APO enlarging lenses versus regular
PTakeuchi
Currently I own a 80mm f4 rodagon, and am wondering if the APO version of the
same lens will be sharper. Besides magnification differences, how does the 75mm
f4 APO compare with the 80mm APO? What about Schneider's APOs. I am printing
exclusively black and white negatives. The 50mm Rodagon APO I have is really
sharp and I am happy with it, but I don't know if spending $600 for a new 80 mm
APO is worth it.
Paul
Jean-David Beyer
PTakeuchi wrote:
I do not know if this applies to you, but most of the photographers whose work I
see would get sharper images by using a tripod, not a sharper camera or enlarger
lens.
--
Jean-David Beyer
Shrewsbury, New Jersey
Barry Sherman
PTakeuchi <ptak...@aol.com> wrote:
>Currently I own a 80mm f4 rodagon, and am wondering if the APO version of the
>same lens will be sharper. Besides magnification differences, how does the 75mm
>f4 APO compare with the 80mm APO? What about Schneider's APOs. I am printing
>exclusively black and white negatives. The 50mm Rodagon APO I have is really
>sharp and I am happy with it, but I don't know if spending $600 for a new 80 mm
>APO is worth it.
A few years ago I bought a bunch of medium format enlarging
lenses of APO and non-APO design and compared them side-by-side.
(I then returned all but the one that I chose as my prefered lens.)
I was using a rock solid enlarger (Durst L1000 bolted to the
studs in the wall) which I painstakingly aligned using a Salthill
Tri-linear alignment checker before the test. My Condit pin
registration negative carrier is a glass type. The enlarger table
was also bolted to the studs in the wall and I never touch the
enlarger table during printing, using utility tables placed alongside
the enlarging table to hold printing tools. Test prints were
small pieces of paper places at either a corner or in the center
and they were compared "blind" - I'd no idea while doing comparisons
which lens had made which print.
I compared an APO-Rodagon 80mm f/4, an APO-Componon 90mm f/4.5,
a Componon 80mm f/5.6, an El-Nikkor 80mm/f/5.6 and an El-Nikkor
75mm f/5.6 ( cheaper lens which I no longer see listed in the
catalogs).
My conclusion was that there differences in the center between
APO and non-APO lenses were negligible. This was printing at
a 20x24 print size from a 6x7 color transparency which was filled
with finicky detail and extremely sharp.
At the edges I found that the APO lenses were roughly one stop
sharper than the non-APO. What I mean by this is that I had to
stop the non-APO lenses down to f/11 in order to almost but not
quite equal the edge sharpness that I got with the APO lenses at f/8.
At f/8 the non-APO lenses had edge sharpness that was about the
same as the APO lenses had at f/5.6.
There was no perceptible difference in sharpness between the
non-APO lenses as a group or between the APO lenses. Except that
the El-Nikkor 75mm, being a cheaper lens, was noticibly less sharp
than any of the rest.
Previously I'd done a similar comparison between an APO-Componon
150mm f/4, an APO-Rodagon 150mm f/4 and an El-Nikkor 150mm f/5.6
and my results for the medium format lenses exactly paralleled
those for the large format lenses.
Basically, the consensus of opinion in this newgroup had always
reinforced my own experience - you won't find a significant difference
between APO lenses regardless of manufacturor or "model", nor will you
find significant differences between non-APO lenses regardless of
manufacturor or "model". They're all that good.
The real decision is whether it's worth the difference in price
between an APO and a non-APO lens to be able to achieve slightly
greater edge sharpness at the lens' optimum aperture and/or
to be able to achieve comparable edge sharpness with the APO with
the lens open one stop more than with the non-APO.
My decisions were that for large format, which is 98% of my
printing and for Ilfochrome, a very slow paper, which is 60% of my
printing, the extra stop of brightness was worthwhile and I kept the
APO-Componon 150mm f/4.
For me, for medium format and small formats, which, combined,
are perhaps 2% of my printing, I stuck with non-APO lenses.
(El-Nikkor 50mm f/2.8 and El-Nikkor 105mm f/5.6).
I'm very happy with my lenses.
Barry
--
Barry Sherman | Art does not reproduce what we see.
Suma Technologies, LLC | It makes us see. -- Paul Klee
My opinions, not Suma's |
Pat Fahey
>Basically, the consensus of opinion in this newgroup had always
>reinforced my own experience - you won't find a significant difference
>between APO lenses regardless of manufacturor or "model", nor will you
>find significant differences between non-APO lenses regardless of
>manufacturor or "model". They're all that good.
Agreed with one (huge) exception. The APO EL-Nikkors, most are now
special-order only, are heads above any others. You pay the price for that
perfection, though.
BobS
You might want to take a look at the graphs on the Schneider web site. You
can easily compare the advantages (or non-advantages) of the APO vs. non-apo
at several fstops. This is a Schenider only comparison, of course. Sure
taught me something though.
http://www.schneideroptics.com/
PTakeuchi wrote in message
<199804220235...@ladder01.news.aol.com>...
>Currently I own a 80mm f4 rodagon, and am wondering if the APO version of
the
>same lens will be sharper. Besides magnification differences, how does the
75mm
>f4 APO compare with the 80mm APO? What about Schneider's APOs. I am
printing
>exclusively black and white negatives. The 50mm Rodagon APO I have is
really
>sharp and I am happy with it, but I don't know if spending $600 for a new
80 mm
>APO is worth it.
>Paul
Bob Salomon
Rodenstock does NOT make a 75mm APO enlarging lens.
The Rodenstock Apo enlarging lenses are the 50mm, 80mm, 105mm and 150mm
APO Rodagon N series. All are labeled with the N.
Rodenstock makes many other Apo lenses and none are made for enlarging or
darkroom work.
There are the Apo Sironar N and S, the Apo Digital, the Apo Ronar and the
Apo Macro Sironar series.
There are also the lenses made specifically for duplication. The Apo
Rodagon D series. These are the 75mm 4.0, the 75mm 4.5 and the 120mm 5,6.
None of these 3 will do darkroom work, none are enlarging lenses, none
have pre set diaphragms, dis-engageable click stops or illuminated
diaphragms like Rodenstock's enlarging lenses.
Bob
--
PLEASE SEND ALL E-MAIL TO ME AT:
bobsa...@mindspring.com
HP MARKETING CORP. Gepe, Giottos, G-O light, Heliopan, Kaiser, Linhof, Pro Release, Rimowa, Rodenstock, Rollei, Sirostar
Alexander Selzer
BobS wrote:
> http://www.schneideroptics.com/
And you might also want to take a look at the site of Rodenstock
Praezisionsoptik GmbH http://www.rodenstockoptics.de/ or for America
Rodenstock Precision Optics, Inc. http://www.rodenstockoptics.com/
Alex
--
Alexander Selzer mailto:alexande...@gmx.de
Luc Novovitch
Jean-David Beyer wrote:
> but most of the photographers whose work I see would get sharper images by
> using a tripod, not a sharper camera or enlarger lens.
Yes, right, Professor. Try to put a poor quality lens on a poor quality
camera on your tripod, and show us the sharp result.
What does this have to do with the original posting? The guy is asking
for an advice on a lens, not a lecture on photography. I'm also
interested in answers, as I also would like to know the quality of the
apo Schneider lens he's mentioning. Good for you if you use a tripod.
The way I work (and I mean work, not Sunday photography), and my
subjects don't allow the use of a tripod. And I sure could use a
sharper lens in the darkroom. And talking of sharp images, would it be
great if the magic bullet would be the use of a tripod?
I suppose "most of the photographers whose work" you see use a $50.00
lens on their enlarger, shoot with a $100.00 camera, cut corners with
film, processing, enlarging paper, etc... What I mean is that ending up
with a sharp picture is no accident. But good skills backed up by GOOD
equipment, including sharp lenses in the darkroom. But gosh! I forgot!
You have a tripod....
--
Luc Novovitch
mailto:l...@ibm.net
JANIEP
Wow@!!,
<deep breath>
<shaking head>
This seems to be a bit of an over-reaction, Luc, to a helpful comment
from Jean-David. I'm not sure just why his comment 'pressed all your
buttons' and to tell you the truth, I don't care!
The forum should not be used to level such hostilities at a person who
clearly was merely trying to help out. If you felt his advice was not
useful to you, better to just ignore it rather than personally attack
him.
Jean-David's point was simply that many folks worry about lenses, and
films and cameras but fail to keep their cameras steady when they
finally press the shutter.
A simple point...innocent enough...helpful to some...obviously not to
you.
Have a happy day,
Jan
Howard
Couldn't agree more with you Jan. I only hope that Luc's vitriol
doesn't discourage Jean-David from continuing to try to be helpful.
I always find his comments interesting, if not useful.
<smile>
Howard
John Rogers
Good God, Luc. Did you just find out Darth Vader is your father?
What and uncalled for diatribe. Stupid and senseless too, as well
insulting and impolite.
Gregory A Kriss
> PTakeuchi wrote:
>
> > Currently I own a 80mm f4 rodagon, and am wondering if the APO version of the
> > same lens will be sharper. Besides magnification differences, how does the 75mm
> > f4 APO compare with the 80mm APO? What about Schneider's APOs. I am printing
> > exclusively black and white negatives. The 50mm Rodagon APO I have is really
> > sharp and I am happy with it, but I don't know if spending $600 for a new 80 mm
> > APO is worth it.
> > Paul
>
For what it's worth:
A few years back, when I was making a lot of 11x14 Cibas from 35mm
transparencies I had the following experiences:
Started using a 75mm f/4 ElNikkor with excellent results.
Tried an ApoRodagon but really didn't see much of a difference....
sometimes the ElNikkor images looked sharper than the Apo Rodagons and
visa-a-versa (have read that quality control with the ApoRodagons was a
problem but don't believe a word of it, also have read that the newer
ElNikkors are not as good as the older "all metal" ElNikkors... used
both side by side and can't see any difference in quality)
Finally in order to get a slightly larger Image on the easel I tried a
63mm f/2.8 ElNikkor and was amazed at the image quality. In the end I
used the 63mm ElNikkor for all my work simply because the images it
produced were superior to the 75mm ElNikkor and the ApoRodagon... and
the f/2.8 maximum aperture is a drean to focus.
Greg
Jean-David Beyer
Luc Novovitch wrote:
> Jean-David Beyer wrote:
>
> > but most of the photographers whose work I see would get sharper images by
> > using a tripod, not a sharper camera or enlarger lens.
>
> Yes, right, Professor. Try to put a poor quality lens on a poor quality
> camera on your tripod, and show us the sharp result.
Difficult or impossible, but most lenses these days are not that bad:
surprisingly good as a matter of fact. The images I see that are unsharp are
unsharp due to camera movement, not due to poor quality lenses.
> What does this have to do with the original posting?
The people I used to meet in camera clubs tended to be equipment buffs and often
had the latest and best equipment. Yet their images were often unsharp. No
matter how sharp your lens, if you need to shoot at 1/15 or 1/30 (as you usually
do here in New Jersey because it is usually overcast or just plain cloudy), you
will not get as sharp an image as even a 20 year old $50 enlarging lens is
capable of producing. I have no idea as to the technical ability and knowledge
of the original poster. I would be a pity for him to spend the money for the
more expensive lens and then get images no sharper than he did with his existing
equipment.
> The guy is asking
> for an advice on a lens, not a lecture on photography. I'm also
> interested in answers, as I also would like to know the quality of the
> apo Schneider lens he's mentioning. Good for you if you use a tripod.
> The way I work (and I mean work, not Sunday photography), and my
> subjects don't allow the use of a tripod. And I sure could use a
> sharper lens in the darkroom. And talking of sharp images, would it be
> great if the magic bullet would be the use of a tripod?
> I suppose "most of the photographers whose work" you see use a $50.00
> lens on their enlarger, shoot with a $100.00 camera, cut corners with
> film, processing, enlarging paper, etc...
No, most of them use fairly modern and quite expensive equipment, often better
than mine.
> What I mean is that ending up
> with a sharp picture is no accident.
At least we agree on something. But a chain is weaker than its weakest link, and
in my experience camera movement, not lens sharpness, is the limiting factor in
attaining sharp prints.
> But good skills backed up by GOOD
> equipment, including sharp lenses in the darkroom. But gosh! I forgot!
> You have a tripod....
>
> --
> Luc Novovitch
> mailto:l...@ibm.net
--
BobS
You directed your comments to the wrong person...I never mentioned
Rodenstock, that was the orginal poster, though I do use a 150mm APO S with
my large format camera and like it very much.
However I will point out that dealers such as B&H and Adorama advertise a
75/4 APO Rodenstock in their enlarging lens section. If this is incorrect
marketing than I think you should go infrom them. I really don't care
perosnally since I'm not in the market for any enlarging lens in the 75-80mm
range :).
Bob Salomon wrote in message ...
>Rodenstock does NOT make a 75mm APO enlarging lens.
>
>The Rodenstock Apo enlarging lenses are the 50mm, 80mm, 105mm and 150mm
>APO Rodagon N series. All are labeled with the N.
>
>Rodenstock makes many other Apo lenses and none are made for enlarging or
>darkroom work.
>
>There are the Apo Sironar N and S, the Apo Digital, the Apo Ronar and the
>Apo Macro Sironar series.
>
>There are also the lenses made specifically for duplication. The Apo
>Rodagon D series. These are the 75mm 4.0, the 75mm 4.5 and the 120mm 5,6.
>None of these 3 will do darkroom work, none are enlarging lenses, none
>have pre set diaphragms, dis-engageable click stops or illuminated
>diaphragms like Rodenstock's enlarging lenses.
>
dis-engagable click stops :).
>Bob
>
>In article <6hmpkv$8oo$1...@news.ncal.verio.com>, "BobS" <b...@psln.com> wrote:
>
>> You might want to take a look at the graphs on the Schneider web site.
You
>> can easily compare the advantages (or non-advantages) of the APO vs.
non-apo
>> at several fstops. This is a Schenider only comparison, of course. Sure
>> taught me something though.
>> http://www.schneideroptics.com/
>>
>> PTakeuchi wrote in message
>> <199804220235...@ladder01.news.aol.com>...
of
>> the
>> >same lens will be sharper. Besides magnification differences, how does
the
>> 75mm
>> >f4 APO compare with the 80mm APO? What about Schneider's APOs. I am
>> printing
>> >exclusively black and white negatives. The 50mm Rodagon APO I have is
>> really
>> >sharp and I am happy with it, but I don't know if spending $600 for a
new
>> 80 mm
>> >APO is worth it.
>> >Paul
>
Marc F. Hult
On Thu, 23 Apr 1998 12:58:42 -0500, Gregory A Kriss <kr...@nso1.uchc.edu> wrote
in message <353F81...@nso1.uchc.edu>:
>For what it's worth:
>
>A few years back, when I was making a lot of 11x14 Cibas from 35mm
>transparencies I had the following experiences:
>
>Started using a 75mm f/4 ElNikkor with excellent results.
>
>Tried an ApoRodagon but really didn't see much of a difference....
>sometimes the ElNikkor images looked sharper than the Apo Rodagons and
>visa-a-versa (have read that quality control with the ApoRodagons was a
>problem but don't believe a word of it, also have read that the newer
>ElNikkors are not as good as the older "all metal" ElNikkors... used
>both side by side and can't see any difference in quality)
>
>Finally in order to get a slightly larger Image on the easel I tried a
>63mm f/2.8 ElNikkor and was amazed at the image quality. In the end I
>used the 63mm ElNikkor for all my work simply because the images it
>produced were superior to the 75mm ElNikkor and the ApoRodagon... and
>the f/2.8 maximum aperture is a drean to focus.
>
Recognize that the four-element 75mm f4 El-Nikkor covers 6x6 so when printing
from 35mm, you avoid the corners which is where lens performance lags most. But
the current version (and probably previous ones) is optimized at 5X and
according to Nikon literature has a "usable magnification range" of 2X-10X. So
an 11x14" print from a 35mm original is outside Nikon's specification for this
lens. The 68mm f2.8 is optimized at 8X and usable 2-20X (like the 50mm f2.8).
In other words, the 63mm is designed for the enlargements you were making but
the 75mm is not even considered to be "usable" by Nikon at the magnification you
were in fact using.
HTH ... Marc
--
Marc F. Hult
hu...@cinternet.net
Frank Calidonna
Luc Novovitch wrote:
>
> Yes, right, Professor. Try to put a poor quality lens on a poor quality
> camera on your tripod, and show us the sharp result.
> What does this have to do with the original posting? The guy is asking
> for an advice on a lens, not a lecture on photography. I'm also
> interested in answers, as I also would like to know the quality of the
> apo Schneider lens he's mentioning. Good for you if you use a tripod.
> The way I work (and I mean work, not Sunday photography), and my
> subjects don't allow the use of a tripod. And I sure could use a
> sharper lens in the darkroom. And talking of sharp images, would it be
> great if the magic bullet would be the use of a tripod?
> I suppose "most of the photographers whose work" you see use a $50.00
> lens on their enlarger, shoot with a $100.00 camera, cut corners with
> film, processing, enlarging paper, etc... What I mean is that ending up
> with a sharp picture is no accident. But good skills backed up by GOOD
> equipment, including sharp lenses in the darkroom. But gosh! I forgot!
> You have a tripod....
>
Many pose questions here to find information, answers to problems, and
wisdom from all the members of this group. A few, such as JD, put a
great deal of time and effort into helping and sharing with people -
overtime actually. Your hostile response to a helpful answer, whether it
met your specific needs or not, was totally unwarranted. Not at all in
keeping with the spirit of this group.
Ignoring for the moment. with great difficulty, the tone of your post I
will say that, as a teacher and photographer, I have been shown hundreds
of unsharp photographs and the vast majority were due to camera
movement. The old adages about tripods are as valid now as they ever
were. Computer formulated lenses (most of them) generally produce very
good results. Yes a $300 enlarging lens is superior to a $50 lens as
long as the camera did not shake during exposure. The differece between
a high end lens and an apo lense probably exists in a range you cannot
even see. Like having a stereo the produces 25,000hz, but only your dog
can hear it.
Please think hard before posting angry note. They add nothing useful and
do a great deal of harm.
Frank Rome,NY
Richard Knoppow
Frank Calidonna <frank.c...@worldnet.att.net> wrote:
>Luc Novovitch wrote:
>
>>
>> Yes, right, Professor. Try to put a poor quality lens on a poor quality
>> camera on your tripod, and show us the sharp result.
>> What does this have to do with the original posting? The guy is asking
>> for an advice on a lens, not a lecture on photography. I'm also
& etc....
>
>Please think hard before posting angry note. They add nothing useful and
>do a great deal of harm.
>
> Frank Rome,NY
BRAVO Frank
---
Richard Knoppow
Los Angeles, Ca.
dick...@ix.netcom.com
Eberhard Funke
On Thu, 23 Apr 1998 13:09:47 -0700, "BobS" <b...@psln.com> wrote:
------<snip>-------
Sorry I would like to add a note to the preceeding post which I had
missed:
>Bob Salomon wrote in message ...
>>Rodenstock does NOT make a 75mm APO enlarging lens.
>>
>>The Rodenstock Apo enlarging lenses are the 50mm, 80mm, 105mm and 150mm
>>APO Rodagon N series. All are labeled with the N.
>>
>>Rodenstock makes many other Apo lenses and none are made for enlarging or
>>darkroom work.
>>
-------<snip>--------
I have an Apo-Rodagon 1:4 90mm enlarging lense which I bought about 10
years ago. It is not labeled N.
--
Eberhard
Michael Liczbanski
Frank Calidonna wrote in message <6hol1a$q...@bgtnsc03.worldnet.att.net>...
>. Yes a $300 enlarging lens is superior to a $50 lens as
>long as the camera did not shake during exposure.
FWIW:
Well...no, it isn't. The resulting picture will be unsharp when produced
from a unsharp negative with any lens, that's all.
A good "$300.00" enlarging lens will give you:
- corner-to-corner grain sharpness, whereas a lousy lens will not. This is
what you focus on, right, the grain?
- no linear center -Vs.-corners distortion (again, a bad lens will distort
the image and individual grains)
- good contrast (again a bad lens will probably not give you that.)
- color correction and lack of focusing problems associated with the
chromatic aberration.
So the goal is to pick a lens that allows maintaining corner-to-corner grain
sharpness with your film format, at a reasonably wide working f/stop, at
your desired magnification. (Ah, and don't forget to keep the
negative/lens/baseboard parallel, and your negative flat. Then pick a
lens. )
Of course, - a good lens is only worth its price when used with an aligned
enlarger that doesn't oscillate (shake) during exposure. I suspect, that a
good look at some (most?, 50-50?) unsharp prints will reveal the enlarger
shake, rather than the unsharp negative.
Other possible culprits of unsharp prints are:
- focus shift with different f/stop (so focus at your working aperture)
- focus shift due to VC filters (focus with the VC filter in place and
refocus if changing the filter)
- keeping the grain focuser on a different plane that the paper (put a piece
of your enlarging paper under the focuser)
And so it goes...
Michael
Bob Salomon
The 90mm Apo Rodagon was replaced by the 80mm Apo Rodagon which was
replaced by the current Apo Rodagon N series.
That is why yours is not labeled an N. It isn't one.
Bob
In article <6hpj8r$c0f$1...@news02.btx.dtag.de>, Eberhar...@t-online.de
(Eberhard Funke) wrote:
--
David F. Stein
All good points. But what about the flatness of the enlarging easel
itself. Like the film holders in view camera work, this has always
seemed like one of the weak links in an otherwise sophisticated system.
Sincerely,
David Stein
A-H...@worldnet.att.net
Frank Calidonna wrote:
>
> Luc Novovitch wrote:
>
> >
> > Yes, right, Professor. Try to put a poor quality lens on a poor quality
> > camera on your tripod, and show us the sharp result.
> > What does this have to do with the original posting? The guy is asking
> > for an advice on a lens, not a lecture on photography. I'm also
> do a great deal of harm.
>
> Frank Rome,NY
*.*
Richard J. Fateman
In article <1d806m0.1bj...@det-mi15-01.ix.netcom.com>,
David F. Stein <dfs...@ix.netcom.com> wrote:
>All good points. But what about the flatness of the enlarging easel
>itself. Like the film holders in view camera work, this has always
>seemed like one of the weak links in an otherwise sophisticated system.
>
>Sincerely,
>David Stein
>
Not so much of an issue as all that. You are likely to have enough
depth of field at normal enlarging distances, assuming the baseboard
is approximately level. Depth of focus is much more critical, which
is why the negative should be kept flat in the enlarger, and why the
sheet film in view cameras are potentially a weak link.
I suspect that a more important criterion for easels than flatness per
se is that they hold the paper absolutely steady. Some paper has a
tendency to sag, curl, etc. during a long exposure.
--
Richard J. Fateman
fat...@cs.berkeley.edu http://http.cs.berkeley.edu/~fateman/
Michael Liczbanski
Yeah, this is a good point. Everything should be parallel, including the
easel and the surface on which the easel is parked (be it the baseboard, a
table or a moveable shelf system.) These flimsy cork or rubber "feet" on
easels have always been frustrating.
There are other considerations as well - for instance paper flatness,
building shake, voltage shifts, dusty/dirty optical stages of the enlarger
itself, etc.
One needs to be a careful darkroom worker...Difficult if the setup is not
permanent.
Michael
David F. Stein wrote in message
<1d806m0.1bj...@det-mi15-01.ix.netcom.com>...
>All good points. But what about the flatness of the enlarging easel
>itself. Like the film holders in view camera work, this has always
>seemed like one of the weak links in an otherwise sophisticated system.
>
>Sincerely,
>David Stein
>
>
>
>Michael Liczbanski <removethis....@email.msn.com> wrote:
>
>> A good "$300.00" enlarging lens will give you:
>> - corner-to-corner grain sharpness, whereas a lousy lens will not. This
is
PTakeuchi
Does anybody have a table comparing different lens manufacturers's enlarging
lenses and their optimum magnifications?
PTakeuchi
Maybe I should rephrase my original question. Assuming the enlarger is aligned
and the negative is well-exposed and sharp, how do the 75-90 mm enlarging
lenses stack up for black and white enlarging to say 16x20, an 8-10X
magnification given a 6x6 negative? How do the Nikors fare against the
Rodenstocks and Schneiders, both APO and regular?
Paul
Bob Salomon
In article <199804271943...@ladder01.news.aol.com>,
jc1...@aol.com (JC17FL) wrote:
> x-no-archive: yes
>
> APO vs regular lenses ?
>
> Here's my question:
>
> I've always heard that enlarging/printing paper is sensitive to blue or yellow
> light mainly (VC paper?)...
>
> So why would I need a super, duper APO glass which focuses red, green,
blue (or
> whatever the 3 colors are) so perfectly & precisely if the paper is only going
> to be sensitive to colors that an APO glass is only going to focus perfectly
> one of ???
>
> Just use a regular lens.
>
> Joseph.
AN APO lens does several things. One of the most important is to reduce
color fringing. In black and white this results in fine lines being
reproduced thinner than with a non Apo lens.
In our case (Rodenstock) the Apo lenses are optimized for a greater
reproduction range than the non Apos, have a wider range of optimal
apertures, hit the optiml aperture sooner and are multi coated to reduce
flare and improve contrast.
All of these benefits are equally important for color and B&W printing.
Bob
Richard Knoppow
jc1...@aol.com (JC17FL) wrote:
>x-no-archive: yes
>
>APO vs regular lenses ?
>
>Here's my question:
>
>I've always heard that enlarging/printing paper is sensitive to blue or yellow
>light mainly (VC paper?)...
>
>So why would I need a super, duper APO glass which focuses red, green, blue (or
>whatever the 3 colors are) so perfectly & precisely if the paper is only going
>to be sensitive to colors that an APO glass is only going to focus perfectly
>one of ???
>
>Just use a regular lens.
>
>Joseph.
Its not so much the color correction as overall correction. The
ability to make fast apo's is due to the availability of optical
glases with favorable index of refraction vs: dispersion
characteristics. It is possible to reduce the radius of curvature of
the surfaces with these glasses for a given power. Most aberrations
are minimized by this reduction so the same special glass which allows
the more complete color correction also allows better correction of
other faults. So it is possible for a modern apo to have better
performance even when used with only a limited range of colors.
OTOH, this difference may be very small when compared to a modern
achromat (corrected for two colors) lens. The best apo's have better
performance at a given stop than cheaper lenses. This may be
important when working with processes which are slow. This
improvement will be mainly in the corners of the image.
As has been said here many times getting the best out of a good lens
depends on everything else being well aligned as well as being free
from vibration.