Krzys
Well-known
I have seen that the Bessa meters its 18% grey shutter curtains. Is this essentially the same as spot metering off a grey card?
Metering
- Thread starter Krzys
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Chriscrawfordphoto
Real Men Shoot Film.
No. The lens projects the scene you are shooting on to the curtains, so it has the same problems as all reflected light meters...bright subjects fool it as do dark ones. Metering a grey card is different because the grey card faces the camera and you read the light hitting the subject. the bessa's meter, like all built in meters, reads the light that reflects off the subject.
Roger Hicks
Veteran
No.
Essentially you're metering the reflection of the scene in front of you.
Do a thought experiment. Black cat in coal cellar; polar bear in snow. The light falling on both is the same (a case for incident metering -- there is almost never a case for spot metering a grey card). The light reflected from the two probably differs by a factor of 10 or more -- and that is the light that is being focused on the shutter curtain, to be read by the in-camera meter.
See
http://www.rogerandfrances.com/subscription/ps expo neg.html (neg exposure)
http://www.rogerandfrances.com/subscription/ps expo slide.html (slide/digi exposure)
Cheers,
R.
Essentially you're metering the reflection of the scene in front of you.
Do a thought experiment. Black cat in coal cellar; polar bear in snow. The light falling on both is the same (a case for incident metering -- there is almost never a case for spot metering a grey card). The light reflected from the two probably differs by a factor of 10 or more -- and that is the light that is being focused on the shutter curtain, to be read by the in-camera meter.
See
http://www.rogerandfrances.com/subscription/ps expo neg.html (neg exposure)
http://www.rogerandfrances.com/subscription/ps expo slide.html (slide/digi exposure)
Cheers,
R.
Juan Valdenebro
Truth is beauty
Spot metering a gray card can be imprecise because of its placement (angle) in relation to sun or camera.
If you have time for a gray card, it's a better idea to use that time for an incident reading instead.
Cheers,
Juan
If you have time for a gray card, it's a better idea to use that time for an incident reading instead.
Cheers,
Juan
FrankS
Registered User
payasam
a.k.a. Mukul Dube
Juan and Frank, I used the "grey card method", using the palm of a hand and adding one stop, over long years when I had no incident meter. Works well in practice: and I was shooting mostly Ektachrome at the time. One can also use white paper and add 2.5 stops.
The Bessa's meter, incidentally, does not measure the "reflection" of the whole scene. It assigns more weight to the centre, and this is illustrated on the Cameraquest site. A Dutch engineer named Frans de Gruitjen did the work.
The Bessa's meter, incidentally, does not measure the "reflection" of the whole scene. It assigns more weight to the centre, and this is illustrated on the Cameraquest site. A Dutch engineer named Frans de Gruitjen did the work.
Juan Valdenebro
Truth is beauty
Payasam,
Yes, it can work OK if the sun (or light source) is behind you (perpendicular to the card) or close to that, but as the light starts coming from angles getting closer to the plane of the card, things become a different case. Again, we can learn to handle those cases to place the card differently and recalculate our reading, but I certainly find incident light metering a much more absolute concept...
Cheers,
Juan.
Yes, it can work OK if the sun (or light source) is behind you (perpendicular to the card) or close to that, but as the light starts coming from angles getting closer to the plane of the card, things become a different case. Again, we can learn to handle those cases to place the card differently and recalculate our reading, but I certainly find incident light metering a much more absolute concept...
Cheers,
Juan.
payasam
a.k.a. Mukul Dube
I agree that measuring incident light is the best method. However, when I was your age the only meter I had was the reflective one built into my SLR, so I had to play a simple trick to turn it into an incident light meter.
I must also point out that how an incident light meter is held can make a considerable difference to its readings. Nothing is perfect or fool-proof.
I must also point out that how an incident light meter is held can make a considerable difference to its readings. Nothing is perfect or fool-proof.
Juan Valdenebro
Truth is beauty
You're right. The angle of the meter can make a difference, as the light source angle, and its position over the horizon as well... I retract: absolute is a word I shouldn't really use for any kind of metering.
