The point of a light meter?

silversprej

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Hi,

I recently got a gossen digisix into my posession, and today I tried it out. To my dissapointment it actualy works not nearly as good as the built in meter of my Nikon D200, not even as good as the EOS350D. It seems like it's point-metering, and the overall exposure is just not right. Is there a point using a seperate light meter only if you don't have one built into the camera, or am I doing something wrong?

I would like to use it with my older analouges, but as it is I don't trust it's result enough.
 
When you click the light meter, are you pointing the dome directly at the camera and the light meter is right at the location of your subject? If you are simply taking taking some wide open shot, a light meter may not help. However, great for a specific subject with constant lighting.
 
Thansk for your fast replies!

@Mike: How am I supposed to calibrate it?

@Ryan: I was just pointing it at the subject. Am I supposed to point it at the camera? The user manual doesn't say (perhaps they assumed everbody buying it should know :p)

Still, I wonder abour the metering method that is used. Is it supposed to be better then the built in methods in some way (in what way)?
 
It is the same (more or less) as the one in your camera. Just as with any photographic equipment it's a matter of how familiar you are with your gear. I would go to here and see if you can find a manual for this meter and learn how to use it better. Might come in handy someday when you never know when it might come in handy. Yup, no idea where I was going wiht that last one. Anyway, enjoy it.
 
If it has a white dome, it is an incident meter ...this means it is measuring light falling on it.
So, hold the meter directly in front of the thing you want to photograph and point it at your main light source (usually the sun)...NOT at the camera.
 
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The idea of the dome is to measure light from all relevant angles* when the axis of the dome is pointed at the camera and the meter is being used to determine exposure. If the meter is fitted with a flat receptor, or a shrouded dome**, it can be pointed directly at the source to determine the contribution from that source.

The Digisix has a sliding dome. With the dome slid out of the way it can be used as a wide-area reflective meter - ie you point it at the subject. With the dome in place you position it at the subject and point it at the camera - or use it in an equivalent location and orientation. For example if the subject is in full sun you can place the meter in full sun and point it in the same direction as it would be if it was at the subject pointing at the camera.

Most scenes have different levels of illumination - for example sun and shade. With slide film and digital cameras it is usually best to expose for the brightest parts of the scene. With an incident meter this means that you use it in the brightest illumination. If you were using negative film you would probably meter in the shade, so that the shadows were correctly exposed. By measuring the difference between the highest and lowest illumination you can estimate the brightness range of the scene - you add five stops to the difference in meter readings.

That's all a bit condensed, so please ask if you would like anything to be elaborated on.

*Domes are considered to have a cardioid (heart-shaped) response and they read light arriving from the side and from partly behind - but they have zero response to light from directly behind.

**Flat receptors and shrouded domes are considered to have a cosine response - they have zero response to light coming from the side and from behind. This is very similar to using a grey card.

Best,
Helen
 
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...By measuring the difference between the highest and lowest illumination you can estimate the brightness range of the scene - you add five stops to the difference in meter readings...

<snipped>

I don't quite understand that. Where and why are you adding five stops?
 
Where and why are you adding five stops?

Here's an example from the last architectural shoot I did.

In full illumination (the sun) I got an incident reading of 1/15 s at f/32 and in the shadiest part of the scene I wanted detail in I got an incident reading of 2 s at the same aperture. That is a five stop difference in illumination level. I add five stops to that to get ten stops, so that suggests that the scene brightness range could be about ten stops. (It wasn't, in this case, for reasons I will explain later)

Why five stops? That is the maximum likely range of reflectance of the objects in the scene. If everything in the scene was somehow under the same illumination, with no shadows, the scene brightness range would be no more than about five stops.

What we think of as a bright white object typically has a reflectance of 90%. Very bright objects have a reflectance of around 96%. (These figures disregard specular reflections). Very dark objects have a reflectance of around 3%, though some are darker than that. The difference between 3% and 96% is five stops (3, 6, 12, 24, 48, 96). The scene brightness range (SBR) is created by a combination of different lighting levels (eg sun and shade) and by different reflectance levels (eg black and white).

Knowing that you are able to make adjustments to the simple 'plus five' method. If something in the scene has specular reflections that you wish to keep detail in (for example an aluminium grain elevator or an aluminium-painted roof) the SBR could be higher. If there is nothing dark-coloured in the shadows the SBR could be lower. That was the case in the example I gave. Nothing in the deepest shade was below about 6% reflectance, and so I estimated the SBR at one stop less than the 'plus five' method - ie nine stops of SBR. I knew that I could place that on the film's characteristic curve (Portra 160NC) while staying well clear of the toe* (the lowest exposure the film will respond to) and the shoulder (the highest exposure the film will respond to) and thus having clean detail everywhere in the scene.

Best,
Helen
 
As others have mentioned, a hand held light meter with a dome is an incident light meter, meaning it reads the light falling on it. The meter in your camera is a reflective light meter which means it reads the light reflecting off your subject. This is why you need to hold the light meter in front of your subject and point it at your camera, not point it at the subject. Pointing it at the subject is how a reflective light meter reads light.
 
As I mentioned above, the Digisix may be used as an incident meter or as a reflective meter.

Best,
Helen
 
I feel the same as the OP, I bought a Sekonic L308S and I don't see that it does any better than my built in meter. The only time it would be worth it is using with strobes, but since with this one you have to plug in the sync cord and the back and forth - I would rather use the trial and error method myself....I am sending my meter back.
 
I feel the same as the OP, I bought a Sekonic L308S and I don't see that it does any better than my built in meter. The only time it would be worth it is using with strobes, but since with this one you have to plug in the sync cord and the back and forth - I would rather use the trial and error method myself....I am sending my meter back.

If the meter is doing better than your camera, then you have a problem with the camera. The the reflective reading from the meter and your camera should be identical. The reasons for having a meter are (1) because it eliminates the need to move your camera around to take spot readings of the subject, and (2) (Assuming you got one which was capable of doing incident readings) so that you can take incident readings and tune your lighting and or subject positioning.
 

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