deferences reading on Minolta IV F

[yaacovk]

Hello.
usually i"m using to meter with the rangefinder accessory in AMBI mode when i meter at outdoor.
but when i try to meter with the white cup in the same condition
i have a different measure.
for example measure with the rangefinder accessory on T = 1/60
gives: f = 4.0.
with the white cup it gives me: 2.8
is some one can explain me what is the different?

thanks in advance.
Yaacov.

 

[sevo]

Your scenery obviously does not resemble a grey card. Or you are not placing the dome at exactly the spot where you metered the grey card. Or you had more complex lighting than a single grey card reading can evaluate.

In other words: Reflective and incident will rarely read the same value. And even if they do, it may mean that both are wrong - the biggest secret in the art of metering is knowing what to meter...

 

[Edward C. Zimmermann]

Hello.
usually i"m using to meter with the rangefinder accessory in AMBI mode

What is the "rangefinder" accessory? Do you mean the spot meter attachment?

when i meter at outdoor. but when i try to meter with the white cup in the same condition i have a different measure.

Do you mean the globe diffuser? That's for incident light measurements.

for example measure with the rangefinder accessory on T = 1/60
gives: f = 4.0.
with the white cup it gives me: 2.8 is some one can explain me what is the different?

Assuming you are comparing spot (reflected) with incident.. You are metering different things. In general I would NOT use the spot meter attachment. To get a proper reading one must read several points and average with a pinch of intuition and a heaping of experience. If done "correctly" it will, in general, yield a result under normal conditions not too terribly different than the incident measure. The point of spot reading is to get a handle on the scene contrast and to be able to measure from a distance. Most of the time one is better off measuring using the incident method. That's the technique most used in motion pictures--- an application where there is significantly less exposure latitude, high demands for consistency and where the cost of even small errors can be astronomical. Put bluntly: what's good enough for professional cinematography is surely sufficient for an amateur with a rangefinder camera.
Under some circumstances where the light is quite harsh a combination of both can, however, be useful. The Minolta has only one sensor but it has memory for up to 3 readings and an averaging function.

 

[sevo]

Most of the time one is better off measuring using the incident method. (...) Put bluntly: what's good enough for professional cinematography is surely sufficient for an amateur with a rangefinder camera.

There is however one significant difference - most amateur photography (almost all if we exclude on-camera flash) is done with whatever ambient light there is. In cinematography the lights are placed (under meter control) to illuminate the scenery very evenly - much more evenly or at least much more controlled than anywhere in the real world.

Arguably there is not that much point in metering what you cannot control, so incident is usually good enough for ambient lit photography. But using one global incident metering for the scenery is not going to give you as much control as using incident metering individually on each and every light source will do on a film set.