Hasselblad H2F Manuel d'utilisateur télécharger pdf (Page 37)

Average

(45 x 37 mm) ≈ 70%

Centre weighted

(23 x 20 mm) ≈ 20%

Spot

(diameter 7.5mm) ≈ 2%

Metering method

There are three metering methods available. All three are reective methods (measuring the light

reected o various selected parts of the subject according to method) and are through the lens

(TTL). These have the following designations (with their respective LCD symbols):

— Average

— Centre weighted

— Spot

Average: Commonly used for ‘average’ light situations where there is no particular dominance of

light or dark areas across the tonal range. Takes into account approximately 70% of the image seen

in the viewnder.

Centre weighted: Emphasises the central section of the focusing screen equivalent to approxi-

mately 20% of the image. This provides a balanced assessment and is a typical choice where the

main subject is in the centre of the image.

Spot: The sensitive area is equivalent to approximately 2% of the image area (the central spot on

the viewnder screen). Any parts of the image outside of this area will not aect the exposure read-

ing. This provides a very accurate measurement of specic tones.Typically used in the zone system

and similar light measuring situations where maximum control is required. Also excellent for tonal

comparison measurements. The spot mode can display ‘zones’ instead of EVs in the viewnder LCD(

see Camera Options).

 Exposures are displayed on the grip LCD to within 1, 1/2 and 1/3 EV tolerances (dependent

on setting). This means that ‘half-stops’ are shown in a form that can diﬀer from more

traditional displays. For example, the position between f/ 8 and f/11 is displayed as f9.5 and

likewise the position between 1/30s and 1/60s is displayed as 45. Therefore a display show-

ing ‘f 9.5 45’ simply means ‘f/9.5 at 1/45 second’. The appearance of an ‘s’ after the shutter

speed signiﬁes whole seconds so, for example, ‘45s’ on the display signiﬁes an exposure time

of 45 seconds, not 1/45.

Some methods and modes are much more suited to various situations and applications than oth-

ers, while some depend to a greater degree on personal preference and ways of working. A discus-

sion of the points to consider in this context is beyond the scope of this manual. If you are not sure

about choice, please check in other general photographic literature for a fuller explanation. Also

check our website occasionally – www.hasselblad.com – for articles and discussions concerning

such matters.

Remember that exposure congurations are only applicable to the speed of the lm in use. Ensure

you have the correct setting on the lm magazine!

Since the light measuring system is TTL, lter factors, lens extension / extension ring factors, etc, are

automatically taken into account for average purposes. However, some combinations of methods

and equipment can cause slight discrepancies for various reasons and therefore for critical work

you should make alternative exposures to suit personal preference.

Light metering and exposure control

Two primary factors have to be considered when making exposure control choice, namely, metering

method and exposure method:

Metering method determines in which manner the light measurement is made and how much of

the image is taken into account( Average, Centre Weighted and Spot).

Exposure method involves the parameters and deciding factors about how the light measure-

ment is translated into aperture and shutter speeds. Here the choice is about the camera controls

and their eect on the result or suitability for the subject. Included in this choice is the type of auto-

mation too (Manual for 100% user control, Aperture priority, Program, etc for automated control).

1 2 ... 32 33 34 35 36 37 38 39 40 41 42 ... 85 86

Commentaires sur ces manuels

Pas de commentaire

Hasselblad H2F Manuel d'utilisateur Page 37

Commentaires sur ces manuels