

3. Reproduction ratios (may not be the corret term). Some lenses are
alleged to be "optimized" (whatever that means) for 1-to-1
reproduction. I assume that means that a 1-inch subect is rendered
as a 1-inch image on the film. Is that correct? What is the optimal
ratio for general photography lenses.

Thanks for any help.

Marco

In article ,
Kirk Fry wrote:
There are two main problems with process lenses: 1) they are usually
huge and heavy (G clarons are an exception) and 2)Don't come and don't

You're kidding, right?

Because of their simple designs and small maximum apertures, most
process lenses are significantly smaller than most modern large format
taking lenses. A 19" Artar is significantly smaller than a 480mm
"general-purpose" plasmat; and, as another point of comparison, I have
used, over the years, as my standard 8x10 lens, a 14" Caltar (Commercial
Ektar copy), a 305mm Computar -- which is a plasmat process lens -- and
a 360mm Symmar-MC (which is almost exactly the same size as today's Apo
Symmar and Apo Rodagon).

Of all those lenses, the Comptar was by far the smallest, lightest, and
fit in the smallest shutter. In fact, of the lenses I own that cover
8x10, only the 180mm Protar V is smaller -- and *that* is an f/18 lens
in a Supermatic.

--
Thor Lancelot Simon
But as he knew no bad language, he had called him all the names of common
objects that he could think of, and had screamed: "You lamp! You towel! You
plate!" and so on. --Sigmund Freud

Kirk Fry wrote (in part):
There are two main problems with process lenses: 1) they are usually
huge and heavy (G clarons are an exception)

Why would that be? They are usually 4 element four group symmetrical (or
very nearly) air spaced lenses with maximum aperture f/9. I would expect
them to be smaller and lighter than a normal Plasmat f/5.6 of the same
focal length.

--
.~. Jean-David Beyer Registered Linux User 85642.
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/( )\ Shrewsbury, New Jersey http://counter.li.org
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Jean-David Beyer wrote in message ...
Kirk Fry wrote (in part):
There are two main problems with process lenses: 1) they are usually
huge and heavy (G clarons are an exception)

Why would that be? They are usually 4 element four group symmetrical (or
very nearly) air spaced lenses with maximum aperture f/9. I would expect
them to be smaller and lighter than a normal Plasmat f/5.6 of the same
focal length.

You're kidding, at least about lens design, aren't you?

I just took inventory of the process lenses I own.

6/2 double anastigmat: 240/9 G-Claron. Don't thump me about this
lens, that's what Schneider says it is and a count of reflections
agrees. Current G-Clarons are 6/4 Plasmats but older ones are Dagor
clones.

Tessar: 6"/9 Cooke Copying lens, tiny; 10.16"/9 Taylor Hobson Copying
lens, very small; 30 cm/9 Cooke Apotal, big enough to see.

Dialyte: 14"/10 Wray Apo-Process Lustrar Ser. II, large; 600/9 Apo
Ronar, huge, weighs about 8 pounds.

Four element double Gauss: 260/10 Process Nikkor, enormous.

Sort of Heliar (5/3, anyway): 180/10 and 360/10 Boyer Apo Saphirs,
both small.

More complex: 210/9 Konica Hexanon GRII, this lens is not a 6/4
Plasmat.

I appreciate that many Apo Artars and Apo Ronars, both dialyte types,
come to market and that some of my lenses are less common. Still and
all, it isn't safe to generalize about the category quite as broadly
as you did.

Cheers,

Dan

Jean-David Beyer wrote in message ...
Kirk Fry wrote (in part):
There are two main problems with process lenses: 1) they are usually
huge and heavy (G clarons are an exception)

Why would that be? They are usually 4 element four group symmetrical (or
very nearly) air spaced lenses with maximum aperture f/9. I would expect
them to be smaller and lighter than a normal Plasmat f/5.6 of the same
focal length.

You're kidding, at least about lens design, aren't you?

I just took inventory of the process lenses I own.

6/2 double anastigmat: 240/9 G-Claron. Don't thump me about this
lens, that's what Schneider says it is and a count of reflections
agrees. Current G-Clarons are 6/4 Plasmats but older ones are Dagor
clones.

Tessar: 6"/9 Cooke Copying lens, tiny; 10.16"/9 Taylor Hobson Copying
lens, very small; 30 cm/9 Cooke Apotal, big enough to see.

Dialyte: 14"/10 Wray Apo-Process Lustrar Ser. II, large; 600/9 Apo
Ronar, huge, weighs about 8 pounds.

Four element double Gauss: 260/10 Process Nikkor, enormous.

Sort of Heliar (5/3, anyway): 180/10 and 360/10 Boyer Apo Saphirs,
both small.

More complex: 210/9 Konica Hexanon GRII, this lens is not a 6/4
Plasmat.

I appreciate that many Apo Artars and Apo Ronars, both dialyte types,
come to market and that some of my lenses are less common. Still and
all, it isn't safe to generalize about the category quite as broadly
as you did.

Cheers,

Dan

In article ,
Dan Fromm wrote:

I appreciate that many Apo Artars and Apo Ronars, both dialyte types,
come to market and that some of my lenses are less common. Still and
all, it isn't safe to generalize about the category quite as broadly
as you did.

Nonetheless, the generalization that _does_ seem safe, to me at least
and I suspect to many others, is that for a lens of the same focal
length, a modern fast Plasmat is about as _large_ a lens as you're
going to get -- leaving older, lower-aperture lenses, especially f/9
or f/11 process lenses of any design, much smaller and lighter.

Earlier in this thread we had a comment about the size and weight of
a 1000mm Artar. This left me scratching my head wondering if the
person who wrote that had ever seen a 1000mm or even a 600mm "taking"
lens, whether a modern Plasmat or even an older Tessar type; either
is _much_, _much_ larger and heavier than a 1m Artar is.

--
Thor Lancelot Simon
But as he knew no bad language, he had called him all the names of common
objects that he could think of, and had screamed: "You lamp! You towel! You
plate!" and so on. --Sigmund Freud

In article ,
Dan Fromm wrote:

I appreciate that many Apo Artars and Apo Ronars, both dialyte types,
come to market and that some of my lenses are less common. Still and
all, it isn't safe to generalize about the category quite as broadly
as you did.

Nonetheless, the generalization that _does_ seem safe, to me at least
and I suspect to many others, is that for a lens of the same focal
length, a modern fast Plasmat is about as _large_ a lens as you're
going to get -- leaving older, lower-aperture lenses, especially f/9
or f/11 process lenses of any design, much smaller and lighter.

Earlier in this thread we had a comment about the size and weight of
a 1000mm Artar. This left me scratching my head wondering if the
person who wrote that had ever seen a 1000mm or even a 600mm "taking"
lens, whether a modern Plasmat or even an older Tessar type; either
is _much_, _much_ larger and heavier than a 1m Artar is.

--
Thor Lancelot Simon
But as he knew no bad language, he had called him all the names of common
objects that he could think of, and had screamed: "You lamp! You towel! You
plate!" and so on. --Sigmund Freud

Folks,

I agree it is not good to over generalize and I may have done that,
BUT I will stand on the generally huge part (obviously there are
exceptions as were pointed out). Let's start with one of the most
commonly availble process lens out there, a 19in Goerz red dot APO
Artar, a super duper optical performer. Almost always found in barrel
(the in shutter ones were special and cost real money). The one I have
weighs a bunch, not because of the glass but because it is mounted in
a heavy brass barrel (Goerz didn't discover aluminum until way late
just before they went bye bye). Then if you want it in a shutter you
have pay $300 or $400 for a #3 copal shutter and get it mounted for
another $400 (yes there is the Packard solution, another light weight,
small affair, or there is the lens cap trick). So what is the
compitition: A 450 M Nikkor in Compal #3, a bit smaller and lighter or
a Fujinon C450 f12 I think in Copol #1, way lighter. So what about
the 300 mm focal length. A 305 Apo Nikkor f9 copy lens is almost
always for sale on E bay. Again very samll glass and huge heavy mount
of brass. Again, very expensive to get mounted in a shutter. The
compition; a 300mm M Nikkor in Copal #1 or Fujinon makes a C lens that
is really small, also in 300mm focal length.

So, do you every wonder why these originally very expesive lenses that
are excellent optical preformers sell for pennies on the dollar on
ebay? Let me stand on my original hypothesis, Huge and Heavy and not
in Shutter.

The ones in shutter and which are not huge and heavy are not cheap.
Ya tend to get what you pay for. Have you noticed what 300mm
G-Clarons (plasmats by the way) sell for? Why is that?

And now let me close with the 300mm MC-Schneider f5.6 plasmat I own.
This one makes a 305mmm f9 Nikkor copy lens look like a midget. They
sell for pennies on the dollar compared to new prices, usually about
2X over what their copal 3 shutter is worth. Why do you suppose that
is? Anyone with any sense using 4X5 bought a 300mm M Nikkor and how
many folks are using 8X10 in the Studio any more? The huge and heavy
part killed that lens too.

In lenses, light weight and fast is good (along with a bunch of other
stuff), process lenses never had to be carried anywhere so the light
weight part was never even considered in the design.

Kirk


(Dan Fromm) wrote in message . com...
Jean-David Beyer wrote in message ...
Kirk Fry wrote (in part):
There are two main problems with process lenses: 1) they are usually
huge and heavy (G clarons are an exception)

Why would that be? They are usually 4 element four group symmetrical (or
very nearly) air spaced lenses with maximum aperture f/9. I would expect
them to be smaller and lighter than a normal Plasmat f/5.6 of the same
focal length.

You're kidding, at least about lens design, aren't you?

I just took inventory of the process lenses I own.

6/2 double anastigmat: 240/9 G-Claron. Don't thump me about this
lens, that's what Schneider says it is and a count of reflections
agrees. Current G-Clarons are 6/4 Plasmats but older ones are Dagor
clones.

Tessar: 6"/9 Cooke Copying lens, tiny; 10.16"/9 Taylor Hobson Copying
lens, very small; 30 cm/9 Cooke Apotal, big enough to see.

Dialyte: 14"/10 Wray Apo-Process Lustrar Ser. II, large; 600/9 Apo
Ronar, huge, weighs about 8 pounds.

Four element double Gauss: 260/10 Process Nikkor, enormous.

Sort of Heliar (5/3, anyway): 180/10 and 360/10 Boyer Apo Saphirs,
both small.

More complex: 210/9 Konica Hexanon GRII, this lens is not a 6/4
Plasmat.

I appreciate that many Apo Artars and Apo Ronars, both dialyte types,
come to market and that some of my lenses are less common. Still and
all, it isn't safe to generalize about the category quite as broadly
as you did.

Cheers,

Dan

Folks,

I agree it is not good to over generalize and I may have done that,
BUT I will stand on the generally huge part (obviously there are
exceptions as were pointed out). Let's start with one of the most
commonly availble process lens out there, a 19in Goerz red dot APO
Artar, a super duper optical performer. Almost always found in barrel
(the in shutter ones were special and cost real money). The one I have
weighs a bunch, not because of the glass but because it is mounted in
a heavy brass barrel (Goerz didn't discover aluminum until way late
just before they went bye bye). Then if you want it in a shutter you
have pay $300 or $400 for a #3 copal shutter and get it mounted for
another $400 (yes there is the Packard solution, another light weight,
small affair, or there is the lens cap trick). So what is the
compitition: A 450 M Nikkor in Compal #3, a bit smaller and lighter or
a Fujinon C450 f12 I think in Copol #1, way lighter. So what about
the 300 mm focal length. A 305 Apo Nikkor f9 copy lens is almost
always for sale on E bay. Again very samll glass and huge heavy mount
of brass. Again, very expensive to get mounted in a shutter. The
compition; a 300mm M Nikkor in Copal #1 or Fujinon makes a C lens that
is really small, also in 300mm focal length.

So, do you every wonder why these originally very expesive lenses that
are excellent optical preformers sell for pennies on the dollar on
ebay? Let me stand on my original hypothesis, Huge and Heavy and not
in Shutter.

The ones in shutter and which are not huge and heavy are not cheap.
Ya tend to get what you pay for. Have you noticed what 300mm
G-Clarons (plasmats by the way) sell for? Why is that?

And now let me close with the 300mm MC-Schneider f5.6 plasmat I own.
This one makes a 305mmm f9 Nikkor copy lens look like a midget. They
sell for pennies on the dollar compared to new prices, usually about
2X over what their copal 3 shutter is worth. Why do you suppose that
is? Anyone with any sense using 4X5 bought a 300mm M Nikkor and how
many folks are using 8X10 in the Studio any more? The huge and heavy
part killed that lens too.

In lenses, light weight and fast is good (along with a bunch of other
stuff), process lenses never had to be carried anywhere so the light
weight part was never even considered in the design.

Kirk


(Dan Fromm) wrote in message . com...
Jean-David Beyer wrote in message ...
Kirk Fry wrote (in part):
There are two main problems with process lenses: 1) they are usually
huge and heavy (G clarons are an exception)

Why would that be? They are usually 4 element four group symmetrical (or
very nearly) air spaced lenses with maximum aperture f/9. I would expect
them to be smaller and lighter than a normal Plasmat f/5.6 of the same
focal length.

You're kidding, at least about lens design, aren't you?

I just took inventory of the process lenses I own.

6/2 double anastigmat: 240/9 G-Claron. Don't thump me about this
lens, that's what Schneider says it is and a count of reflections
agrees. Current G-Clarons are 6/4 Plasmats but older ones are Dagor
clones.

Tessar: 6"/9 Cooke Copying lens, tiny; 10.16"/9 Taylor Hobson Copying
lens, very small; 30 cm/9 Cooke Apotal, big enough to see.

Dialyte: 14"/10 Wray Apo-Process Lustrar Ser. II, large; 600/9 Apo
Ronar, huge, weighs about 8 pounds.

Four element double Gauss: 260/10 Process Nikkor, enormous.

Sort of Heliar (5/3, anyway): 180/10 and 360/10 Boyer Apo Saphirs,
both small.

More complex: 210/9 Konica Hexanon GRII, this lens is not a 6/4
Plasmat.

I appreciate that many Apo Artars and Apo Ronars, both dialyte types,
come to market and that some of my lenses are less common. Still and
all, it isn't safe to generalize about the category quite as broadly
as you did.

Cheers,

Dan