Second example - Exakta Pocket Guide Reference guide

EXAI(TA  POCKET  GUIDE

                                            'EXAKTA-Tips"                  Title of the Originnl GermanEdition:
               Authorized English translation: Fred.Willy Frerk, London





Printed in Germany. Only authorized English translation. All  rights including that of reproduction in whole or
in part  expressly reserved. Published ryt9  by  Fleering-Verlag GmbH,  Seebrudr am Chiemsee. Printed by
Vilh. Friedr. Mayr,  Buchdruckerei,Miesbach/Obb. This book  is distributed in  the U.S.A. by Exakta Camera
                     Company, 7o5 Bronx River Road, Bronxville, New York,



    P U B L I S H E D   B Y  H E E R I N G - V E R L A G      S E E B R U C K  A M C H I E M S E E   T 9 ' g

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         Foeusing    rrn a acreen   is the  safest  way  to tuccesg

         There is no getting away from  the fact that the old plate camera with  its ground-glass screen
         had  its undeniable merits. When  the photographer  of that era looked  at the ground  glass, he
         had  fuLl control  over the framing,  the  definition,  and the aesthetic value  of  the picture he
        was about  to  take. The  results proved  the soundness of  this method  of photography,  and,
          although  the large plate camera is no longer a favorite  of photographers because of  its  size,
           the ground-glass screen certainly  is  still popular, probably even more so than ever before.
         Long before the invention  of photography    it was known  that an image produced by a lens
          could be viewed on a matted glass plate. The plate camera was the logical development of this
           discovery,  but when  the  plate  holders  replaced the  ground-glass  screen in  the camera, a
          considerable amount  of  time  was  lost  in changing holders  etc./ consequently, photography
            of that time was slow, and people did not show signs of tremendous interest in this medium.  In
          tg36,however,there was a spectacular revival of screen focusing,whenthelhageeKamerawerk  of
         Dresden introduced the "Kine-Exakta",  which, in those days was the only 24x36 mm. (35 mm.)
          miniature camera with a real focusing screen: It was the first single-lens mirror  reflex miniature
         camera in the world and the predecessor of todays "Automatic  EXAKTA  LIGHT-METER   II a".
                 It is true that the Exakta embodied a streanrlined version of the old, well-known  reflex principle
          but   it was unique  in so far as the reflex principle was used in a tiny  miniature  carnera and,
            for the ftrst time, made screen focusing possible in this newly awakened field of photography.
                It-                  possible now  with  the Exakta,  to focus a miniature  image with  the ac&racy  of the            -wa,s
           old plate -camera, but with  incomparable  greater convenience. With  this new single lens reflex
         _camera,the point  of focus, the depth of field and the lighting  conditions can all 6e determined
          before taking a photograph. Even more important,  the pictorial  contenr and composition, those
             vital elements which make a real "picture"  can be studied right up to the moment  of exposure,
        The adoption of the reflex principle by many other camera manufaiturers   is a positive indication
iL,    that the groundglass screen imagg was to play a major role in thefieldof miniaturephotography.

A new  way  of  eeelng  and  photographrng        at  the  rarne  fime
 Prior  to the introduction   of the EXAKTA,   photographers  had to squint through  the usually  tin1, peepholc
 of the viewf rangefinder-: now however,  th.y  h"".  a life-sized,  briliiant   i-agJ   or, ,tr.-f.ourrd-glass  screen
 of  thc EXAKTA.    With  rangefinder  &  twin  lens  reflex  cameras,  rhe  viewfinder          ,h.  Iaking  lens
 are two  units independent  of eadr other,  although  frequently  coupled  ro one another"ndas far as folusirrg
 was concerned.  \rith   the EXAKTA,    the finder and the taking  camera ^re  o,'te unit. The  ,r.ry   ,"-"    l.ni
 whidr  projects the picture  onto the film  also serves for  viewingl  The same t."r  ntrip.oau..,    ah" image on
 the screen and then on the film, no matter what  lens is useJ. Viewing  the s.reen- image  is viewing  the
 future  picture'  since both  are absolutely  identical.  The diagram  below  de-onsrrates   the  optical  rcflex
 principle  on which  the. design  of a single-lens  reflex  ."*.r"-      i, based. The  lens forms  the usual upside-
 down  image  of  the  subject  in  the  fo.al  plane. The  path  of  rays, however,   is interrupted  by  a small
 pivoted  mirror  which  deflects the image of the subject upwards  on to the focusing screen, which  is at the
same distance from  the lens as the focal  plane. The resuiing  screen image appears as an upright,  sharply
 defined picture  in  its natural  colors.  Thi  area covered,  the-relative   brigitrris    a,ra  tt.   a.nnition    will  be
 strictly  idenrical with  those of the picture  actually exposed on the film.
Focusing  with   this  life-sized  image  before  one's eye means photographing    just  what  appears on  the  {
screen and nothing  else. There  is never  the slightesi  differencJ  between the visual  i*";.";;;;;.;;;;\)
on the negative: the single-lens reflex camera is perfectly  free from  parallax...p"r"llli'i]"ai."r.l'ri.5
difference  between  the view  seen in a separate  ,ri.wfind.,   and  that  which  will
the taking  lens' Parallax  is particularly  conspicuos in other  ."-..^,   when used "oruull],^b.',4l;#:;;\ifor  close-ups. There thefinal                    is  quite  different   from   that  seen through  the      -picture
viewfinder.   Parallax-errors   can  arise with  any  cameral  with
the  exception   of  a  single-lens  reflex  EXAKTA.    where  the
same lens  is used  for  both,  taking   the  picture  and  view_
finding.  Even   in  close-ups, photomicrography,   telephoto-
photography,  or on other occasions where  special  l..rre,
used you are never bothered with  parallax.                       "..

www.butkus.usConvertible     earner:a:  a new  prlnelple

To a certain extent the Automatic  Exakta  II a is a photographer's dream come true. Enthusiastic
;["i"gdh.rr        tlu""  always dreamt  of a cameru, i,vhi.h,-although  easy to operate and without
i;    #;,.     ;   t lr,  of u..ess'ories, can be assembled to suit the re(uiret"..ltt    of the task at hand.
In  stort,  a multi-purpose  camera, the_most- imp_ortant-elementJ of which can be converted  to                                            i'tools".                                           This iream  has been realized  in  the "dual'system" i;;        ;  variety  of photog.aphic
Exakta  II a carnera.  tt   tf,"  iu*.   *uy  as one Exakta lens can be, replaced_by- another/ more
suitable for the subject to be taken, the focusing system of the Exaktf can also-be- interchanged
according to the tt."dr  of the moment. The time--honoured reflex finder hood, which necessitates
         "the  grourld-glass image from  above, can be replac-e-dby  a p91t3-prism  viewfinder,
"i"*i"gwhich iermits"viewin!    at eyelev"el and gives an upright,  laierally  correct find.er image..You need
no  longer  compromiie  beiween  a  rigid  cameri-system  and  yo-ur pictorial  ambitions.  The           "IIExakta         u .ur, ie  equipped so that  itllways -to meetl your  parti;r.r,lar d-emands and ensures the
best  results  in  whatever  way  you  prefer     work.   If  you  don't  like  the low  view-point,
unavoidable  with  the finder hboi,  yo^o .ur't use the penta-prism  viewfinder;    if you are mainly
concerned with  taking  children,  animals, people  sitling,  flowers,  rowing  boats,  etc., stick to
the finder hood, since"the waist-level  position gives a more genuine perspective of such subjects
than  the  looking-down   of  the  eye-level  position.  The  important  - thing   is:  the Automatic
Exakta  IIa   is ani  remains a singie-lens  reflex camera with-its   highfy  m-agnified, bright-and
parallax-free  ground-glass screen-image. The finder hood can be used by looking-hasinto   it from
 ubo.r", fro-    iire side"or from  below. ihe  hooded  reflex finder image, tiowerret,     one  little
disadvantage:   it  is upright,  but  laterally  reversed, that  is to say, obiects on the right  in  front
 of the lens-appear on the left on the screen, and vice versa. With  the penta-prism  viewfinder,
 with which the exakta  IIa  is used at eye level, the subject will be upright and laterally_correct
 in  all cases. Before dealing with  a detiiled  description  of the various  applications  of the two
 focusing systems, it would be useful  first to have a look at the various operational components
 of the Exakta  II a.

                                                                                         ,l

Horl a penla.prisrrr viewffndcr  r.orhs
                         Tbe  lelt  ball  of  tbe screen inage (zahen looking tbrough
                             the eyepiece)is reflected lrom the left-band portion of the
                             prism-roof (a) on to  tbe rigbt-band side of  tbe oblique
                            (450) mirror (c), From tbe rightband portion of the prism_
                                roof (b) tbe rigbt-band  ball  ol tbe scr.eenimage is reflected
                          on to tbe left-hand side of the rnirror  (c). On the surlace
                                 of tbe rnirror (c) an upright, laterally  correct image will
                           dppedf.




Cnoss section  thr:ough                                                                   Diagrarn of the prism finder
the  Automatic   EXAKTA    IIa                                   \-
 a)  witb  locasing  hood,

                                            Changing    the  focusing   aystem

                            Tbe  small   catch  on  the  lens  panel   ot'  the  Awtomatic
                         EXAKTA         II  a  should   be  pressed  downroards   and   the
                                 closed   finder   bood   or  penta-prism    attacbment   r.emoaed
                                       frorn   the  catneftt  by   lilting      it  upwards   bodily.   _  Either
                               dttdchment  sbould  be  replaced  carelully  and  exactly  ver_
                                         tically,  without  cdnting.   It  should be inserted  at tbe  correct
                               angle  into   tlte camera,  uhere  a  sligbt  pressure  will   locb  it
                                         in  position  (never use force).
b) witb prism finder

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Do you  know   your   Autornatic    Exakta    IIa?

The EXAKTA  IIa  is a camera which will never      l.6.  Finder hood release button
let you down, but  it  is of the utmost import-     r-7. Slow shutter speeds (r/s-xz  sec.) setting
ance  that    it  should  be handled  strictly   in         knob, also for  setting delayed action
accordance with  the instructions.                          (self-timer)
   r-. Rotaiy  release knob  for camera back           r.8.  Film type indicator
  z.  Camera back lock (operated by knob  r.          r.9.  Film advance control  disc
     above)                                         r9a. Pin-head of back hinge
  3.  Shutter release knob                            2c.. "M"  Flash contact
  3a. Safety lock for shutter release knob            za. Red dot on camera (guide mark  for
  4.  Eyelets for carrying  strap                       changing lenses)
  5.  Frame counter                                                                                            '                 22.  Depth-of-field  scale of the lens
  5a. Frame counter setting knob                   23. Distance  setting  ring  with  feet or metre
  6.  Film advance and shuttertensioning  lever                                                        scale
                         film rewind              pin  for     Release  7.                       knob (1/zs- Lltooo,      24. Diaphragm  setting ring with  aperture           speed                    setting  8.  Shutter                                                      scale    T and B)                                                   z4b. Tensioning  lever for automatic spring  9.  Release catch for focusing units  (finder
    hood or penta-prism)                          diaphragm
                                                    z4c. Release knob  for operating the spring 1 0 .  "F" Flash contact
                                                diaphragm a7-. Finder hood
 7-2. Frame finder cover for magnifier  r3         2 5 . Lens
 L 3 .  Magnifier   (in swung-down  position)         26. Red dot on the lens (guide mark  for                   "
 L 4 .  Operating knob  for  collapsible magnifier        changing lenses)
 L 5 . Back of finder hood (with frame finder       27. Lens bayonet catch
     eyepiece)                                    28.  "X"  Flash contact                                                    :,

                                                            -  :,.    .|   ..                     #

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 29. Empty take-up spool for exposed film
 1.o. Spool chamber for take-up spool or
     empty cartridge
 3T. Film advance sprocket
 3aa.Holding bracket for cartridge
 32. Film guiding  rails
 33. Shutter curtain
 34. Film cutting  knife
 35. Button  for operating 34
 36. Fork for engaging spool
 37. Rewind knob
 38. Centre disc of rewind button 37 (press
     inwards before rewinding)
 39. Chamber for cartridge with unexposed
       film
  4c.. Hinged camera back (detachable)
 4T. Film pressure plate
 42. Tripod bushing
 $.   Penta-prism
 4+. Eyepiece of penta-prism finder

  I

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Ifow  to use  the Automatle   EXAKTA    IIa  wlth  the  ftnden  hood
When the reflex waist level finder hood is inserted into the EXAKTA   II a,
the camera can be used succe_ssfullyin almost every field of photography,
pa11i9u-larlyfor stationary subjects, such as landscapes,architecrurul detail,
 still  life, technical photographs, etc. The highly magnified image on the
ground-glass screen can be examined easi,ly with  both eyes. tf,is  screen
is  actually  a plano-convex lens, acting as a powerful  magnifier,  the
lower side of which  is finely matted. For criticilly  sharp foiusing  this
magnifyilg-  screen is  truly  an  asset; horvever,  tb  ensr.rr. the  hi-ghest
possible definition a second magnifier is built into the camera in the front
wall  of the finder hood and can be folded up inro the viewing  position.
 It  is of rectangular shape and allows almosr the whole image Tieta to be
viewed, providing  a  high  (6 *)  magnification  of  the  reflected image.
Satisfactory horizontal pictures can b-e obtained by either of the follow-
i.g  focusing methods:
Use the full aperture,of the lens (see pages rg-25)-Thenand focus to the highest
possible definition  by  using  the  magnifier.        return  the  folding
magnifier to its rest position and watch the subject on the focusing screen
until the shutter is released,holding the camera at either chest or Jhoulder
level. The diaphragm should be re-set to the aperture required, either
shortly before the exposure is made (with lenses with pre-sel diaphragm)
or simply by releasing the shutter (with lenses with  automatiC spring-
diaphragffi, (see page 4).
The other way  is to hold the camera as near to the eye as possible and
to watch the focusing screen by  using  the magnifier.  Naiurally,  pre-
selecting the aperture should precede focusing at  full  aperture with-the
aid of the magnifier.

                            7 0

Both these methods can similarly be employed for vertical pictures. In this
case the picture is taken "around the corner", so to speak, and this is an
ic{eal method for candid shots. By looking  straight in  front  of you, the
actual taking direction is "camouflaged" while the subject is snappeclat
an angle to the right or left. You may also hide behind a wall or a tree
rvith only the camera sticking out.





as walls or hedgerows. In this case the EXAKTA   II a is sin-rply held atrovc
orlc's hcad and the screell irnage examined frorn below.





corrcctly. For close-ups at distances of less than 9 feet, the frame finder
shoulc{ not be use'c{on accoullt of parallax. Spcciacle wearers using the
re'fle'xfincler hood (with thc rnagnifier) shoulcl-focus the subject witlr the
slrcctaclcsthev normallv wL.ar for reading.

                                                             7_7

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Hov'  to use  the  Autornatie   EXAKTA    IIa
wlth  the  pnisrn-viewftnder
Equipped with the penta-prism, the EXAKTA  II a becomes a "rapicl-action
camera". When the subject is moving rapidly, as in sports events or even
in daily  life (cars, horses, aeroplanes,etc.), the enormous advantages of
the prism-viewfinder will soon be obvious.  I t ensures a direct eye-level
view of the subject, the lines-of-sight of both the eye and the camera are
always identical and the image in the finder moves in the same direction
as the subject in front of the lens. In addition -  the image is upright and
laterally correct. All these advantages apply no matter whether horizontal
or vertical pictures are taken. A racing car travelling at tremendous speed
can easily be sighted even at a considerable distance and kept within  the
image field up to the last moment. Slowly "swinging"  the camera, one
follows the car and releasesthe shutter shortly before it reachesthe point
on which the lens has been focused beforehand. When using lenses with
pre-set diaphragffis, the stop required should be set beforehand; with
lenses with  semi-automatic or  automatic diaphragm  setting, stopping
down to the pre-selected stop is done automatically.
When photographing subjects which call for the fastest possible shutter
speed, such as those which have to be taken  at  right  angles to  their
direction of motion (ski-jumping, car or motorcycle races), it may happen
that even the shortest shutter speed of 1/rooosecond is not fast enough to
 freeze motion. These are cases when "swinging  the camera" is indicated.
Get the fast-moving subject in the viewfinder while  it is still at a distance
and keep  it  constantly  in  the centre of  the viewfinder by moving  the
camera slowly but  steadily along with  the moving  subiect, as described
above.

                              7.2

Using the prism-finder and making the Automatic EXAKTA  II a an'action'
camera, however, does not mean that  the prism-finder should be used
only  for action shots at the fastest shutter speed. Whenever  it appears
more suitable to use the EXAKTA   II a at eye level and to focus critically
on the laterally correct reflected image,  it can and should be done. The
dual-focusing system of the EXAKTA   II a has been introduced with  the
definite purpose of  replacing the categorical "you  must"  by  the more
tolerant "you can".  It  is quite possible that certain subjects will  give a
better picture when taken at eye level, because they are habitually seen
from  the eye-level position (persons, architectural details, technical sub-
jects, etc.). Sometimes a subject cannot be viewed properly by looking
from above into  the finder hood;  well, then, use the prism-viewfinder.
The  correct application  of  the  two  different  focusing systems soon
becomes a habit -  you will select the most suitable method almost auto-
matically. Both  horizontal and  vertical  pictures can be taken without
difficulty.  Horizontal  shots can also be made with  the camera upside
down which permits the smooth back of the camera to be pressed against
the forehead for protection against camera shake.
Furthermore, there is eyepiece which can be slippecl on the eyepiece of the
prism-viewfinder, preventing stray light from both sides entering the eye-
piece and making  it possible to press the camera firmly against the face.
Peoplewith defective eyesight can have a corrective glass fordistant views
fitted to the eyepiece.
The stanclard grounc{-glass eyepiece can be replaced by  the split-image
rangefinder glass. It pennits precision focusing by means of  its built-in
split-image rangefinclerand can be usecl with lenses of  all focal lengths
For focusing a rvic{eaperture (not under fr 5.6) should be used as usual.

                                            L 3

www.butkus.usPr.eedng  the  r.elcaee knob
starts a chain of interesting events inside the Automatic EXAKTA  II a. You should make a
careful study of these operations before loading the camera, preferably with the camera open
and the lens removed.
When the release knob is depressedthe mirror  flips upwards and seals off the ground-glass
screen,so that the beam of,light lrom the lens can faf on the film in the film ga"tewhen"the
focal plane opens-'The focal plane shutter, consisting of two blinds oI rubberizeidcloth, has a
slit between the blinds, whidr  is either narrow or *ide  accordinq to the sDeedto whidr the
shutter is set. The slit travels along the film from left to right and"exposeseachportion of film
for exactly that exposure time to-whidr  the shutter is se-t.At the same insta'nce the frame
counter advancesby_one stroke. Depressing the releaseknob once again has no effect at all,
since the whole mechanism is no longer tinsioned. When the film irarrsport lever is turned
until   it stops, the shutter will bo teniioned once again, the film  will  bl advanced and the
mirror will return to its vlewing position, that is to say, the screen image will again become
visible. Unintentional double expoiures are impossible, is the fflm can be"advancel only when
                              the shutter has been released.Even when the transpoit lever
                              has not been turned as far as  it  will  go but has been left
                                      at an intermediate position, the shutter  will  be locked. For
                                   intentional double exposures, see pag e 47.
                          Hozo to operate the shutter
                           The use of the various shutter speeds will be described later.
                              Small setting knob: Shutter speeds from  l/es to 1/rooosecond                                            ttB"                                                                    'tTt'                                                                                                  ttTtt                             and                                     and                                                    are set by  this knob.                                                                                                         is for time ex-
                              posures of more than rz seconds duration. The small setting
                             knob should be lifted  slightly  before or after tensioning-knobthE
                                   shutter and turned  in  the diiection  of the arrow. The

                                           1.4

The required shutter speed (in black-figures) coincides with  the red dot in the centre. Then let
the knob spring back. For the actual exposure release the body release knob of the camera asgently as possible.
Self-tintcr cxpostffes (delayed'knob).  action release 13 seconds after
depressing the release
a) ExptssllresbetzueenIl; sec. nnd 6 seconds (red figttres)
Proceed as before, but set the large setting knob so that the recl
mark coincides with the red figttris.
b) Ex1toutresbetueen  t lz; and 1/tooosecond
Set the small.setting knob to the actual exposure time required,
proceed with large setting knob as before, but turn  it so that the
centre mark coincides with  any red figure.

                                           L 5

direction of the arrow so that the last dividing stroke before "L"
points towards the small black triangle.
The EXAKTA  II a is ready for thc first shot!
The EXAKTA   II a is designed so that the take-up spool usually
supplied can be replaced by an empty film cartridge of normal
commercial type. The film neecl not be rewound  in  this casc,
but can be removed from the camera together with the take-up
cartridge. Since the film  is in a light-tight  container  it  is not
necessary to expose all 36 frames, it can be relnoved after any
number of exposures (see page ag). It  will  then be necessary,
however, to trim  the beginning  of the remaining  film and to
 attach   it  to  the  centre  spool  of  another  take-up  cartridge.  With   respect  to  trimming,
 the necessary curved cut should begin between the ninth  and tenth hole of  the lower  per-
 forations. When  re-inserting the closed cartridge the prongs of the film transport lever should
engage the small bar in the cartridge, anc{ the cmulsion side of the film must face the film gate.
TIte snrcoth umning  of the filtn
and its corrcct advance can be controlled by watching the film  control disk or rotodial  in  th:
circular holc on the outer rim  of the large shutter speed setting knob:   it should rotate when
 the film  is advanced. The film  type indicator around the base of the large setting knob  (not
 to bc confused with  the shutter speed setting ring) should be set to the type of film with which
 the camera is loaded. The ring underneath the large knob should be turned in an anti-clockwise
 direction until the type of film  in question coincides with  the small triangle. The figures denote
 the speeds of the various black-and-white  films  (e. g. z3 ASA, roo ASA  etc.). For color films
 Ietters are provided as follows:  black "C"  for  daylight  color reversal film  (as Kodachrome),
 red "C"  for color reversal film  for  artificial  light, black "NC"  for daylight  color negative film
 (asta color negative), red "NC"  for color negative film for  artificial  light.

                                       77

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Unloadlng    the  ,lutornatle   EXAKTA    lla
Wlrcn 36 <tr 20 cxposurcshavc bccn made it is usually possible
 to adc{ two n'rorc cxposurcs, be'fore the film aclvancclever of
thc EXAKTA  II a bcct-uncsirnmovable. Thc carncra should thcn
be unloadcd.
Wltcn rrsirrgtltc takc-tt2ts1tool
irnc{thc filrn transport lcver canllot bc rnovec{to its rcst posi-
tion bccause the cnd  of  thc  filrn has becn rcached, the
rcwinc{ catch or  pin  G5)  shoulcl be clepresseci.The  film
arrlvarttcclcve'r carl then bc rcturncd to its initial position.
To rcwind thc fihn, dcprcss the ccntrc clisk of thc rewind knob.
Thcn holc{ thc carncrAas shown in thc illustration and rewind
thc fihn by turning thc rcrvinc-lknob slowly ancl cvcnly in a
cloc-kwisedircction whilst keeping the rcwind pin cleprcssed
ar[l the tirtrc. Rcwincling can bc controllccl casily by observing
the control clisk on the outcr rim  of the spindle of the film
trarlsport levcr (the onc with the big scrcw nick). As soon as
this spincllc conlcs to a standstill the film  is rcwound. Whcn
the rcwinc{ pin is relcasedit will rcturn to thc initial position.
Thc canrcrA cArl now bc opencd ancl thc cartridgc with  the
cxp'tosediilm rcmovcd by prulling the rcwirrd knob out as far
ns it will go. Bcforc ckrsing thc carncrAback the rcwind knob
shtlr.rlclbc ptllshcclback in its initial position.
WItcn ttsirtg a tnke-u1tcartridge
rcwinciirrgis unnccessary.When the cnd of the film is reachcd,
rnaking the film transport lever immovable, unscrcw the knob

                        t 8

of thc film cutting knife (lS) by turning  it  in an anti-clock-
wise direction and pulling  it out from the camera. This wili
cause the knife at the end of the rod to cut right through the
film. Now push back the knife and tighten the screw. In ordcr
to wind thc film right into the cartridge turn the film trans-
prlrt lc'vcr anc{rclcasc the shuttcr twice. Now opcn thc cantcra
and remove the exposed film.


The engravings   ar<rund  the EXAKTA   lenses

inc-licatethc narnc of  the manufacturer, the name ancl thc
optical clata of the lens in use, and also include various scales.
Thcse cngravings are of the greatest importance, since the
clata given provide all thc knorvledge necessaryfor using thc
lens just for thc purposc for which it is clesignecl.

There is, f or instnncc,f 12.58rttnr.Wltnt dctasthis ntenn?
The  light  rays rcflected from  the subject are "collcctetl"  by  thc camcra lens (consisting of
various high-quality  lens components) and maclc to convcrgc to give a picture of the subject.
The light rays coming from a distant point enter the lens in straight lincs almost parallcl to thc
optical axis and are brought  to a focus behind the lens, in the focal point. The distancc bctwcen
the lcns (approximately from the diaphragm plane) to the focal point  is called the focal length
and denoted as  f  ('=focus) so-and-so, usually cxpressed in millimetres. So  f -58 mm. means
a focal length  of 58 mm. Subjects which  arc ncarer to the camera are not depicted sharply
by the lens in the actual focal plane, however, but behind  it. To compensatc for this difference
thc lerrs must be "focused' on a shorter distance, that  is to sav, the lens must bc movcd

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forward  slightly  in order to place the sharp picture correctly  in the film plane of the EXAKTA
in accordance with  the increased lens-image  distance. This  is done by  turning  the distance
setting  ring;  the  result  of  this  operation  can be watched on the ground-glass  screen of  the
EXAKTA   II a and read off from  the distance scale in feet or merres.
In any lens, the amount  of  light  passing through  is limited  by the metal  circle of the mount.
A room  with  a large window   will  be  brighter  than a room  of the same size with  a small
window.   It  is the same with  the camera. Lenses are classified as high-speed, medium-speed,
or low-speed, and this highly  important  factor  is denoted by the numerical  ratio between the
diame'ter of the largest aperture and the focal length  (d:f).  Thus a lehs of 50mm.  focal length
and a maximum  aperture of 18 mm. has a speed of  rB :5o,  or as  it  is usually expressed
t : 2 . 8  o r  f / 2 . 8 .
However,  the high-speed EXAKTA  lenses are not  always used  at  this maximum  aperture
although   it  is ektremely useful for focusing. The EXAKTA  lenses have diaphragm  setting rings
which  permit  the speed of  the lens  to be reduced, that  is  to  say, to  give  the  built-in   iris
diaphragm  a smaller  aperture. There  is a scale on the diaphragm  setting  ring  showing  the
various  f/numbers. The smaller the f/number  the larger  is the aperture and consequently the
quantiqy  of light passed by the lens, the larger the f/number  the smaller  will  be the aperture.
An  I/4lens  passes half the light passed by an flz.8  lens. Hence, the smaller the f/number  the
shorter  is the exposure needed, whatever  the  lighting  conditions.
The  calibration  on  the diaphragm  setting  ring  are arranged  so that  in  passing from  one
f/number  to the next  the amount  of  light  passed by  the lens  is halved  or doubled.  If,  for
instance, the correct exposure time  at  fl8  is 1/so second,  it  will  be 1/roo second at  f./5.6 but
1/zr second at  f./tt.  The diaphragm,  however,  is not intended  only  to exclude or admit  hght
to a varying  extent as required, but  is primarily  used to increase the depth  of  field and to
improve  to a certain extent the overall  efficiency  of the ,lens.
Befo_redescribing the most important  uses of the diaphragm  the latest development  in improv-
ing lenses should be mentioned:  the coating.  All  modern lenses and, of course, all EXAKTA

lenses are coated, that  is_to say,  all lens surfices have an anti-reflection  layer which  largely'u
 eliminates the surface reflections  in a compound  lens. These reflecions,  whiA   ut"  u.t.tuiiy
 scattering of the  light  at the glass-to-air  surfaces, increase with  the number  of surfaces, and
 degrade the image co_ntrast.By coati_ng.the surfaces the loss of light and the decrease in contrast
 have been eliminated  to a very  l_righ degree; after coating, lensis have proved  to have gained
         and to give greater                                       -brillilnce  ind  contrast. Coiied  lenses cun b" recognized 5y the it] ?p,""4
 bluish-red  tinge of the front  lens.

                         diophrogm


                     opticol
                      o x t s




E X A K T A  P H O T O G N A P I I Y
by Jacob Deschin

A  worhing  rnanual  lor  the EXAKTA    and. EXA   cd,lterds whidt  thoroughly   explores  the  operational
details and picture-taking  potentidls  of botb cdmerds.
ro"  x7",   r92 pp,, z5o pbotos         fi .+.gS
Aoailable   dt yoar  dealer  or EXAKTA   PUBLICA.T/ONS,    Box  97,  Bronx'ztille, New  York

                                                        27.

www.butkus.us
The effect  of stopping'down   a lens

Although modern lenses of large aperture are highly corrected their dep_thof field is compara'
liv"ly  s"matl.Furthermore,thef trinsmit much-morL light than is usually neededfor modern
films' and even if the deiiniti6r, .ur, be consideredas very good at full aperture, it  will be
improved when the lens is stoppeddown. The "resolving power" or "resolufion" is the ability
of a lens to separatethe finesi details of the subject. This resolving power is at its maximum
at one particular medium stop for each type of lens, usually fl8 (with lensesup to f.l-z'8).and
f/S.e (wittr higher speedlenserl. The highest speedof a lens or its largest-apertureis therefore,
uJuaily only rised ut der poor iighting conditions or for rapid-action work, e. g, for car-racing,
when the highest shutter speedis needed.
 In theory a photographic lens can only provide a critically sharp image of the pllne on which
 it  is foclsed^.In ictual practice, howerr"t, a lens does not only defin-esharply objects-at the
accuratelyfocused distaice but will also produce a_sharp image of-objects a certain distance
 in front tf  and behind the actual distance focused. This "zone of sharp definition", better
known as "the depth of field", is comparatively narrow at  full aperture (tlz or f/2.8) but
becomesgreater ttie more the lens is stopped down. With the EXAKTA lenses we need not
go into a- detailed explanation of this faii; we look into the finder hood and focus at full
 ip.rtur.  on an obl"ciat  a distance of, say, 16 feet. The 9l?jectin que_stionwill be perfectly
 ,irurp, but in froni of it and behind it  all other objects-will be more or less unsharp. With the
 starriard lens of 50 or 58 mm. focal length many objects near the one on which we have
 focused wil,l still ie  shu-tp,but with a long focuJ lens the zone of sharp definition will be
 smaller the longer the focat length of the lens; converqely,_withwide-a181e-lelses,the 4.p,4
 of ii.ta wil  be"greater the shoiter the focal length. The depth of field will also be reduced
 when the taking distance is reduced.

                                                   2 2

{ow,  when we reduce the aperture of our standard lens we can observe quite clearly how the
 depth of  field grows the more we decrease the aperture, and how the zoni  of sharp-definition
becomes much greater beyond the distance focused on (5 ft) than in front  of  it. Aciually   t/r of
 the depth of field lies in front of the plane focused on and 2/g behind  it.
 All lenses of the EXAKTA  IIa have a depth-of-field scale cngraved on their mounts. This scale
shows thc zonc of sharp definition  at various aperture settings and distances. ln the centre the
 red mark  is sct to the distance focused on (16 ft). When now the aperturc setting to be used is
located among thc f/numbers to the lelt and right  of the red distanic setting maif,  the distance
values on the distance sctting scale opposite the selected f/numbers represent the near and far
 limits  of the depth-of-field zone. For instance: Focus on r6  ft. stop f/8; sharp definition  from
ro  ft. to 5o ft. (See illustration  alongside).
Examining  the ground-glass screen while  decreasing the aperturc  will become more  difficult
bccausc a small apcrturc docs not transmit as much light as a large onc. Aftcr somc experience
this darkcning of thc focusing screcn can becomc quite uscful fordcterminingthc  cxposure timc.
Thc full aperture of a lens gives the most brilliant image of the subjcct in front of the lens, but
for the actual exposurc thc diaphragm must be closed to the stop requircd. In ordcr to save time
the lenses of the Automatic EXAKTA   II a have either a
fully autonlatic diaphragnr, a semi-automatic diaphragnr
or,  at  least, a manually  operated ring  which can be
turned  to  the pre-set stop just  before the exposure,
without having to consult a scale.With the latter device
the aperture necessary for  the exposure should be set
before focusing and the focusing done at  full aperture.
With  the semi-automatic diaphragm  it  is necessary to
tension the mechanism beforehand, whilst the automatic
diaphragrn springs back automatically to the pre-selectcr{
stop when the shutter releaseknob is depressed.

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