Light meters
Exposure: Meters and Techniques User manual
User manual for Exposure: Meters and Techniques. 15 pages in English. Read the original PDF, download or print a copy without registration.
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- Exposure: Meters and Techniques
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- User manual
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- English
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- 15
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- Category
- Light meters
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Moving to the next larger full l-number at f /8, and U3A at l/11. Your choice should
(see full-stop differences, below) closes be based 0n the speed reguired to handle
down the opening and halves the amount of action, or the depth of field needed for the
light reaching the film. Opening up one fuf l scene. lf both aspects are important, you
compromise, or use a fasterstop (from say l/l! to l/81 doubles the may have to
amount. film that will permit combining a high speed
Equally important is the way depth of with small lens opening.
field (the zone of apparent sharpness before
and behind the point of focus) varies with EVSthe l-number chosen. In general, closing Exposure can also be stated in other ways.
down the lens increases the depth of field; The popular EVS (Exposure Value Scale) sys-
so does using a larger focusing distance. tem uses numbers from 0 to 18, and ex-
You may need a deep zone for landscapes, presses equivalent exposures by a single
but a narrow one to throw a distracting number. EV 12, for example, describes the
background out of focus in outdoor por- light-passing power of equivalent exposures
traiture. When choosing the proper /-number given in the previous paragraph.
for a particular distance, check the depth- Once the correct EV number is set, moving
of-f ield scale found 0n most adjustable to a different shutter speed also changes
cameras. the /-number (or vice versa) to maintain
the same exposure value. This brings an
WHICH G()MBINATION? added measure of useful automation, which
For any exposure pair, there are always can be discarded when necessary if the EV
a number of other shutter-speed, lens-open- scale can be completely uncoupfed to allow
ing combinations which allow the same using the camera in the more conventional
amount of light to strike the film. Such way. Following the rise of the systern, EV
equivalent exposures might be, l/500 at scales have been added to more meters,
l/2.8, l/250 at f /4, l/125 at I/5.6, l/60 and on some, it is the only scale used.
HXPEDSURE GONTROLS AT A ffifuAhdffiffi
SHUTTER-SPEED SYSTEMS
0lder Scale r/2 L/5 r/r0 uzs r/50 L/no v200 1/500 1/1000 (in seconds)
Linear Scale r/z r/4 r/8 r/r5 r/30 ua\ r/r25 r/250 1/s00 1/1000 (in seconds)
F.STOPS
Full stops I r.4 2 2.8 4 5.6 8 11 16 22 32
Third stops 1.1 1.3 1.5 1.8 2.2 2.5 3.2 3.5 4.5 5 6.3 7 9 10 l2-7 14 18 20 25 29
*#cView original page 4Page 6 · Read text
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TYPES OF METERS to make accurate readings, one may be
There are two basic kinds of photoelectric more advantageous than the other under
exposure meters-reflected.light and inci. certain specific lighting conditions. 0nfy you
dent-light types. Though either can be used can decide on which to use.
Digitally signed by mike butkus
DN: cn=mike butkus, o=orphancameras,
email=mike@butkus.org, c=US mike butkus ou=29,Date: 2019.08.20 19:28:43 -04'00'
REFLEGTANGE TVPE INCIDENT TYPE
These meters only measure light that is Incident meters; on the other hand, meas-
reflected from the subject toward the meter ure the amount of light falling on the sub-
and provide an average of the ilfumination ject, and are usually characte rized by a
received. Results; change as you shift the hemispherical light collector with a wide
r'*>.. meter from a light area and point the celf (l80-degree) angle of acceptance. This cre-
at a darker spot. Here, depending on your ates an artificial highlight whose brightness
point of view, is the advantage 0r disad- is measured by the meter. Such meters as-
vantage of this meter type. sume that the scene has a normaf range
A fairly narrow angle of acceptance is of tones, and are calibrated to produce an
desirable. To achieve this, the cell is re- exposure reading at a mid point.
cessed, or covered by a plastic, lenticufar Many photographers favor the incident
grid, which controls the angle and amount meter because it provides a uniform reading
of light received. A baffle may be used for that disregards the color of the subject
light controf; as well. The result is that the matter, and is also preferable for movies
angle of acceptance 0n a number of units and side- 0r backlighted subjects. 0thers
is about the same as the angle of view on a find it awkward when camera and subject
normal lens. are not in the same kind of light (see next
Most separate meters, as well as all those pages) and when the main subject is darker
buift into cameras, are of the reflectance or lighter than noimal.
type. In some, the needle indicates exposure To control the amount of light reaching
directly, in others a dial must be turned the cell beneath the collector, slides are
0r set. The "match pointer" system is often inserted and act as baffles in bright
common in semi-automatic, built-in meters. fight; one meter, however, has a variable
Conversion to incident readings is done by light valve. Most of these meters can be
means of a special opal plate. converted for reflectance readings.
,l
--View original page 6Page 7 · Read text
F,ISW TO NfiAKffi A FIEAIDING
\^/ITH REFLEGTED.
LIGHT METERS
AT THE CAMERA The usual method for dis-
tant scenes, 0r when you do not want to
move in closer. lt provides an over-all aver'
age of the scene. Always point the meter
slightly downwards to exclude excess sky-
light which can inf late the reading and
cause you to underexpose nonsky areas.
Where shadow detail is important in face or
scene, open up one stop for black'and-white
and negative color, a half stop for reversal
color.
AT THE SUBTECT For greater accu racy, move
in close and take a reading as shown at right. Hold the meter cell about 6-8 inches r# f\
from the subject, so no shadows are cast sj#by your hand or meter on areas being meas-
ured. This method is particularly suitable .\\f:l r*rA* K
for relatively small main subject areas
(faces for example) set against a much
darker or lighter background, when full ex-
posure of the main subject only is important.
THE SUBSTITUTE HAND METH0D When a
close-up reading would disturb the subject,
try a substitute reading with a similar ob-
ject, lighted identically. Professionals often
use their hand, holding the meter 6-8 inches
away s0 n0 shadows of meter or hand are
cast on the palm. Use the reading for bright
landscapes, 0r where light and middle tones
'detail in faceonly are important. For
shadows or darker main objects, open up one
stop with negative color and black-and-white,
a half stop with reversal color.View original page 7Page 8 · Read text
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\^/ITH INGIDENT-LIGHT
METERS
AT THE CAMERA You can make a reading at
isr shooting position if illumination there
the same as on y0ur subject. Hold the meter
out with light collector aimed at the lens,
along a line from the subject. The exposure
is full, but with lighter-than-normal main
subjects you need to close down one stop
for black-and-white, half to 0ne stop for
color. With darker-than-normal subjects,
open up similar amounts.
AT THE SUBJECT Whenever light 0n the
camera and 0n the subiect are not alike,
you must move in close enough to measure
the kind of light actually falling 0n the
scene, often found only at the subiect it-
self. Hold the meter as shown, with the
light collector aimed back at camera posi-
tion (except with sidelighted subjects dis-
cussed on the next page). The modifications,
given above, for lighter and darker subjects,
apply equally here, with both -;olor and
black-and-white films.
at SPEGTAL TECHNICIUES lighter- or darker-than-normal areas are
WHEN T0 TAKE TWtl READINGS lt is often some distance from each other in the scene,
best to take high and low close-up readings and light falling on each is different.
with a reflectance meter, and average the
results by setting exposure at their mid lF Y(lU CAN'T C(IMPR0MISE When the tone
point. This will generally give you detail in range is too great to fit within the scale
both light and dark picture areas, if no of black-and-white paper or color film, you
more than a six-stop difference exists with must shift exposure from the high-low mid
black-and-white, or a three-stop one in color. point, to favor lighter or darker areas. The
Incident readings provide an average for decision is generatty a pictorial one. In
scenes with a normal range of tones, but color, however, the rule is not to wash out
two readings can be useful when important significant light areas through overexposure.View original page 8Page 9 · Read text
,^\
I ffiASgffi LIGI.{THNffi S*TUJITTSruS
FRONTLIGHT, ANGLE- as at noon, toplighr falls on your subject.
can LIGHT, TOPLIGHT Any of the reflected-meter techniques
These three lighting situations follow the be used if shadows produced by angle- and
sun. When it is behind the camera and low toplight are taken into account. (See H9w
in the sky, fro ntlighting is present; a sun to Moke o Reoding.) lncident readings can
higher in the sky (often somewhat to one be used "as is" excepting when the main
side of the camera) signals onglelighting; subject is much lighter or darker than nor-
finally, when the sun is directly overhead mal. (See previous page.)
SIDELIGHTING
Just as the term implies, the sun is al- With black-and-white, and negative color,
most directly to one side of the subject, open up one stop more than the reading
casting deep shadows and creating bright indicates; with reversal color, a half stop.
highlights. An incident reading is preferable For highlight detail only, in portraiture,
for full detail in both highlight and shadow use the reflected-meter highlight reading,
areas. Hold the meter in the middle of the or hold the incident meter at the highlight
subject's face, making sure the collector side of the subject's face and point the light
receives some of the light falling 0n the cof lector directly ot the light source.
highlight side as well as on shadow areas.
When readings for landscapes and views are
made at the camera, aim the light collector
back at a spot halfway between the sun
, and camera position. In either case, open
up half to one stop more than the reading
indicates, if the subject is darker than
normal.
ldeally, two readings should be made
close up with a reffectance meter to find the
mid point for full detail in both shadow and
highlight areas (see Speciol fechniques on
the previous page). Because this is often
impossible or impractical, a substitute read-
ing can be made from a sidefighted hand.View original page 9Page 10 · Read text
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I
BAGl(LIGHTING
Striking effects can be obtained when of an incident meter directly at the sun.
the sun is behind your subject. The first of These readings will provide a full silhouette;-f- these calls for full exposure of shaded opening up one stop more will give a partial
areas, and an incident reading is always one. For various other effects between full
preferable. Simply use one of the appro- exposure and f ull silhouette, change the
priate methods already described--at-the'- reading for either situation further. But re.
camera or at-the-subject techniques-and member that the brightness range is usually "'you aim the light collector back at the camera too great for to record both ends of
position. As usual, with darker-than-normal the tone scale fulty.
compfexions, or :landscapes with important
dark areas, open up half to one stop.
It is possible to take reflected.light read-
ings if you measure only the shaded area, :{ and shield the light-sensitive cell from all
I * -'.. backlight. A substitute hand reading is also
feasible if the hand is held s0 that it is f:-E Lr!
a backlighted, and you open up half to one ffi
stop more whenever you want detail in ' -'t- ,*"7
darke r-than-normal subjects.
At the other extreme is the silhouette, e,r''. ijr'r"
where no detail appears in shaded areas.
Either type of reading can be used. Point
the cell of the reflected meter at the sky,
but not at the sun; 0r aim the light collector
ADAFTING A TVIETHR
It's a great advantage to be able to adapt :using your adapted meter for important pic-
a reflectance meter for incident readings, tures. Test results will show if you need
and vice versa. Conversion to incident opera- to compensate in srt wa)r for your equip.
tion is usually done by attaching an opal ment or methods.
plate 0r unit over the light-sensitive cell. f ncident meters are converted to reflec-
However, not all incident attachments are tance use by removing the light collector
as efficient as the hemispherical lig:ht col- and substituting a grid. There is some loss
lectors on most incident meters, with their in sensitivity, which may be annoying in
l8O-degree acceptance angle. lt's wise to low-light situations. Again, tests should be
run some tests with sidelighted and back- run to determine if any over-all compensa.
fighted subjects of avetage color, before tion in ;your exposure is needed.
-it !:.. .: ,'View original page 10Page 12 · Read text
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ffif;L"Fffiffis
All filters hold back some of the light, or as the amount to open up the lens.
so exposure must be increased according to ln block-ond-white, the increase is
the filter used. 0nly a few, like the Skylight, stated as a filter factor. The chart below
haze, and UV, have so little effect that no translates these into the number of /-stops
exposure change is required. to open up the lens. You can also divide the
ln color, the increase is usually givgn as factor into the exposure index, and reset the
a new exposure index to use with your meter, meter before taking a reading.
Filter Factor t.2 1.5 t.7 2 2.5 3 4 5 6 8 t2 16 25
2/g Amount to open r/s Tg I lr/s l2/s 2 2Yz 22/g- 3 3Vs 4 4Vt
up, by /-stops
ffiff-*ffiffim*L"$ps
o WHEN T0 INCREASE EXP0SURE No increase With a 50-mm lens at l/8, and a 200-mm
is required if you use a simple supplemen- distance from film plane to lens diaphragm,
tary f ens, marked in diopters (* l, + 2, +3, the effective l-number would be:
etc.), even if your lens is only inches away
1 '2.' four1^ stops from from the subject. f /8 x 200-mm orA, l/32; Additional exposure must be given if you 5g-** l/8. extend the lens-to-film distance (with a bel-
fows, tubes, or any other means) in order HOW T0 TAKE A READING There are two
to focus closer than about 8 times the focal schools of thought here. Some professionals
length of the lens. Light must now travel a strongly prefer an incident reading, while
longer distancei the intensity of illumination others favor a reflected reading with a
0n the film is reduced; and /-numbers no Kodak Neutral Test Card. lf the gray side
longer express light-passing powers of the (with l8-percent reflectivity) is held over the
lens. subject, parallel to the film plane, the meter
All this is corrected by using a new reading applies. When the white side (with
"working value"-the effective /-number- 90-percent reflectivity) is used, the exposure
with your meter. You can find it with one index should be divided by 5 before making
of the special calculator dials available, or a reading. Whether you take a regular inci-
by applying this formula: dent reading or select one of the reflected
l-number
Effective on lens "o, filmdiaphragmplane todistance bemethodsincreaseddescribedslightlyabove,for darker-than-normalexposure should
l-number: objects, decreased for lighter ones. Try a
.,
.:l-n ,,.. 'View original page 12Page 13 · Read text
number for one by 1.4 and use this newMULTTPLE FLASH
More interesting effects can be obtained number for figuring exposure; similarly, if
by using several f lashbulbs 0r electronic three lights form the main light, multiply
flash lights at the same time. ln most cases, the guide number for one by L.7. Special
there is only one main light, while others notes: Recommendations given above apply
act as fill, lighten the background, or provide to electronic flash if each light is separately
hair or rim lighting. Exposure, then, is based powered. When the power of one unit is
on the guide number for the main light only. fired through several heads, however, the
Should there be some overlapping of lights total light output is divided between them,
in front of the subject, try closing down and revised guide numbers, often given by
about one-third stop for color, and somewhat the manufacturer, must be used.
more for black-and-white. Unless you have worked with a specific
When two bulbs are aimed at the same lighting setup before, always bracket ex-
area from the same distance, and act to- posures-by half stops with color and full
gether as the main light, multiply the guide stops with black-and-white.
ffiffiqJ ffi#ffiffi e-"$ffi *-frY
. For softer illumination than with direct
flash or flood, bounce your light by aiming
the reflector directly at the ceiling, angling
it (as shown), or reflecting light off a light-
colored wall. Surfaces must, of course, be
pure white if you shoot in color, otherwise
an unpleasant color cast may show up in
your pictures; €ven a slightly y.ellowed
white, or somewhat bluish gray can spoil
color shots.
Exposure for bounced floods is naturally
by meter. With flash, guide numbers are
used, but in a slightly different-than-hormal
way. First, find the total distance from bulb
to ceiling (or wall), and from ceiling (or
wall) to subject. Then divide this figure into
the guide number used for direct flash.
Finally, open the lens an additional stop
to take care of illumination loss due to re-
flecting the light off a white surface. For
darker ceilings and walls, open up the lens
aperture a half to one full stop"View original page 13Page 14 · Read text
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F"HffiW Tffi MEffiAS{-SSEH CCIhITRAST
It's often usef ul to measure contrast then check the new setup in the same way.
when you're working with floods, s0 you The high-low reflected-light technique can
can alter the ratio of tones according to the also be used outdoors when you lower con-
limits of the color film, 0r the paper 0n trast by means of a reflector. The incident
which a picture will be printed. method outdoors, however, is as follows:
This is done by taking two readings. With take one reading for light falling on high-
a reflected meter, measure highlight and light portions, another for ilf urninalion reach-
shadow values; with an incident meter, point ing shadow areas. In each case, ,point the
the collector at the main light for one read- incident-light collector back at the camera.
ing, at the fill light for the other. A good This incident technique is particularly
maximum for color is a three-stop difference good for outdoor movies, when contrast is
between readings (an 8-to-1 contrast range); high. Place ref lectors s0 highlights and
in black-and-white, a six-stop difference shadows are in a 4'(or 3) to-l ratio with
(contrast range of 64 to 1). lf contrast is black-and-white, and about 3-(or ? to-l with
too great, simply move the lights till a more color. Keep measuring contrast till the -tones suitable relationship of is achieved; proper ratio is reached.
frtuTffiro&ffiffiffi ffiKSPffiSUFRH
I Unusual effects are obtained by using a about l/25 at l/8. Generally, a photoflood
red filter and infrared film: blue skies g0 exposure table is also included, along with
nearly black, green foliage a near white. guide numbers for infrared flashbulbs (no
Your meter, which responds only to visible filter is required and clear flash. Stop down
light, however, will be of little help with as much as possible, since infrared rays
invisible infrared rays. Use the recommenda- don't come to the same focus as visible
tions found in the film leaflet. The basic ' fight. lf your camera has an infrared focus-
exposure for bright, sunny landscapes is ing mark, be sure to use it.I
ffiww$ffiffi
Meters are used as much for movies as light tones should seem to be equally bright I for still photography, but preference changes in successive scenes. The artificial highlight,
considerably. Incident meters, for example, measured by the incident meter (see fypes
are generally best for all movie work be- of Mefers) makes this possible, while results
cause they permit balancing exposures for witlr a reflected meter are less standard, in
different scenes so there will be a consist- this respect, because they depend on where
ent density for light tones throughout. This the cell is aimed. 0therwise the reffected-
is particularly important when films will be light meter readings should prove to be quite
edited and spliced. Even-in unedited reels, satisfactory for movie work.View original page 14Page 15 · Read text
lf floods are used, incident readings and reduce the highlight shadow ratio.
should be mUde at sublect position, with the Placement of the ref lectors depends on
light collector aimed back at camera. maximum contrast desired. See also How
When contrast is high outdoors, it is tiest fo Meosure Confrosf, where ratios for
to lighten shadows by means of a reflector, movie film are discussed with greater detail.
TESTING A IWHTffifiN
To make sure your meter is functioning play. A slight amount of movement is normal,
properly: but it should not be excessive.
1. Cover the light-sensitive cell with your 4. Finally, test your meter under con-
hand; then see if the needle goes back trolled lconditions against a, similar meter
quickly and smoothly to zero position. Make that is known to be reliable in both bright
this test at least several times. Needle and low light. Check ref lectance meters
should not stick or jerk. with an evenly illuminated, smooth, matte-
white, 16x20 mounting board, holding each
2. lf the needfe does not return exactly meter cell about a foot away from the sur-
to zero position, look for the zero set-screw face, so n0 shadows are cast. With incident
on the meter, and turn it till the needle is meters, make sure collectors are positioned
directly over the zero mark when the cell is side by side, and are aimed at the same
covered, so no light can enter. point.
Meters check out if readings are n0 more
3. Still covering the light-sensitive cell, than one third of a stop away from results
shake the meter gently and check for needle with reliable equipment of the same type.
A$A AND WESTON SF3HHMS
Film ratings are given in the ASA scale rated at 50. Unit increases are by one-third-
system, where higher numbers stand for stop values. All this is also true of the
faster film. Moving over three boxes on the discarded Weston system. Equivalents are
scale doubles any value; thus a film rated for the numerous users of older Weston
at 100 is said to be twice as fast as o'ne meters, featuring Weston ratings.-+F
ASA I t.2 1.6 2 2.5 3 4 5 6 8 10 t2 16 20 25 32
Weston 0.75 I 1.2 1.6 2 2.5 3 4 5 6 8 10 12 16 20 25
ASA 40 50 64 80 100 rzs 160 200 250 320 400 500 650 800 1000
Weston 32 40 50 64 80 100 125 160 200 25A 320 400 500 65,0 800
f.L,,uF-rView original page 15Related documents and language editions
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