Leica Apo-Summicron-R 90 f/2 ASPH, SUMMILUX-R 80 mm f/1.4, APO-SUMMICRON-R 90 mm f/2 ASPH, APO-MACRO-ELMARIT 100 mm f/2.8 User Manual

Leica R-Lenses

August 2003
Chapter 2: 80 mm and 100 mm lenses

__ LEICA SUMMILUX-R 80 mm f/1.4
__ LEICA APO-SUMMICRON-R 90 mm f/2 ASPH.
__ LEICA APO-MACRO-ELMARIT 100 mm f/2.8

by Erwin Puts

Chapter 2

Leica R-Lenses

1

In older textbooks about photographic techniques there is
much space devoted to the choice of a lens. At first one
should buy a 50mm lens and use it for an extended period of
time. Having learned the language of photography, one is pre­pared, and only then, to buy a second lens. The 90mm lens, or
as it was called when focal lengths were measured in centime­ters, the 9cm lens, was the next step. Having bought this lens
and after studying the laws of perspective, one was ready for a
wide angle lens. And finally a 135mm telelens could be conside­red. The first Leicaflex was introduced was only four focal
lengths (35-50-90-135) and this was done on purpose. Much of
what was known in the past, is still valid today. Lenses are like
persons. Only after a long period of companionship, the true
character can be seen and appreciated. A 90mm lens is a more
versatile tool than can be gleaned from the usual catalog des­cription (useful for landscapes, architecture, snapshots,
animals). The 'ninety' is a lens that enables you to really investi­gate the Leica style of photography. If you look at many pictu­res, you will discover that often the image works overloaded as
so many parts of the image ask for attention. A ninety millime­ter lens forces the photographer to a selective choice of sub­ject matter and thus to exploit the space provided by the quite
small negative format to its best. Selective enlargement should
be avoided as much as possible, as any additional magnifica­tion will degrade the optimum image quality. In this sense the
90mm is an excellent teacher

__Artistic reflections

The natural perspective is one where the viewing angle in natu­ral space is identical to the angle of view when looking at the
picture. The eye has a viewing angle that is close that of a fish­eye lens, but in practice the field of vision is much narrower.
Fundamental requirement for the correct perspective demands
that the eye should be positioned at the same location as the
entrance pupil of the lens. There is a simple equation that tells
you that the viewing distance (e) for the correct perspective
should be the focal length of the lens (f) times the negative
enlargement (v). As a formula: e = f times v. If you make a pictu­re with a 50mm lens and wish to look at the negative directly,
your eye should also be 50mm from the negative. But the mini­mum distance of distinct vision is 250mm and so the negative
must be enlarged 5 times. We need a 5x magnifying glass to
see the picture with the correct perspective. Or you should
enlarge the negative 5 times to a print to a size of 13x18cm.
The well known picture format of 10x15cm requires a 4 x enlar­gement and is too small. It implies that you will look at the pic­ture with an extended space perception. You look at the picture
with a wide angle perspective so to speak. When a format of
13x18cm is used and the picture is made with a 50mm lens,
then this 5 times enlargement will provide for a correct and
natural perspective. The picture format of 13x18cm has a dia­gonal with a length of 222mm and that is quite close to the
minimum distance of distinct vision of 250mm. The angle of

view is now about 50 degrees and this corresponds to the
angle of view of a 50mm lens (45 - 47 degrees). But this mini­mum distance is very often quite uncomfortable in many situa­tions. You may not be able to view the whole picture at once
without moving your eyes and the distance of 250mm is quite
short, if you are above 20 years old. Many studies have found
that he most comfortable viewing distance is twice the value of
the minimum distance. If you want to keep the natural perspec­tive, you need a lens with a focal length that is twice the value
of the diagonal of the negative format, thus 2 x 43mm. A focal
length of 86mm, then would be the ideal lens. This somewhat
surprising conclusion can be supported by the following obser­vations. The focal length of 90mm is often described as the
best for portraiture. This is true, but why? Let us make a head
and shoulder portrait at a distance of 2 meter with a 100mm
lens, and enlarge this negative to a print size of 13x18cm. The
formula tells us that we need to look at the picture from a
distance of 5 x 100mm, or 50cm. If we now take the same pic­ture with a 50mm lens at one meter distance, the viewing
distance should be 25cm. But we look at the portrait often at a
distance from 50cm as this is more comfortable. Then we look
at the portrait with a wide angle perspective and the impact of
the image will be different from that taken with the 100mm
lens.

Perspective is independent from the focal length. If we photo­graph a subject from the same position with a 28mm lens and a
300mm lens, the perspective is not changed, only the rate of
magnification. We can verify this, when we enlarge the 28mm
picture ten times. Let us now compare both pictures and we
see that they are both identical in size and perspective (depth
cues). The vertical angle of view of the 28mm lens is 46
degrees and that of the 300mm lens is 4.6 degrees. The vie­wing distance for the enlargement of the negative with the
28mm lens is 28cm (10 times 2,8cm) and for the (not enlarged)
picture with the 300mm lens it is 30cm (1 times 30cm).
If we take pictures with lenses of different focal lengths at diffe­rent distances to keep the size of the main subject at equal
size, the perspective will change of course. The perspective for­mula tells that the perspective impression is only then a natural
one, if the viewing angle of the camera in space is the same as
the viewing angle of the eye at the picture. You can ensure this
when you carefully adjust these three important aspects: enlar­gement factor, viewing distance and focal length. This is true
also when you project slides. The choice of the focal length
should always take into consideration the expected enlarge­ment factor and the normal viewing distance. It cannot be a
coincidence that the 90mm lens was very popular with expe­rienced photographers. And Leica has always offered a wide
selection of 90mm lenses, carefully tuned to different tasks. It
might be a fine exercise to use the 90mm exclusively for one
month and enlarge all pictures to a size of 13x18cm. The vie­wing distance should be about 50cm. Then you really get used
to the correct perspective. A portrait taking with a 90mm has a
'flatter' perspective that is 'flattering' for the sitter.

Chapter 2

Leica R-Lenses

2

__Optical considerations

Within the R-System we have three lenses with a focal length
between 80 and 100mm. Every lens has its special use and
character. We will look at first at the optical properties. Almost
every high speed lens with focal lengths from 35 to 100mm are
derived from either the Sonnar or Biotar basic form. The num­ber of lens elements ranges from 5 to 8. With this amoint of
options the optical designer has an abundance of choices.

Basically the following options exist:

- split a lens in two single lenses
(distribution of refractive powers)

- create a single lens as a compound of two lenses

- change the refractive index of the glass types

- use aspherical surfaces

- split a compound element in two separate elements

- use glass types with anomalous dispersion

The optical designer can use all of these options in any combi­nation to design a lens that delivers optimum performance
according to his set of standards.

The Summilux-R 1:1.4/80mm (from 1980) has the construction
we already know from the Summilux-M 1.4/50 from 1961.
Three single lenses before the aperture and two compound lens
groups behind the aperture. Leitz used two versions of this
design: the last group is constructed as a compound doublet or
as two separate single elements. For high speed lenses the
compound version is better suited, if this group is designed as a
new achromat. It is in fact remarkable how well this design has
served the demands of generations of users. Even from todays
elevated demands we can evaluate the performance as outst­andingly good. With some effort you may detect in the design
the vestiges of a Double-Gauss lens.

A true Double-Gauss design we find in the Apo-Macro-Elmarit-R
1:2.8/100mm. Here we have a six element construction with
two separate thick elements at the rear end. As with the 60mm
macro lens, the computation is designed for universal usage.
When focusing the lens, the whole front lens with six elements
moves and the rear group is stationary. The apochromatic cor­rection is very important when slides or negatives need to be
magnified substantially. The disturbing color fringes are elimi­nated, because of the reduction of the secondary spectrum.
The apochromatic correction is often restricted to the long
focus lenses as the chromatic errors grow proportionally with
the focal length. It was a remarkable decision by Leitz to
employ this correction type in a lens with a focal length of
100mm. The optical qualities have not been surpassed to this
date, although we have some others who are quite close in per­formance. With the 100mm lens, you can take pictures at a
magnification of 1:2 without supplementary tools and still keep
some distance from the subject. The image quality is equally
high at close ups and at infinity. The special construction with
the two thick rear lenses is partly responsible for this behavior.
The use of special glasses with anomalous dispersion helped
the apochromatic correction substantially. The optical design
gas been optimized for the specified task, especially the homo­geneous quality level over the whole distance range. The first
version of the Apo-Macro-Elmarit-R 1:2.8/100mm used a
mount with a double thread, later changed to a single thread, as
the previous mechanism created a less smooth movement.
(from serial number 3469285)

The first Summicron-R 1:2/90mm has been introduced in 1970
and has held the flag for this classical focal length during 30
years. It is a five element design from the Midland optical con­struction department. It has some reminiscence to the Sonnar
design. The system is nose heavy as most elements are in front
of the aperture. The performance is good, but the Summilux-R
is as good and has twice the speed to illuminate the negative
area.

Chapter 2

Leica R-Lenses

3

The Summicron-R 1:2/90mm displays the typical veil of soft
flare over the whole image at full aperture, that is the characte­ristic of almost every high speed lens of the older generation.
The typical use of the 90mm as a portrait lens could serve as
an explanation and defense of this behavior. The soft reproduc­tion of image details and subject outlines created a more
friendly image of most faces of the sitters. But one did the
90mm lens an injustice as it restricted its potential universal
use.

The current Apo-Summicron-R 1:2/90mm ASPH (2002) raised
the level of optical quality substantially. The size is very com­pact and almost equal to that of the current Summilux-R
1:1.4/50mm. Based on size it can be classified as a standard
lens. The optical quality is superb and a revelation. The aspheri­cal surface is grinded by CNC-equipment in a lengthy and ela­borate way. Grinding and finishing takes many hours per ele­ment and is so time consuming because of the many
inspections and checks during the manufacture. If a lens is
manufactured with such accuracy, you need a very careful
assembly. The Leica-typical construction with metal parts of
exact dimensionality is a necessary condition for a high quality

product. This aspherical surface with a large diameter and com­plex shape has to be assembled with utmost care to ensure
that the theoretical capabilities can be practically available.
The optical construction shows a five single elements, and the
first surface of the third lens has the aspherical shape. True
mastery can be seen in this elegant design. Some time ago one
needed seven or eight lens elements and could not get this high
performance. The low number of elements, the choice of glas­ses for transparency and color transmission, the effective type
of coating, all work together to provide the remarkably clear
and crisp rendition. The image quality is very, even at full aper­ture and veiling glare and secondary reflections are absent. If
you take pictures with the sun, directly shining into the front
lens, some aperture reflections can not be avoided.

This layout may be indicative for new designs from Solms. The
classical design with seven or eight elements may be in its final
stage. The current demands have become too high, especially
in relation to the new method of digital capture.

__Three lenses of medium focal length

These three lenses do not only differ in their effect on perspec­tive but also in their performance at full aperture. Everyone of
these lenses could be described as a general purpose lens, with
exception of the special macro facilities of the Apo-Macro­Elmarit. The angles of view are close together with 30, 27 and
25 degrees. In reality the differences are bigger. If we take a
picture of a person and a face in vertical format, the subject
distances are as seen in the table below.

Person 1.76 Meter

6.57 Meter

2.08 Meter

1.86 Meter

7.33 Meter

Summilux-R 80 mm f/1.4
Apo-Summicron-R 90 mm f/2 ASPH.

Face 50 cm

Apo-Macro-Elmarit-R 100 mm f/2.8

7.93 Meter

2.25 Meter

Chapter 2

Leica R-Lenses

4

At these distances the image size of the person is always the same, but the background is clearly different and has its pictorial
effect on the subject. For formatfilling figure photography, the 100mm is a bit uncomfortable as the distance to the person is quite
large and here the 80 or 90 are better suited. The most important selection criterion is the performance wide open. In the next
table I have compared the three lenses in this respect.

Aperture 1,4 Aperture 2,0 Aperture 2,8

Summilux-R 80 mm f/1.4

Medium contrast, some flare.
In the center good resolution,
in the outer zones medium
resolution, some astigmatism
is visible.

Medium contrast, low flare.
In the center very good resolu­tion, in the outer zones good
resolution, some astigmatism
is visible.

High contrast.
In the center very good resolu­tion, in the outer zones good
resolution with some softness,
astigmatism is very faint.

Apo-Summicron-R 90 mm f/2

ASPH.

High contrast, very high edge
sharpness, high resolution
from center to edge.

Very high contrast, very high
edge sharpness, very high
resolution from center to edge.

Apo-Macro-Elmarit-R 100 mm

f/2.8

Very high contrast, high edge
sharpness, very high resolution
from center to edge.

This evaluation is based on very severe conditions. The testsli­des were enlarged to a size 0f 2.40 meter, that is a magnifica­tion of 66 times. Under these conditions, even the minutest
error can be seen, especially as the observer is close to the
screen, where he should not be to be honest! The Summilux-R
shows some characteristics, that are not visible at all at smaller
magnifications. From aperture 2.8 all three may be considered
equal in image quality. The performance of the Summilux is in
absolute terms excellent and should be related to the very high
speed. It is not always the case that a very high speed lens can
be compared favorably to a dedicated macro lens of stunning
performance.The MTF graphs are very informative for the
appreciation of optical performance. These graphs show the
maximum resolution of 40 Lp/mm. That is more than needed
for most picture assignments. The new Digital Back for the
R8/9 has a theoretical resolution of 75 Lp/mm. It is interesting
to know if these lenses meet the requirements.
The Summilux-R reaches at full aperture a value of 100 Lp/mm
in the center of the image and 40 to 50 Lp/mm in the outer
zones. The edge is weak with 16-25 Lp/mm. At aperture 2
these values may be raised by +10 Lp/mm and at 2.8 we have
a center resolution of above 100 Lp/mm and in the outer
zones above 70 Lp/mm. The Apo-Summicron-R ASPH at full
aperure has a value of above 100 Lp/mm over the full image
area, excepting the corners where we still have a stunning 50

Lp/mm. On the optical axis we even see more than 150
Lp/mm. From 2.8 we have a uniform resolution of more than
100 Lp/mm with the edge now at 80 Lp/mm. The Apo-Macro­Elmarit-R has the same values as the 90mm lens at aperture

2.8.

Overall we may declare that all three lenses can exploit the high
resolution of the future digital back and they even have some
reserve capacity.