Light meters
Weston Universal Exposure Meter Model 617 - Type 2 User manual
User manual for Weston Universal Exposure Meter Model 617 - Type 2. 27 pages in English. Read the original PDF, download or print a copy without registration.
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- Weston
- Model / document
- Weston Universal Exposure Meter Model 617 - Type 2
- Document type
- User manual
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- English
- Pages
- 27
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- 3.5 MB
- Category
- Light meters
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Page 3 · Read text
F{ow to Use the
WESTON UNIVERSAL
EXPOSURE METER
CHAPTER I
INSTRUCTIONS FOR THE
AMATEUR PHOTOGRAPHER
CHAPTER II
INSTRUCTIONS FOR THE
ADVANCED PHOTOGRAPHER
. MISCELLANEOUS
INFORMATION
APPENDIX
Copyright, 1933
Weston Electrical Instrument Corp.View original page 3Page 4 · Read text
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THE CORRECT WAY TO HOLD THE
VESTON EXPOSURE METER
CAUTION
When aiming the Exposure Meter at trhc
scene to be photographed, do not allow
your fingets to drop behind the rneter in
such a menner as to partially cut off the
light from the photoelectric cell which is
beneath the glass q'indow.
Direct sunlight does not harm the photo
cell but if it is allowed to enter the cell
opening while making a me:lsurement it
will cause an erroneous rcading of the
scene's brightness.
,f Keep the glass window over the cell
oPening clean.
.,1\* During dry cold weather the glass on
the instrument is likely to become electri'
fied by contact with the hands or clothing.
This attracts the pointer and gives erro'
neous readings, but the charge on the
glass can be easily eliminated by breathing
Direct the meter upon lt.
at the center of
the scene. If the
scene includes too much sky
light, turn the Iine of sight
(along the edge marked by arrow) slightly
downward.
I2l l3lView original page 4Page 5 · Read text
DESCRIPTION CHAPTER I
OF EXPOSURE METER INSTRUCTIONS FOR THE AMATEUR PHOTOGRAPHER
The Weston Model 617 Exposure Meter Let us assume that you are photograph'
functions by instantaneously indicating the ing an average scene and are using a 6irn
Setaccurate light value of the scene or object which is designated with a speed of t2. arrow so that the white dial, middle, orbeing photographed, with neans for imme' the as dial bottom black points the on to 12diately translating that inf ormation into thou'n at D in Fig. 1. When turning the
proper combinations of aperture and shutter white dial, slightly lift it with the thumb
speed. nail under the arrow. This setting sands
until a film of diferent speed is used-
If you look at the face of the meter you thereaf[er only the top dial requires setting
wili note that at the right is an exposure Then: l. Aim and Read the Meter.dial and at the left is a light value indi,
cator. The use of the dial, as explained Hold the meter at eye level, poinling it at the object or scene to be photographedla[er, translates the brightness of the scene as sho',vn on page 2. Do not include sun,
into proper exposure values in accordance or more sky than absolutely necessary if
with the various plate or film speeds and out,of,doors, or light or windows if indoors.
thethe type of scene being photographed. On That is, point the meter directly to object you are interested in phocographrng.the back of the meter you will notice a Note the number to which the light in'
well, under glass. At the bottom of this dicator points. Let us assume that ic points
well is a V/eston *PHOTRONIC photo, to 200, as shown at E in Fig. 2. (If the
electric cell or "electric eye." The light indicator shows a deflection of less than 100 then use the push butcon as describedfrom the object or scene falls on this on page 10.)
dry plate electric eye and is instantiy con, 2. Set Dial and Read Aperture andverted into electrical energy which directly Shutter Speed.
operates the light value indtcator. Assuming the scene is "average " or
TPHOTRONIC-A copyriglted nanre *sed to "normal", turn the top black dial around designote the pltotoclectric cclls ond deaiccs until the "Normal" B arrow points to 200
monufacturcd crclusiaels- bt thc Wesion Elec' on the bottom black dial as shown at F tricol Instrtmcnt CorPoration. and G in Fig. 3.
t?t IrlView original page 5Page 6 · Read text
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The correct combinations of shutter For example, if the meter indicates f/?
speed and apcrture are then automatically and the camera is marked in the series
shown on the too black dial and white dial. f /r.6, f /6.3, f /8 etc., set the diaphragm
lf l/2, sec. is seiected as the desired shutter index to the nearest number f/6.3 or you
speed, then as shown directly above at H, may approximate more closely by setting
siop f /Ll should be used. When taking stills the diaphragm index between I/6.3 and f/8.
you have the option of using several com' NOTE:-The majority of high' gradebinations, and any one selected will give cameras are marked with the f/ system ingood negatives. To illustrate, if. you are which the exnosure time required varies as
taking an action picture, and must have a the square of the f/number. There are
sharp definition, then a higher shutter speed also many cameras marked with U.S.
mav be required. sav l/100 sec. which numbers (Uniform System) wherein the
shows that stop its.o'should be used. If exposure time required varies directly as
the scene is devoid of action and a smaller the U.S. number. To take care of allstop is desired to obtain depth of focus, types of cameras the top black dial of the
ur" for instance l/IO sec. with stop f/L8 or Exposure Meter is calibrated in both
anv of the combinations shown on the dial. systems.
In' general, the smaller the lens opening, Remember that the SHUTTER SPEBDS
the sharper the picture. on your camera cannot be changed from
It will be observed that there are many their marked values by setting the index between nurnbers but the APERTUREmore shutter speeds and aperture numbers INDEX may be placed anywhere betweenon the calculator than are found on any nurnbers'one make of camera, but the calculator was t3 v*Ku+.' ,ts
so designed to include practically all num' HOW TO SET THE METER FOR At\rybers found on the standard types of do' SPEED OF FILM
mestic and foreign cameras. Various makes and kinds of film difrer
In using the calculator you should select in speed and vary with the kind of illumina, necessary to know thethe shutter speeds found on your camera tion. It is therefore th_e_ film to be used, i"hich is givenand disregard others. Then if the corre, !p"ej .ofsponding aperture number is not marked in Table II on page 40 for chose most
on your camera use the nearest value to commonly used.
the one indicated by the calculator, or better To set the meter for the 6lm being used,
still, set the diaphragm opening propor' turn the white dial arrow to its soeed value
tionately between the marked values on indicated on the bottom black diaj-shghtly -the camera in accordance with the relative lift the whire dial wirh rhe thurnb nail
spacing on the calculator. under the arrow and turn to the film speed
t6l I7lView original page 6Page 8 · Read text
www.butkus.us to be used. This setting then remains un, B-Normal Scenes-These include average changed until a film of different speed is used. scenes where the area of high lights
and shadows is approrimately equal WHEN TO USE PUSH BUTTON and include such views :ut open streets,TO CHANGE INSTRUMENT RANGE ordinary landscapes, portraits in the sun
The light value indicator has two ranges. or shade, beach and river scener and When the button on top of the meter is
not preesed the scale should be read di, all normal obiects.
rectly, viz., from 0 to 1000. When the
pointer indications are less than 100 depress G-Dark Scenes with Strong Qe66ae1- the push button on top of the meter. The These include scene. having dark pointer will then move ten times farther up
such the scale, making it much easier to read. I shadow areas and strong contrasts
When the button is depressed, the pointer 'l as are found in narrow streets among
indications or readings must be divided by high buildings, raviner and scenes un, ten because the scale then becomes 0 to der trees with heavy foliage, etc. In 100 instead of 0 to 1000. ' these scenes more than normal expo,
sure is required. PROPER CLASSIEICATION
OF SCENES WILL IMPROVE . Exposure values for scenes falling in clasc PHOTOGRAPHIC RESULTS A or C are determined exactly as described
Uniformly good results will not be ob, for average scenes except that the A or Ctained if all scenes are considered as aver, scene arrow is used instead of the Normalage. The Exposure Meter dial divides the
various types of scenes into three general B arrow.
groups as shown, namely, A, B and C.
See Fig. 4. The arrows marked "DARKER OB,
A-Distant Scenes with Weak Qenrasl- JECTS WILL BE UNDEREXPOSED'' These include very distant iandscapes and "BRIGHTER OBJECTS WILL BE. and sea views which, because of their
distance and generally small shadow OVEREXPOSED" are used when fitting ' areas, require less exposure than aver, the brightness range of the scene to the
age scenes. film latitude as discussed in Chapter II.
[10] [ 1t ]View original page 8Page 10 · Read text
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Chapter I of this booklet covers the Expressed mathematically, the exposure describes the meter andoperation of , the on the emulsion is proportional to+ exposure correct determiningmethod of
by measuring the average brightness of the where B : brightness of the object, t is s'lfitEcene to be photographed. the shutter speed, and f is the stop
number. The instrument is calibrated in The purpose of this chapter is to acquaint ft. i t..those more advanced in the art of photog' brightness units, candles per sq.
raphy with additional methods of obtaining When light falls upon . ,"rrr;tij1r#i: brightness theexposure by means of which " physical place change takes as is well the film I scene can be fitted torange in the known, depends -and the change risultingrange or latitude so as to obtain any desired upon the intensity and color of theaveiage density in the negative, and special illumination on the film; upon the time itlighting effects. acts; and also upon the sensitivity of the To obtain these special effects it may be emulsion. When the plate is developed, the
helpful to refer briefly to the theory of ex, sensitized silver salts which were acted upon
posure and how the meter functions with by light are reduced to metallic silver, lndrelation to the well,known H Et D expo, the amount of reduction is a function of the
sure curve. exposure and the time of development.
scien, It has been shown *'mathematicallv that This effect was made the subject of tific investigation by Hurter Et Drifield.the brightness of an object is the true They found that, for a given development,criterion of exposure, and not the intensiry if values of density are plotted againstor quality of light falling upon the object, logarithms of the exposures, a character,as is frequently believed. istic curve results known as the H ei D
Exposure is the product of the illumina, curve. A characteristic curve typical of
tion available on the photographic film and average commercial films is illustrated on
the time it acts. From this action of ex, pages 24 and Zt. The lower end which
posure upon the photographic emulsion it deviates from the straight line at the pointcan be shown that there is a direct relation d is the region of underexposure, the
between the brightness of the object to be straight portion is the region of correct ex.
photographed and the resulting effect in posure and the upper portion which extends
the final negative. beyond the straight line at the point b is
the region of overexposure. This does notrf ournal Motion Picturc of the Society of En- mean, however, that the under and over giteers, PHOTRONIC Photogrophic " Erfosurc Meters," Vol. 20, pagc 96, 7933. exposure regions are not frequently useful
[14] [ 1r ]View original page 10Page 11 · Read text
have an equally great scene exposure range,and often used. Darkest obiects and the that is, choice of exposure. In the ex, brightest high_ lights of any siene may well ample given above for the relatively narrow extend into the lower and upper regions, respectively. brightness range of 32 to 1, if this range
is placed at the low end of the film range,
Referring to the characteristic curve it then any exposure less than the correctwill be noted that the range of the 6lm value will result in underexposure' of thewher e correct exposure may be obtained, lower tones, but the exposure can be in,
between the poinis d, and b', represents an creased 4 to 1 and still give a good nega,
exposure ratio of about L28 to 1. This tive. If the scene range is set to give a
ratio varies for different types of 6lms and medium density in the film range, i.e., at
with the time of development, but for the ? the center of the H €t D curve, then anpu-rposes of the S/eston meter design, this error in estimating exposure exceeding a
average value for the fiim range was ratio of 2 to 1 will result in either underl1f.? or overexposure. In this case the scene I A.ty given scene to be photographed exposure range is 2 instead of. 4. It has
generalconsists in general of objecti of Jrferent been found by experience that in
can,dcgrees of brightness and color, varying even photographers of long experience -from relatively dark to relativeiy 1ight,'and not estimate as closely as this. For wider
the problem in exposure is to properly fit brightness ranges, the scene exposure range
expo,the range in light values in the scene so diminishes and correct estimates of
isthat they will lie within the straight line sure become increasingly difficult. It -portion of the characteristic curve. If, for obvious, therefore, that some means forexample, in a given scene the ratio of the correlating brightness and liim ranges ir
brightness of the brightest object ro thar of necessary for the best work,'Westonand it is forthe darkest object in which detail is desired this purpose that the Universal
is say 32, then the brightness range will be Exposure Meter was developed.
only one,fourth of the 61m range, and the Referring once again to the characteristic
sccne will bc correctly exposed if it is placcd curve on pages 24 and 2t you will note
anywhere on the 128 to I fiim range. On below the characteristic curve that a sen,
the other hand, if the brightness range is sitometer strip representing a developed
approximately 128 to 1 then you have no 6lm appears in which the successive den,
choice arrd the exact exDosure must be sities are the result of exposure propor,
known. tional to the figures given for the curve.
This strip serves to illustrate that no per, Modern films have a great iatitude or ceptrble density of the negative results until6lm range, but it does not follow that they
[ [16] 17 ]View original page 11Page 12 · Read text
the point d is nearly lssshgd-ghat from www.butkus.us
point d to point b the density increases
uniformly and that beyond b the density no
longer increases proportionally. This illus,
trates the under, correct, and overexposure
regions, respectively. You will also note
that at the enda of the correct exposure
region of uniformly increasing film densi,
ties, are two arrows marked DARKER
OBJECTS WILL BE UNDEREXPOSED
and BRIGHTER OBJECTS WILL BE
OVEREXPOSED. These correspond to
the two positions so worded on the calcu,
lator dial. This dial is so designed rhat
these positions indicate the brightness limits,
which for the indicated shutter speed and
aperture settings, will cover the correct 61m
exposure range just as shown on the expo,
sure strip.
5 These arrows provide the means for Fig.
properly setting ttre brightness range of the
scene to the 6lm range to produce the best
exposure.
wall having a brightness of 6.i candles per The position designated "Darker Objects sq. ft. If the top dial in Fig. i is set so
\ilill be Underexposed" is so located on the that the darker object arrow points to 6.1,
dial that when set ro any light value an then, using a film with a speed of IZ (see
object having that brightness, when used Table II, page 40), if the camera is ser to with the indicated values of stop and shutter one of the exposures inrlicated s a y speed, wjll result in an exposure on the l/2, sec. at f /8, that shadow will have the plate or film corresponding to the lower end'of the straight line portion of the charac, minimum correct density corresponding to the point d on the film strip. In a similar teristic curve. For example, assume an ob, manner, when the arrorv "Brighter Objects ject of any brightness, say a shadow on a will be Overexposed" is set to any light
[18] [le]View original page 12Page 13 · Read text
value and the indicated stoo and shutter In any scene to be photographed, if you
speeds are used, then objecis having that can rneasure the brightness of the darkesc
light value will result in an exposure cor, and brightest objects in whrch detail is de,
responding to the upper end of the straight sired, it is oniy necessary to set the top
portion of the characteristic curve-for ex, black exposure dial so as to include these
ample, assume some object o[ any bright, extrernes of scene light values on thc bot,
ness, say a white door on a house, having torn black dial anywhere between the'Dark,
a brightness of 800 candles per sq. ft. If eet and Brightest Object arrows on the top
the brightest object arrow is set to 800 and dial and a correct exposure will result, if
the camera set to one of the exposures in, the indicated shutter speed and aperture
dicated say l/21 sec. at f/8 as shown at are used.
V and W in Fig. t then the density of the To further illustrate, let us transfer theimage of the door on the film will be the fihn strip to the corresponding position onmaximum correct value corresponding to the top dial of the calculator as shown inthe point b on the film strip. Fig. 6. It will be noticed that the correct
From the foregoing it will be seen that film range for the indicated shutter speed
the exposure meter is designed upon sound and aperture lies between the "Darkest and
scientific principles and that with its aid Brightest Object" arrows.
the density of negatives can be readily pre,
determined. Several methods for accom, Let us assume the scenri is to consist of
plishing this result are described in the fol, a limestone building and a few well lighted
lowing pages. trees with grass in the foreground. The
brightest object is the stone work in the
sun which, let us say, has a brightness of
200 candles per sq. ft. and the darkest ob,
BRIGHTNESS RANGE METHOD ject is the trunk of a tree which has a
brightness of say 2t candles per sq. ft.; This is probably the most important and both of which are determined by using theuseful of the various methods of using the
meter. It not only gives correct exposure, meter close to the objects.
but also provides means by which the pho, In making this measurement it is neces,
tographer may have in the developed 6lm, sary to get close enougir to the object soany desired density within the film exposure that no light from any other source reacherrange.
[20] [ 21 ]View original page 13Page 14 · Read text
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the sensitive_ plate of the meter. A good
ruie is to hold the meter so that its distance
from the object is no greater than the least
dimension of the object. Care must alwayr
be taken to stand in such a position that
the body of the photographlr does not
interfere with the natural illurr,rination of the
object being measured. The meter may be
placed at any angle to the object without
detriment. A simple method for determin,
ing the correct location of the instrument
is to move it back and forth slightly, and if
the meter is properly located this displace,
rnent will not appreciably change its in,
dicatron.
L -" )View original page 14Page 16 · Read text
www.butkus.us Further, assume we are using a high SCENES BEYOND THE FII.M RANGE
speed )rthochromatic film having a speed So far we have discussed scenes in which
value of 15 to which the white dial arrow the brightest range lies well within che film
is set. Then if the brightness range, range, that is, less than 128 to 1.21.200, is placed at the low end of the film
range, i.e., with the darkest object arrow There are many scenes, however, in
set to 25 as shown in Fig. 6, and we use which the brightness range greatly eiceeds
any exposure indicated say l/30 second at the film range and the photographer, with,
f/16, we will obtain a negative having a out means for determining the facts, won,
density variation corresponding to the part ders why he fails to obtain a pleasing nega, tive. Such scenes are, for example, ( 1) aof the film strip from M to N, or a nega,
tive of low average density.. road in the woods with patches of sunlight on the road adjacent to deep shadows
Again, if we set the brightness range, among the trees where the measured bright,
12r.200, midway in the 61m range as shown ness may be 500 candles per sq. ft. and
in Fig. 7 and use any exposure indicated, candle per sq. ft. respectively, or (2) a
say 1/30 second at f./8, we will obtain a waterfall in a wooded and rocky area, where
negative having the densities lying between the foam may reach a brightness of 500
"O" and "P" on the film strip, which gives candles per sq. f.c. and the shadows on
a negative of average density. Again, plac, rocks and trees may be as low as 1, or (3)
ing the brightness range, 2r.200, at the top interiors where portions may be lighted by
of the correct film range as shown in Fig 8, direct sun or sky light and the rest in deep
by setting the brightest object arrow at 200 shadow.
and using any exposure indicated, say I/25 It is obvious that since these scenes ex,
second et f/4.5, then the fiim will have the tend beyond the film range, a theoretically
Imaximum safe density as shown in the film II correct negative cannot be made and thestrip from "R" to "S" and a slow printing only recourse is a compromise. It must
61m will result. not be assumed, however, that attempts to
photograph such scenes are doomed to
It is preferable to keep the density about failure, as it is readily possible to obtain
average or below as this gives better print' the most pleasing artistic ellects if means
ing and enlarging properties. are available for obtaining accurate data
for the exposure. The reason for this rs
that the human eye cannot adapt itself to
1 [26] 127View original page 16Page 17 · Read text
appreciate detail simultaneously in areas of Attention should be called to the factruch great difrerences in brightness. The that when the method just described is used
exposure data cannot be determined by the where very strong contrast eriats such as a
eye but are readily furnished by the Weston white dress against a dark background, and
Exposure Meter and the actual exposure it is set to the Brightest object arrow, an
given depends upon the particular lighting undesirably great density and halation may
effects desired and in this the photographer result. The latter may sometimes produce
must exercise his judgment and artistic taste. the desirable artistic efect of brilliance. but where it is undesirable then it is oreferable
For example, take the roed in the woods. to place the white object at a lowir density
If the picture is intended simply es a on the film range. For example, the Bright,general scene then it is desirable to show est object arrow may be set to say 800,
detail in the trees and allow the sun spots placing the dress at a lower density and
perto extend in the overexposed regions. The allowing all objects under 6.t candles
Darkest object arrow may be set at 1 candle sq. ft.-to be-underexposed. One.can judge
per sq. ft. which overexposes a4- objects the effect of these compromises by explor,aborre 130 candles per sq. ft. This may ing for objects having a brightness less than 6.i candles per sq. ft., that is, the objectgive an unpleasant chalky effect to the high
Iightr in piints and a comprom-ise may be brightnessarrow. indicated by the Darkest objectm"d" by setting the Darkest object arrow
ato 2.5, underexposing all objects having
lower brightnesJ, and overexposing all ob' EFFECT OF COLORjects higher than 320 candles per sq. ft. In determining the brightness of objects,
On the other hand, if the object is to some consideration must be given to the
take a portrait of a person on the wood's kind of film used. Orthochromatic film such
road, for example a girl in a white dresg, as Verichrome and Plenachrome are not
then all other larts of the scene must be sensitive to yellow, orange and red, so that subordinated to this object. In such a case for such films, objects of these colors, while
it is preferable to measure directly the possibly bright to the eye, will be dark to brightness of the dresr and if the Brightest the film. This, however, is not very trou, scencs oblict arrow is set to this vaiue, say 320 blesome in practice for out,of,door candles per 5q. ft. one must be content with for the reason that most objects have colors underexposu.L f or all objects lower than mixed with considerable gray, due to weath, ering, which reflects enough white light to
2.5 candles per sq. ft. give a reasonable density on the film.
[28] [2eIView original page 17Page 20 · Read text
www.butkus.usshould be directed slightly downward so MISCELLANEOUS
that thc imaginary 60" cone area covered INFORMATIONby the sensitive plates does not cxtend into
the sky area. Apernrre or f/Numbers
Before the erposure can be finally de, The I numbers on a camera are basedtermined when using trhe average brightness upon the focal length of the lens, that is
method it is necessary to decide upon the upon the distance between the lens and
character of the lcene. The top dial of the the film when the camera is focussed for
calculator divides all such scenes into three photographing distant objects. For using
general classes, as follows: the exposure meter, the f values as marked
A-Distant, weak contrast. on the camera are sufficientlv close for all
lens B-Normal. scenes located at a distan." i.o- the
C-Dark or strong contrast. exceeding 10 times the focal length of the lens, which is usually engraved on the lens The method of making exposures using mounting, or can be readily measured. Foreither of these three scene arrows will not example, when using a lens of say 4 inch here as it was described inbe repeated focus, marked correct are the I numbers I.Chapter scenes inches all or at a distance for of 40
more from che lens.
For ordinary cameras the efect upon f numbers due to distance need not be con, IMPORTANT sidered. For those having cameras with
It should be remembered when using the e.xtension bellows, or when taking close,
$/eston Exoosure Meter that it does not ups, enlarging, copying, etc., the actual f
give a singli definite correct exposure, but number in the camera can be found by com,
a range of correcc exposures, where one puting the ratio of the distance from the
may select any exposure within the correct lens to the scene, to the focal length of
range to give the most desirable density of the lens and then multiplying the marked f
film. For this reason the indicated shutter number by the factor given in the follow,
speed and aperture obtained by using the ing table:
various methods outlined will of course not Distance Ratio Factorbe the same, but the resulting negatives rYz '3 will have densities lying within the correct 2Z
exposure range but possibly of difering 3 l.t average densities. 4 t.3
6 t.2 10 1.1
[34] [ 3r ]View original page 20Page 27 · Read text
' Z,EP(O SETTING
I OF INSTRUMENT POINTER
When no light reaches the "electric eye" Fin the back of the Exposure Meter the in'
strument pointer should rest directly over I
the zero position on the scale.
If this is not the case, and there is no
electrostatic change on the giass (see page I
3), then the pointer can be readily set to
its zero position by slightly turning the
zero corrector located on the right side of
the meter directly below the calculator dial. F
When making this correction place the
meter back downward on some opaque ob'
ject, as a card or a book so as to exclude
all light f rom the photoelectric cell, and
hold it at an angle of about 4i'.
NOTICE
The manufacturer has endeavored tocompile accurate data on the various emul' fsioni but obviously can not guarantee the
products of other manufacturers. ' Since the so'callcd speed value of anemulsion depends somewhat upon the kind $
and method- of development and also upon
the density to suit requirements,-we-values recom'mend thai the speed to be used be
determined by tiial using the values tabu'
lated as a guide.
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