Gossen Digipro F2 H261A Manuel D’Utilisation
Codes de produits
H261A
5
4
Recording Medium
Dynamic Range [EV / f-stops]
Digital reflex camera 100 ASA 10
400 ASA 9
Digital compact camera 100 ASA 8,5 … 9
400 ASA 7,5
Black-and-white negative film
11 … 13
Color negative film
8 … 10
Color transparency film (slide)
6 … 8
Reproduction Medium
Dynamic Range [EV / f-stops]
Monitor
8 … 10
Digital projector
9 … 12
Slide projector
8
Photo paper
4 … 6
Photo printer
5 … 8
MEASUREMENT METHOD
Incident Light Measurement
External exposure meters allow for high precision incident light measure-
ment, which is interesting for portrait, object and fashion photography.
They measure and analyze light which strikes the subject, regardless of
its reflectivity. Complete control of lighting contrast leads to well-balanced
exposure results and allows for targeted use of the available dynamic
range. And the meter only takes illuminance into consideration – not object
brightness. The user is able to count on obtaining correct evaluation, as well
as good results, with both brighter than average and darker than average
subjects: optical influences which could lead to erroneous measurement
data are eliminated automatically by external exposure meters. Even objects
which greatly deviate from the middle gray tone are reproduced with correct
color and tonal values, as long as white balancing is correctly executed for
the digital camera.
ment, which is interesting for portrait, object and fashion photography.
They measure and analyze light which strikes the subject, regardless of
its reflectivity. Complete control of lighting contrast leads to well-balanced
exposure results and allows for targeted use of the available dynamic
range. And the meter only takes illuminance into consideration – not object
brightness. The user is able to count on obtaining correct evaluation, as well
as good results, with both brighter than average and darker than average
subjects: optical influences which could lead to erroneous measurement
data are eliminated automatically by external exposure meters. Even objects
which greatly deviate from the middle gray tone are reproduced with correct
color and tonal values, as long as white balancing is correctly executed for
the digital camera.
Flash Measurement
Where several flash units or a combination of ambient light and flash is
used, exposure meters which are integrated into the camera are inadequate,
because all of the sources of light which illuminate the scene have to be
individually evaluated and added up. External exposure meters are capable
of measuring individual flashes, calculating multiple flashes in the event of
insufficient flash power, and analyzing the ratio of flash to ambient light –
even where several sources of light interact with each other. A second, and
much greater benefit, results from using the meter to adjust the lighting
conditions of the individual sources of light to each other. This makes it
possible to use flash as a creative means, and to set up any desired lighting
mood quickly and repeatedly with any flash system and light shaper.
Evaluation of the ambient light ratio makes it possible to adjust fill-in flash
for outdoor use, or as the main source of light. Tedious experiments with the
power settings of individual flash units are thus a thing of the past.
used, exposure meters which are integrated into the camera are inadequate,
because all of the sources of light which illuminate the scene have to be
individually evaluated and added up. External exposure meters are capable
of measuring individual flashes, calculating multiple flashes in the event of
insufficient flash power, and analyzing the ratio of flash to ambient light –
even where several sources of light interact with each other. A second, and
much greater benefit, results from using the meter to adjust the lighting
conditions of the individual sources of light to each other. This makes it
possible to use flash as a creative means, and to set up any desired lighting
mood quickly and repeatedly with any flash system and light shaper.
Evaluation of the ambient light ratio makes it possible to adjust fill-in flash
for outdoor use, or as the main source of light. Tedious experiments with the
power settings of individual flash units are thus a thing of the past.
Use of the Available Dynamic Range –
Optimized Workflow
Metrological analysis of both illumination and the subject make it possible
for the photographer to take ideal advantage of the available dynamic range
of the recording sensor and the output media right from the start. Adaptati-
on by means of tedious post-processing is unnecessary and the fast-paced
workflow associated with digital photography remains unimpeded. Suitable
measuring functions include:
for the photographer to take ideal advantage of the available dynamic range
of the recording sensor and the output media right from the start. Adaptati-
on by means of tedious post-processing is unnecessary and the fast-paced
workflow associated with digital photography remains unimpeded. Suitable
measuring functions include:
Contrast measurement:
subject contrast from the brightest to the darkest areas of the
subject with detail
subject with detail
Mean value generation:
based on measured values from important areas of the subject
Zone measurement:
assignment of brightness values to defined gray values
Reflected Light Measurement
Where reflected light measurement is concerned, the exposure meter
acquires light reflected from the object to the camera from the standpoint
of the photographer. This value, based on all of the various reflective objects
within the image, is used as a mean tonal value for which required exposure
is calculated. Tonal range, color, contrast, background brightness, surface
structure and reflectivity of the objects influence the measurement results,
although they are not taken into consideration in evaluating the subject.
Monochrome subjects are reproduced in neutral gray with this measuring
method. A bright subject reflects more light and is represented as darker.
A dark subject reflects less light, and is thus represented as brighter. In other
words, if a white and a black car are photographed, both images will depict
the same gray car.
Reflected light measurement of a gray chart in close proximity to the
subject delivers more precise results because the gray chart reflects
exactly the same light component to which the exposure meter is calibrated.
However, this measurement is complicated and in many cases impractical.
acquires light reflected from the object to the camera from the standpoint
of the photographer. This value, based on all of the various reflective objects
within the image, is used as a mean tonal value for which required exposure
is calculated. Tonal range, color, contrast, background brightness, surface
structure and reflectivity of the objects influence the measurement results,
although they are not taken into consideration in evaluating the subject.
Monochrome subjects are reproduced in neutral gray with this measuring
method. A bright subject reflects more light and is represented as darker.
A dark subject reflects less light, and is thus represented as brighter. In other
words, if a white and a black car are photographed, both images will depict
the same gray car.
Reflected light measurement of a gray chart in close proximity to the
subject delivers more precise results because the gray chart reflects
exactly the same light component to which the exposure meter is calibrated.
However, this measurement is complicated and in many cases impractical.
Spot Metering
Spot metering is frequently integrated into modern reflex cameras, for
which the measuring range is indicated as a percentage of the image area
(sensor). The angle of acceptance depends on, and changes along with,
the lens’s focal length. External spot meters have a fixed, 1° angle of
acceptance and are capable of measuring small areas very accurately
within a complex scene, and it’s also possible to generate a mean value by
taking several measurements.
Spot metering is used when unreliable values are provided by reflected light
measurement or where incident light measurement is not possible. As a rule,
this involves scenes with objects at a great distance, backlighting situations,
extreme differences in brightness, reflective surfaces or a moving main subject.
which the measuring range is indicated as a percentage of the image area
(sensor). The angle of acceptance depends on, and changes along with,
the lens’s focal length. External spot meters have a fixed, 1° angle of
acceptance and are capable of measuring small areas very accurately
within a complex scene, and it’s also possible to generate a mean value by
taking several measurements.
Spot metering is used when unreliable values are provided by reflected light
measurement or where incident light measurement is not possible. As a rule,
this involves scenes with objects at a great distance, backlighting situations,
extreme differences in brightness, reflective surfaces or a moving main subject.
The Histogram
The histogram depicts the static distribution of an image’s tonal values.
Relative to brightness, the camera arranges all of the pixels along a horizontal
scale from 0 (black) to 255 (white). The height of the individual line indicates
the number of pixels of identical brightness. The fine lines which are very
close to each other may result in a gentle curve, a jagged mountain, a pi-
cket fence or a combination of any two or all three. A histogram provides
information regarding the distribution of tonal values within the image,
but does not offer any indication of lighting conditions, the ambient light to
flash ratio or whether or not the object is correctly illuminated. An external
exposure meter is used to this end in order to achieve best possible and
above all repeatable, results as quickly as possible.
Relative to brightness, the camera arranges all of the pixels along a horizontal
scale from 0 (black) to 255 (white). The height of the individual line indicates
the number of pixels of identical brightness. The fine lines which are very
close to each other may result in a gentle curve, a jagged mountain, a pi-
cket fence or a combination of any two or all three. A histogram provides
information regarding the distribution of tonal values within the image,
but does not offer any indication of lighting conditions, the ambient light to
flash ratio or whether or not the object is correctly illuminated. An external
exposure meter is used to this end in order to achieve best possible and
above all repeatable, results as quickly as possible.
Contrast Measurement
Subject contrast designates the ratio between the brightest and the darkest
portions of the subject which are important to the image. This is ascertained
by means of close-up or spot metering and is specified in exposure values or
f-stop steps. One exposure value is equal to one full f-stop. Subject contrast
is the result of different reflective characteristics of individual portions of the
subject, and lighting.
If subject contrast exceeds the dynamic range of the recording medium,
i.e. the total number of brightness levels which the medium is capable of
reproducing. The bright or dark parts of the subject appear showing no detail
and cannot be improved by means of post-processing. An overview of the
dynamic ranges of various recording and reproduction media are listed below.
portions of the subject which are important to the image. This is ascertained
by means of close-up or spot metering and is specified in exposure values or
f-stop steps. One exposure value is equal to one full f-stop. Subject contrast
is the result of different reflective characteristics of individual portions of the
subject, and lighting.
If subject contrast exceeds the dynamic range of the recording medium,
i.e. the total number of brightness levels which the medium is capable of
reproducing. The bright or dark parts of the subject appear showing no detail
and cannot be improved by means of post-processing. An overview of the
dynamic ranges of various recording and reproduction media are listed below.