Schneider Symmar's

[AArDvarK]

As far as less costly lenses go on the used market,
older Symmar convertibles and the later "S" type,
were either one apochromatic?

And what was the "S" improvement about? Was it
a supreme difference?

Thanks all,

Alex

[Tom]

S was single focal length. The old convertable Symmars compromised the design to
give better performance with the partial lens. Symmar S's were designed to give
better correction when using both elements. Early Symmar S's were single coated,
later ones multi-coated.

Apo's? I think they are only apochromatic in the advertising agency's mind, but
having never having used one that is hearsay only. The Apo Symmar is the newest
version.

--

AArDvarK wrote:
> As far as less costly lenses go on the used market,
> older Symmar convertibles and the later "S" type,
> were either one apochromatic?
>
> And what was the "S" improvement about? Was it
> a supreme difference?
>
> Thanks all,
>
> Alex
>
>

[Nicholas]

AArDvarK wrote:
> As far as less costly lenses go on the used market,
> older Symmar convertibles and the later "S" type,
> were either one apochromatic?
>
> And what was the "S" improvement about? Was it
> a supreme difference?
>
> Thanks all,
>
> Alex
>
>
The Symmar was designed to be a convertible lens, the Symmar S is not...
Apparently the "S" is based on the Symmar but designed and modified not
to be used as a convertible lens and therefore improved for standard
use. From this article I am reading right now by Kramer in 1976 Modern
Photography, the improvement, in terms of image sharpness--is definate.
I know I used to own a Symmar which couldn't get a sharp image no matter
what I did (no flames please, my experience only).

[Bruce Jones]

I bought a used Symmar 180mm f/5.6 convertible several years ago.
Made some photographs with it, but it was not crispy sharp, and the
shutter was sluggish. Shadows were also cloudy, with little detail.
After looking closely at the lens elements with a bright light behind
it, there was a film on some of the internal elements. Sent it to
Schneider in New York for cleaning. They were very prompt and
thorough. The lens was over 20 years old when I bought it, according
to the Schneider web site serial number log.

When the lens came back, it was very clean, with no visible gunk on
the internal elements and the shutter worked perfectly, even in low
temps. The photographs made thereafter were crisp and sharp, with no
noticeable flare even in direct sunlight. Deep shadows, clean
highlights and no visible flare. Overall center to edge coverage is
excellent on 4x5 film, even with significant shift/rise/fall
adjustments. With the 6x9 120 back, I can almost tear the bellows
with adjustments and see no fall off in coverage in the outer edges of
the image. It appears to have a multi coating, and flare in direct
sunlight is not an issue as long as a decent lens shade is used. I
use a flexible, square Lee Filters shade that cost a lot, but is worth
every penny.

To Schneider's credit (and my gratitude), they even marked the lens
barrel for f/64 and f/90 above the f/45 marked during manufacture. I
am quite impressed and happy with this lens, and would buy another one
in a heartbeat.

Have not tried it after cleaning with the front lens group removed to
increase the focal length to 315mm, but it was not very sharp in early
trials before cleaning. It is interesting, however, to use a 315mm
lens with a 6x9 120 film back on the view camera.

A Kodak publication on Large Format Photography mentioned that
convertible lenses were sharpest at or near minimum apertures. After
using the Symmar for table top product photography from f/8 to f/45, I
have not been able to see any difference in sharpness at any aperture
setting, using visual inspection with high quality 4x and 10x loupes
on a light table, or with drum and flat bed scans of 4x5 Ektachrome
transparencies at high resolutions.

We finally have cable modem service in our <hood> but have not changed
my e-mail address in this forum. If you would like to discuss
anything more about the joys of large format photography, please
e-mail me at: .

Best regards and Happy Easter!

Bruce aka Opusstuf

"AArDvarK" > wrote in message news:<Wundc.369$Va4.149@fed1read01>...
> As far as less costly lenses go on the used market,
> older Symmar convertibles and the later "S" type,
> were either one apochromatic?
>
> And what was the "S" improvement about? Was it
> a supreme difference?
>
> Thanks all,
>
> Alex

[P. MacGahan]

"AArDvarK" > wrote in message news:<Wundc.369$Va4.149@fed1read01>...
> As far as less costly lenses go on the used market,
> older Symmar convertibles and the later "S" type,
> were either one apochromatic?
>
> And what was the "S" improvement about? Was it
> a supreme difference?
>
> Thanks all,
>
> Alex

I don't believe that Schneider ever claimed that the Symmar-S was
apochromatic. I only tried a 210mm Symmar-S and found it good. I
didn't compare it with a Symmar, though. Subsequently, there are
Multicoated Symmar-Ss. That is probably a further improvement.

Several have mentioned that quality control seems to improve with time
at Schneider and others. Also, with a more recent design, it might be
easier to get a history of the particular lens that convinces you that
damage hasn't been concealed.

Still, both types are not the latest. With any lens, one test is better
than opinions.

[CamArtsMag]

As far as less costly lenses go on the used market,
older Symmar convertibles and the later "S" type,
were either one apochromatic?

And what was the "S" improvement about? Was it
a supreme difference?

Thanks all,

Alex

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

View Camera published a two part article on Schneider lenses about a year ago.
The series traced the history and evolution of these lenses.

There is no way I can summarize such an article down to a paragraph or two. If
you are intrerested in gettign the back issues let me know.

steve simmons

[jjs]

In article >,
(CamArtsMag) wrote:

> As far as less costly lenses go on the used market,
> older Symmar convertibles and the later "S" type,
> were either one apochromatic?
>
> And what was the "S" improvement about? Was it
> a supreme difference?

>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> [... snip usual advertisment ...]
>
> There is no way I can summarize such an article down to a paragraph or two. If
> you are intrerested in gettign the back issues let me know.

He posed two simple questions. He didn't ask for a tome, a history of
Schneider, you moron. You have all the answers, so ANSWER HIS SIMPLE
QUESTIONS with a simple answer or two. Make a contribution here!

[David Nebenzahl]

On 4/10/2004 10:06 AM jjs spake thus:

> In article >,
> (CamArtsMag) wrote:
>
>> As far as less costly lenses go on the used market,
>> older Symmar convertibles and the later "S" type,
>> were either one apochromatic?
>>
>> And what was the "S" improvement about? Was it
>> a supreme difference?
>
>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>> [... snip usual advertisment ...]
>>
>> There is no way I can summarize such an article down to a paragraph or two. If
>> you are intrerested in gettign the back issues let me know.
>
> He posed two simple questions. He didn't ask for a tome, a history of
> Schneider, you moron. You have all the answers, so ANSWER HIS SIMPLE
> QUESTIONS with a simple answer or two. Make a contribution here!

Apparently the talented publisher of the celebrated large-format magazine has
suddenly lost his ability to summarize and condense information. But hey, you
can *BUY HIS MAGAZINE* and read all about it!


--
.... but never have I encountered a guy who could not be bothered
to make his own case on his own show.

- Eric Alterman on his appearance on Dennis Miller's bomb of a show
on CNBC (3/17/04)

[Alecj]

Hey, JJS, I don't think the questions were simple at all. [Question #1 had
already been answered - Q #2 isn't clear]. Steve gave him a source for
info.

People are just too damned lazy these days to do a little work on their own
to inform themselves. Who knows, he just might learn something in the
process.

Besides, who the hell knows what "supreme difference" means anyway? Do you?

You said: "Make a contribution here!", so if you're so d****d smart, answer
it yourself.



"jjs" > wrote in message
...
> In article >,
> (CamArtsMag) wrote:
>
> > As far as less costly lenses go on the used market,
> > older Symmar convertibles and the later "S" type,
> > were either one apochromatic?
> >
> > And what was the "S" improvement about? Was it
> > a supreme difference?
>
> >
> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > [... snip usual advertisment ...]
> >
> > There is no way I can summarize such an article down to a paragraph or
two. If
> > you are intrerested in gettign the back issues let me know.
>
> He posed two simple questions. He didn't ask for a tome, a history of
> Schneider, you moron. You have all the answers, so ANSWER HIS SIMPLE
> QUESTIONS with a simple answer or two. Make a contribution here!

[jjs]

In article >, "Alecj"
> wrote:

> Hey, JJS, I don't think the questions were simple at all. [Question #1 had
> already been answered - Q #2 isn't clear]. Steve gave him a source for
> info.

Downright embarassing to see a grown man kiss SS's ass in public. Killfile!

[AArDvarK]

> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>
> View Camera published a two part article on Schneider lenses about a year ago.
> The series traced the history and evolution of these lenses.
>
> There is no way I can summarize such an article down to a paragraph or two. If
> you are intrerested in gettign the back issues let me know.
>
> steve simmons
>
----------------------------

Gosh Steve, I ordered that article on film holders
and how restore wooden ones, three weeks ago,
was charged as in the bank statement, and it has
STILL not arrived ...

you tell me.

Alex

[AArDvarK]

> Hey, JJS, I don't think the questions were simple at all. [Question #1 had
> already been answered - Q #2 isn't clear]. Steve gave him a source for
> info.
>
> People are just too damned lazy these days to do a little work on their own
> to inform themselves. Who knows, he just might learn something in the
> process.
>
> Besides, who the hell knows what "supreme difference" means anyway? Do you?
>
> You said: "Make a contribution here!", so if you're so d****d smart, answer
> it yourself.

Rediculous, the question is "supremely" obvious. Other
than that, that is all SS does ... he offers something for sale
and never any genuine help as is done in a news group.

Alex

[AArDvarK]

> The Symmar was designed to be a convertible lens, the Symmar S is not...
> Apparently the "S" is based on the Symmar but designed and modified not
> to be used as a convertible lens and therefore improved for standard
> use. From this article I am reading right now by Kramer in 1976 Modern
> Photography, the improvement, in terms of image sharpness--is definate.
> I know I used to own a Symmar which couldn't get a sharp image no matter
> what I did (no flames please, my experience only).
>

That is interesting, but I would guess they really wanted
to quell the market by not selling two focal length lenses
in one. The convertible Symmar could have easily been
re-engineered to be "more symmetricaly corrected", it
was named "Symmar" in the first place, as is the point
of the design. They probably already had the better design
on the shelves.

As far as lens formulas and money go, try to imagine
a tiny sized Zeiss Tessar (protar?) design, in barrel, that
can cover a 20x24" frame, even at an F-stop fast enough
for focusing and photography. They did it! long ago but
the only reason they don't now is marketing. That lens
would be too cheap to produce for what it can do (and
maybe not all that symmetrical). But most anything can
be done with lens formulas.

Alex

[Ivan Kuturcockoff]

In article >,
(jjs) wrote:

> Downright embarassing to see a grown man kiss SS's ass in public. Killfile!

Pot, Kettle, Black.

[Richard Knoppow]

"AArDvarK" > wrote in message
news:Wundc.369$Va4.149@fed1read01...
>
> As far as less costly lenses go on the used market,
> older Symmar convertibles and the later "S" type,
> were either one apochromatic?
>
> And what was the "S" improvement about? Was it
> a supreme difference?
>
> Thanks all,
>
> Alex
>
No Schneider Symmars, including the current "apo" lenses
are true apochromats although they may be very well
corrected for color. Apochromatic is a formal term in
optics, it means a lens which is corrected for simultaneous
focus of three colors, and correction of spherical
aberration for two colors. The color correction is gotten by
the choice of glass types by the designer. While
apochromatic correction is no gurantee of improved
performance most apochromats are special purpose lenses with
great care given to their overall design.
German standards allow the use of the abbreviation APO for
lenses that are well corrected for color even though they
are acromats (corrected for only two colors). This is
unfortunate and leads to considerable confusion and
unnecessary controversey.
The old chrome barrel convertible Symmar is a very good
lens, often sold cheap on the used market. The later,
non-convertible version is a better lens because its design
is not compromised to make it convertible. Nonetheless, the
front or rear cell can be used alone at small stops with
decent image quality.


--
---
Richard Knoppow
Los Angeles, CA, USA

[Largformat]

Subject: Re: Schneider Symmar's
From: (jjs)
Date: 4/10/2004 11:06 AM Mountain Daylight Time
Message-id: >

In article >,
(CamArtsMag) wrote:

> As far as less costly lenses go on the used market,
> older Symmar convertibles and the later "S" type,
> were either one apochromatic?
>
> And what was the "S" improvement about? Was it
> a supreme difference?

>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> [... snip usual advertisment ...]
>
> There is no way I can summarize such an article down to a paragraph or two.
If
> you are intrerested in gettign the back issues let me know.

He posed two simple questions. He didn't ask for a tome, a history of
Schneider, you moron. You have all the answers, so ANSWER HIS SIMPLE
QUESTIONS with a simple answer or two. Make a contribution here!
>>>>>>>>>>>>>>>>>>>>

and where in this response is an answer to his questions? At least I gave him a
place to go. All you did is come one with your name calling and hostility.

steve simmons

[jjs]

In article >,
(Largformat) wrote:

> [...]
> At least I gave him a place to go.

Quit tempting me with good straight lines.

[David Nebenzahl]

On 4/11/2004 8:37 AM jjs spake thus:

> In article >,
> (Largformat) wrote:
>
>> [...]
>
>> At least I gave him a place to go.
>
> Quit tempting me with good straight lines.

Ba da BOOM (tish!)


--
My coffee was beginning to wear off and with it the momentary illusion
it gives that things are Right and life is Good.

- James Thurber, from the short story _The Black Magic of Barney Haller_

[AArDvarK]

> No Schneider Symmars, including the current "apo" lenses
> are true apochromats although they may be very well
> corrected for color. Apochromatic is a formal term in
> optics, it means a lens which is corrected for simultaneous
> focus of three colors, and correction of spherical
> aberration for two colors. The color correction is gotten by
> the choice of glass types by the designer. While
> apochromatic correction is no gurantee of improved
> performance most apochromats are special purpose lenses with
> great care given to their overall design.
> German standards allow the use of the abbreviation APO for
> lenses that are well corrected for color even though they
> are acromats (corrected for only two colors). This is
> unfortunate and leads to considerable confusion and
> unnecessary controversey.
> The old chrome barrel convertible Symmar is a very good
> lens, often sold cheap on the used market. The later,
> non-convertible version is a better lens because its design
> is not compromised to make it convertible. Nonetheless, the
> front or rear cell can be used alone at small stops with
> decent image quality.
>
>
> --
> ---
> Richard Knoppow

Mr. Knoppow what about the Rodenstock APO Sironar lenses,
are they true APO's?
Alex

[Bob Salomon]

In article <sErfc.6612$432.248@fed1read01>,
"AArDvarK" > wrote:

> > No Schneider Symmars, including the current "apo" lenses
> > are true apochromats although they may be very well
> > corrected for color. Apochromatic is a formal term in
> > optics, it means a lens which is corrected for simultaneous
> > focus of three colors, and correction of spherical
> > aberration for two colors. The color correction is gotten by
> > the choice of glass types by the designer. While
> > apochromatic correction is no gurantee of improved
> > performance most apochromats are special purpose lenses with
> > great care given to their overall design.
> > German standards allow the use of the abbreviation APO for
> > lenses that are well corrected for color even though they
> > are acromats (corrected for only two colors). This is
> > unfortunate and leads to considerable confusion and
> > unnecessary controversey.
> > The old chrome barrel convertible Symmar is a very good
> > lens, often sold cheap on the used market. The later,
> > non-convertible version is a better lens because its design
> > is not compromised to make it convertible. Nonetheless, the
> > front or rear cell can be used alone at small stops with
> > decent image quality.
> >
> >
> > --
> > ---
> > Richard Knoppow
>
> Mr. Knoppow what about the Rodenstock APO Sironar lenses,
> are they true APO's?
> Alex

The true meaning of apochromatic in photography is that the lateral
color correction of the secondary spectrum is corrected to within a
small percentage of the focal length of the lens. This assures that
color aberations , such as ghosting, are eliminated.
Rodenstock, Schneider, Leica manufacture to this definition.

For professionals using a microscope the definition states thaat the
primary rays meet at a common point.

--
To reply no_ HPMarketing Corp.

[AArDvarK]

> > Mr. Knoppow what about the Rodenstock APO Sironar lenses,
> > are they true APO's?
> > Alex
>
> The true meaning of apochromatic in photography is that the lateral
> color correction of the secondary spectrum is corrected to within a
> small percentage of the focal length of the lens. This assures that
> color aberations , such as ghosting, are eliminated.
> Rodenstock, Schneider, Leica manufacture to this definition.
>
> For professionals using a microscope the definition states thaat the
> primary rays meet at a common point.

Yes I understand your meaning, and in RK's earlier reply
he states that the APO Schneider's are not* true APO's.
You should read it. I think that for Schneider to legalize
the term "APO" when they are not, is strictly marketing
hype. The meaning of my question is, "is Rodenstock
doing the same thing?"

Alex

[Martin Jangowski]

AArDvarK > wrote:

> Yes I understand your meaning, and in RK's earlier reply
> he states that the APO Schneider's are not* true APO's.
> You should read it. I think that for Schneider to legalize
> the term "APO" when they are not, is strictly marketing
> hype. The meaning of my question is, "is Rodenstock
> doing the same thing?"

On Paul Butzi's page <http://www.butzi.net> are several
data sheets of Rodenstock lenses. As far as I've seen,
none of the "Apo" lenses show the typical curve with
three crossings of the zero-line at the "Longitudinal
color abberation" diagram. They all have only
two crossings typical for a achromatic lens.

Martin

[AArDvarK]

> On Paul Butzi's page <http://www.butzi.net> are several
> data sheets of Rodenstock lenses. As far as I've seen,
> none of the "Apo" lenses show the typical curve with
> three crossings of the zero-line at the "Longitudinal
> color abberation" diagram. They all have only
> two crossings typical for a achromatic lens.
>
> Martin

"Irony ... the mystery of all things indeed"

Yeah! I saw it right after replying to Bob's reply
while doing a search for "Rodenstock" we have
Bob and his rodenstock page at HP marketing,
then Rodenstock the eye glasses company, no
lenses there, and the Rodenstock photographic
lens maker is now a Linos group company!
http://www.linos.com/en/produkte_rdst.html

For the sake of Nicodemus's festering forlock...

And there it is, Bob sent those charts to Paul Butzi: http://www.butzi.net/rodenstock/rodenstock.htm
In any case, I don't know the terminology that
it takes to read those charts, unfortunatly. Do
you mean these charts might be saying that these
lenses are not* truly APO, and are at the same
level as Schneider's?

Alex

[jjs]

In article <s_vfc.8060$432.5820@fed1read01>, "AArDvarK"
> wrote:

> In any case, I don't know the terminology that
> it takes to read those charts, unfortunatly. Do
> you mean these charts might be saying that these
> lenses are not* truly APO, and are at the same
> level as Schneider's?

Are there ANY TRUE APOs in the world, and if there were would they be
suitable for general LF work (which means not flat-art, and not just work
significantly closer then infinity) ???

Would a 'real' APO really be significantly better than an adequate LF
lens? Are we not splitting hairs?

IMHO it's manufacturing quality control that is at issue with lenses. The
variations between individual lenses is more daunting to me than finding
'the best' in terms of categorical optical-bench ideals.

It seems to me that most relatively new LF users would get finer results
if they learned to focus and expose properly before they criticized the
lens they use.

[Bob Salomon]

In article >,
(jjs) wrote:

> In article <s_vfc.8060$432.5820@fed1read01>, "AArDvarK"
> > wrote:
>
> > In any case, I don't know the terminology that
> > it takes to read those charts, unfortunatly. Do
> > you mean these charts might be saying that these
> > lenses are not* truly APO, and are at the same
> > level as Schneider's?
>
> Are there ANY TRUE APOs in the world, and if there were would they be
> suitable for general LF work (which means not flat-art, and not just work
> significantly closer then infinity) ???
>
> Would a 'real' APO really be significantly better than an adequate LF
> lens? Are we not splitting hairs?
>
> IMHO it's manufacturing quality control that is at issue with lenses. The
> variations between individual lenses is more daunting to me than finding
> 'the best' in terms of categorical optical-bench ideals.
>
> It seems to me that most relatively new LF users would get finer results
> if they learned to focus and expose properly before they criticized the
> lens they use.

Yes Rodenstock and Schneider Apo lenses and fully meet the definition of
Apo as set by D.I.N. (the people who write the standards that the German
lens manufacturers produce to. The specific standard they meet is DIN
19040 part 5.

This is also the definition of an apochromatic lens as defined by the
Photonics Dictionary for optical purchasing agents.

Yes the traditional old timers keep referring to the 3 colors crossing
at a common point. And that is true for lenses used for microscopes.

But not for photography lenses.

Now the current DIN specification assures that the lateral chromatic
aberrations in the secondary spectrum, are reduced to a minute
percentage (not more than o,4% of the focal length at 1:1) of the focal
length. This results in better images with no color fringing around
objects. The elimination of fringing results in finer lines and better
resolution. This is true for B&W as well as color.

You would be far better off not debating the number of angels on the
head of a pin - since the traditionalist do not agree with the standards
used for the past several decades - and doing some test shooting to see
the differences.

Take an Apo Sironar S and a Symmar S and go shoot a scene with fine
detail at the edges (tree limbs with twigs against the sky, and compare
results). You see the difference - Buy the S. You don't - buy the old
lens.

But debating this won't make you a better photographer, shooting will.
Just be aware of the benefits of the Apo lens and decide for yourself if
that benefit is worthwhile. For you.

--
To reply no_ HPMarketing Corp.

[AArDvarK]

jjs ... getting "tired of it all" ?

[jjs]

"Bob Salomon" > wrote in message
...

> Yes Rodenstock and Schneider Apo lenses and fully meet the definition of
> Apo as set by D.I.N. (the people who write the standards that the German
> lens manufacturers produce to. The specific standard they meet is DIN
> 19040 part 5.

Very good to learn, Bob. It is heartening that they follow their
manufacturing ideals as far as the Germans do in making Beer.

> You would be far better off not debating the number of angels on the
> head of a pin [... snip good part ...]

All I know about angels would _fit_ on the head of a pin. (Beware - I
majored in Philosphy at Oxford.)

Thank you for pointing out the distinction between the old and new
conventions. That's important.

[David Nebenzahl]

On 4/15/2004 9:44 AM jjs spake thus:

> "Bob Salomon" > wrote in message
> ...
>
>> You would be far better off not debating the number of angels on the
>> head of a pin [... snip good part ...]
>
> All I know about angels would _fit_ on the head of a pin. (Beware - I
> majored in Philosphy at Oxford.)

So, I take it you're a master debater?


--
I was quickly apprised that an "RSS feed" was not, as I had naively
imagined, some new and unspeakable form of sexual debauchery practised
by young persons of dubious morality, but a way of providing news
articles to the cybernetic publishing moguls of the World Wide Wait so
they can fill the airwaves with even more useless drivel.

- Cynical shop talk from comp.publish.prepress

[David Nebenzahl]

On 4/15/2004 8:10 AM AArDvarK spake thus:

> jjs ... getting "tired of it all" ?

Ah, my naive friend. You need to do a bit of rooting around in the musty
archives of this newsgroup to gain a better understanding of why this
particular stinking rotting dead horse is still being flogged.

This is a long-standing dispute, primarily between Bob Salomon on the one hand
representing marketroids (aka scum of the Earth) in general, and anyone else
on the other hand who actually knows their stuff about optics. (This dispute
is a pretty good illustration of the old spiritual adage, "Those who say don't
know, and those who know don't say".)

If you think you're the one to bring Mr. Salomon to his senses, I hate to
break it to you, but you ain't the first to try.


--
I was quickly apprised that an "RSS feed" was not, as I had naively
imagined, some new and unspeakable form of sexual debauchery practised
by young persons of dubious morality, but a way of providing news
articles to the cybernetic publishing moguls of the World Wide Wait so
they can fill the airwaves with even more useless drivel.

- Cynical shop talk from comp.publish.prepress

[brian]

Bob Salomon > wrote in message >...
> In article >,
> (jjs) wrote:
>
> > In article <s_vfc.8060$432.5820@fed1read01>, "AArDvarK"
> > > wrote:
> >
> > > In any case, I don't know the terminology that
> > > it takes to read those charts, unfortunatly. Do
> > > you mean these charts might be saying that these
> > > lenses are not* truly APO, and are at the same
> > > level as Schneider's?
> >
> > Are there ANY TRUE APOs in the world, and if there were would they be
> > suitable for general LF work (which means not flat-art, and not just work
> > significantly closer then infinity) ???
> >
> > Would a 'real' APO really be significantly better than an adequate LF
> > lens? Are we not splitting hairs?
> >
> > IMHO it's manufacturing quality control that is at issue with lenses. The
> > variations between individual lenses is more daunting to me than finding
> > 'the best' in terms of categorical optical-bench ideals.
> >
> > It seems to me that most relatively new LF users would get finer results
> > if they learned to focus and expose properly before they criticized the
> > lens they use.
>
> Yes Rodenstock and Schneider Apo lenses and fully meet the definition of
> Apo as set by D.I.N. (the people who write the standards that the German
> lens manufacturers produce to. The specific standard they meet is DIN
> 19040 part 5.
>
> This is also the definition of an apochromatic lens as defined by the
> Photonics Dictionary for optical purchasing agents.
>
> Yes the traditional old timers keep referring to the 3 colors crossing
> at a common point. And that is true for lenses used for microscopes.
>
> But not for photography lenses.
>
> Now the current DIN specification assures that the lateral chromatic
> aberrations in the secondary spectrum, are reduced to a minute
> percentage (not more than o,4% of the focal length at 1:1) of the focal
> length. This results in better images with no color fringing around
> objects. The elimination of fringing results in finer lines and better
> resolution. This is true for B&W as well as color.
>
> You would be far better off not debating the number of angels on the
> head of a pin - since the traditionalist do not agree with the standards
> used for the past several decades - and doing some test shooting to see
> the differences.
>
> Take an Apo Sironar S and a Symmar S and go shoot a scene with fine
> detail at the edges (tree limbs with twigs against the sky, and compare
> results). You see the difference - Buy the S. You don't - buy the old
> lens.
>
> But debating this won't make you a better photographer, shooting will.
> Just be aware of the benefits of the Apo lens and decide for yourself if
> that benefit is worthwhile. For you.

Symmetry alone can achieve perfect lateral color correction at 1:1 in
a lens which is not even achromatic. The DIN spec is nonsense, and
would not be acceptable to anyone I know in the lens design/optics
community.

Brian
www.caldwellphotographic.com

[brian]

(jjs) wrote in message >...

>
> Are there ANY TRUE APOs in the world, and if there were would they be
> suitable for general LF work (which means not flat-art, and not just work
> significantly closer then infinity) ???
>
> Would a 'real' APO really be significantly better than an adequate LF
> lens? Are we not splitting hairs?
>
> IMHO it's manufacturing quality control that is at issue with lenses. The
> variations between individual lenses is more daunting to me than finding
> 'the best' in terms of categorical optical-bench ideals.
>
> It seems to me that most relatively new LF users would get finer results
> if they learned to focus and expose properly before they criticized the
> lens they use.

I've seen some Artar type designs that actually are apochromatic -
that is with three crossings in the axial color curve. I'm not sure
if actual Artar or Ronar process lenses have this level of correction,
however. As far as I know, none of the currently manufactured large
format lenses are apochromatic. The "apo" sironar/symmars certainly
are not. For most purposes it does not matter.

It is possible to design a Plasmat having true apochromatic
correction, but unless you do extensive work in the infrared or
ultraviolet you would probably not notice much improvement. A true
large format apochromat could be put to very good use if you
photograph artwork at discrete wavelengths over a large waveband, for
example.

Apochromatic correction is pretty much independent of field curvature
correction. Also, symmetrical or quasi-symmetrical apochromats will
generally retain true apochromatic correction regardless of
magnification. The aberration that typically restricts the
magnification range of a large format lens is coma.

Another area where true apochromatic correction is highly desirable is
with long focal length lenses which must have extremely good
correction. Examples range from broadcast zoom lenses to large
refracting telescopes. People might be surprised that zooms can be
apochromatic, but its a fact that the zoom lens with the worlds
largest zoom range (300:1) is also a true apochromat with three color
crossings in the longer focal lengths. And in case Bob is reading,
this is *not* a microscope objective!!

Brian
www.caldwellphotographic.com

[jjs]

"brian" > wrote in message
m...

> Symmetry alone can achieve perfect lateral color correction at 1:1 in
> a lens which is not even achromatic. The DIN spec is nonsense, and
> would not be acceptable to anyone I know in the lens design/optics
> community.
>
> Brian
> www.caldwellphotographic.com

Now I'm really confused. When you say 1:1, do you mean original image size
to rendered film image size? If that's what you mean, how would that apply
to general LF photography?

[AArDvarK]

Bob, the DIN is German created, they can, I am sure,
create any standard they want as national* for the purpose
of MARKETING, maybe we should all take a look at
the exact ISO of what apochromatic is? The German
point in doing so is a bit obvious, which is that it is more
than likely that it is more expensive to make true APO
lenses (to the exact science of it) than to make achromats
and simply call them APO's. They are lying (only my
suspicion at my level of knowledge).

Alex

[AArDvarK]

That kind salesmanship as a forthright mentality is like
the tinsel on an artificial christmas tree, rediculous.
"DIN" standards, please ...

Alex

[Bob Salomon]

In article <1nFfc.8103$432.4878@fed1read01>,
"AArDvarK" > wrote:

> Bob, the DIN is German created, they can, I am sure,
> create any standard they want as national* for the purpose
> of MARKETING, maybe we should all take a look at
> the exact ISO of what apochromatic is? The German
> point in doing so is a bit obvious, which is that it is more
> than likely that it is more expensive to make true APO
> lenses (to the exact science of it) than to make achromats
> and simply call them APO's. They are lying (only my
> suspicion at my level of knowledge).
>
> Alex

Fine. Try this then:

"


Defining Apochromatism



by Thomas Back




With the proliferation of apochromatic refractors that are available
to the amateur astronomer, it is time to define the parameters of a
true apochromatic lens.

The modern definition of "apochromat" is the following:

An objective in which the wave aberrations do not exceed 1/4 wave
optical path difference (OPD) in the spectral range from C (6563A -
red) to F (4861A - blue), while the g wavelength (4358A - violet) is
1/2 wave OPD or better, has three widely spaced zero color crossings
and is corrected for coma.

Here is a more detailed analysis for those that are interested. The
term "Apochromat" is loosely used by many manufacturers and amateurs
astronomers. Let's look at the history of the definition, and maybe a
more modern one. Ernst Abbe, in 1875, met and worked for Carl Zeiss,
a small microscope, magnifier and optical accessory company. They
realized that they needed to find improved glass types, if they were
going to make progress with the optical microscope. In 1879, Abbe met
Otto Schott. Together they introduce the first abnormal dispersion
glasses under the name of Schott and Sons.

Abbe discovered that by using optically clear, polished natural
fluorite, in a microscope objective, that apochromatism could be
achieved. These first true apochromatic microscope objectives were so
superior to the competition, that Zeiss gained nearly the entire high
end market.

So secret was the use of fluorite, that Abbe marked an "X" on the
data sheet for the fluorite element, so as to keep it secret from the
other optical companies. Abbe's definition of apochromatism was the
following.

Apochromat: an objective corrected parfocally for three widely spaced
wavelengths and corrected for spherical aberration and coma for two
widely separated wavelengths.

This definition is not as simple as it sounds. I have designed
thousands of lenses: simple achromats, complex achromats, semi-apos,
apochromats, super-achromats, hyper-achromats, and Baker
super-apochromats. Abbe's definition, to put it in clearer terms (I
hope) is that a true apochromat is an objective that has three color
crossings that are spaced far apart in the visual spectrum (4000A,
deep violet to 7000A, deep red). However, just because a lens has
three color crossings, doesn't mean that it is well corrected. Let's
say that a 4" lens has three color crossings at the F, e and C
wavelengths (4861A, 5461A and 6563A). Fine, this objective is now
considered an apochromat because it has three color crossings in the
blue, green and red. But what about the level of spherical aberration
at each of these wavelengths? If the lens is 2 waves overcorrected at
4861A, and 1.5 waves undercorrected at 6563A, is it still an
apochromat? No. It is no better than an achromat, as the OPD
wavefront error is worse than a 4" f/15 achromat. Abbe, in his
definition of apochromat, states that spherical aberration must be
corrected for two widely spaced wavelengths.

Now I can tell you what happens when you correct spherical for two
widely spaced wavelengths; you correct for all the wavelengths
between them too. This is called correcting for spherochromatism (the
variation of spherical aberration with a change in wavelength). Only
with extremely long focal lengths, aspherics, large air spaces, or a
combination of the three, can you correct for this aberration.

It is the designer that must come up with a good compromise of color
correction, lack of spherical aberration (3rd order and zonal) and
control spherochromatism, so as not to degrade the image contrast. Al
Nagler used a wide air-spaced Petzval design with Fluorite and
Lanthanum glass in his TV-140 to control the above aberrations.
Roland Christen uses the highest quality super ED glass (FPL-53) and
specially matched crowns to control the various aberrations (he also
slightly aspherizes the outer surfaces). TMB Optical uses Russian
OK-4 super ED glass (similar to FPL-53) with an outer crown and a
special dense crown glass, using air spacing with different internal
radii to control the above aberrations.

Also, the Abbe condition of coma correction is overstated, that is,
if a lens is well corrected for coma at one wavelength, in almost all
cases it will be corrected for coma at all the visual wavelengths.

Now you might ask, what is a modern definition of apochromatism?
Well, you might begin with three color crossings, but you would be
wrong. One of the first things an optical designer discovers is that
with catalog glass data, it is easy to design lenses with three or
even four color crossings (super-achromat). But when you get 6 place
or greater melt data, these designs often breakdown to only two or
three color crossings (that is not to say that a 4 color crossing
objective cannot be made), albeit with the chromatic focal shift
being very small. What is really important is how small the chromatic
focal shift is (not the zero crossings) over a wide spectral range,
and how low the spherical aberration is over that same range. So we
are left with quite an ambiguous definition.

After designing, testing and selling many different apochromatic
lenses I can state this: There is no "definite" line where a lens
becomes apochromatic (in the world of commercial APO lenses). But any
lens, be it a doublet, triplet, air-spaced or Petzval, that has a
peak visual null (~5550A - the green-yellow) with a Strehl ratio of
..95 or better, coma corrected and is diffraction limited from C (red)
to F (blue) with 1/4 wave OPD spherical or better, spot sizes under
the diffraction limit (about 10 microns in an f/8 system), has good
control of the violet g wavelength with no more than 1/2 wave OPD P-V
spherical and a spot size no larger than about 3x the diffraction
limit, will satisfy the modern definition of "Apochromatism."

Lenses of this quality do not satisfy the Abbe definition, but for
all intents and purposes, will be color free and will give extremely
sharp and contrasty images.

Thomas Back
TMB Optical"

--
To reply no_ HPMarketing Corp.

[brian]

"jjs" > wrote in message >...
> "brian" > wrote in message
> m...
>
> > Symmetry alone can achieve perfect lateral color correction at 1:1 in
> > a lens which is not even achromatic. The DIN spec is nonsense, and
> > would not be acceptable to anyone I know in the lens design/optics
> > community.
> >
> > Brian
> > www.caldwellphotographic.com
>
> Now I'm really confused. When you say 1:1, do you mean original image size
> to rendered film image size? If that's what you mean, how would that apply
> to general LF photography?

1:1 means unit magnification, i.e. the image is the same size as the
object. The point I was making was that any symmetrical lens will
automatically be corrected for lateral color at 1:1 magnification.
Bob's "apo" definition talks about reducing *lateral* color at 1:1.
By this definition even a lens with primary chromatic aberration (i.e.
not even achromatic) could be called "apo".

Therefore, its absolutely ludicrous to define "apo" by talking about
lateral color at 1:1.

To be honest, because I work as a professional lens designer I
probably get alot more upset than most people when I see marketeers
and others suck the meaning out of a well established optical term.

Brian
www.caldwellphotographic.com

[jjs]

In article >,
(brian) wrote:

>[... snip important stuff ... see the post]

> To be honest, because I work as a professional lens designer I
> probably get alot more upset than most people when I see marketeers
> and others suck the meaning out of a well established optical term.

Okay, I'm aligned. You know, I'm just going to take pictures and forget
all this stuff until/if I am unhappy with the resolution I am getting.
Given how long I've been going on like this, I'll never ask again.

Thanks, Brian.

[AArDvarK]

Now THAT is a good lesson, and a serious understanding, Bob!
His writing suggests it is genuinly impossible to create a true
apochromatic lens anyway, because of natural production
circumstances (for shorter lenses). I still do not have the
understanding tech-wise but some things are obvious. I still
would like to know what you know of the genuine APO quality
differences between Rodenstock and Schneider, if you know
of any, even if you are the distributer of Rodenstock. Are you
also the importer?

Alex

[Bob Salomon]

In article <yPZfc.9888$432.4706@fed1read01>,
"AArDvarK" > wrote:

> Now THAT is a good lesson, and a serious understanding, Bob!
> His writing suggests it is genuinly impossible to create a true
> apochromatic lens anyway, because of natural production
> circumstances (for shorter lenses). I still do not have the
> understanding tech-wise but some things are obvious. I still
> would like to know what you know of the genuine APO quality
> differences between Rodenstock and Schneider, if you know
> of any, even if you are the distributer of Rodenstock. Are you
> also the importer?
>
> Alex

The distributor is always the importer. All distributors have contracts
with the factories they represent.

Both Rodenstock and Schneider manufacture to meet the DIN standards. As
for the difference between lens lines, well we both have literature and
published charts and graphs that are your for the asking. Even the
pre-publication version of the new digital lens brochure.

--
To reply no_ HPMarketing Corp.