Wrong Metering in Specific Light

[thuggins]

I have noticed this at various occasions over the years. It has happened with in camera meters and hand held meters. I have seen it at high latitudes (Alaska, Orkney Islands) around mid summer, here in Texas in mid winter, and just recently in PA in late summer. In every case the sun is low (around mid morning) and pretty much directly from behind. Although the specific time and place vary widely, they all share a common component.

In each case the meter reads more light than there actually is. The reading is at least a stop high, sometimes more. Apart from the meter not "looking right" to the actual light, frames exposed to the meter reading will be notably under exposed.

My best guess is that is related to polarization, with the low rays striking the ground and being reflected back up to "add" to the direct light. Has anyone experienced this? Any theories on why it occurs?

 

[jeffreyg]

Check what the angle of acceptance of your meters are.. You indicate that your subjects are backlit. An incident meter or reading the light falling on the subject will probably help Also spot metering should be considered. The brightness of the sky behind your subjects might blow out some highlights if you are measuring deep shadows. The color and reflectence properties of your subject also matter. Depending on your subject a reflector might help.

http://www.jeffreyglasser.com/

http://www.sculptureandphotography.com/

 

[Vaughn]

Light meters do not act in a linear fashion with changing colors. The Zone VI modifications to some meters helped to reduce this.

Meters have memories -- if you point them towards the sun at any time, they will not read correctly for awhile.

Question...when photography with your back to the sun at the same time of day, do you get the same one stop underexposure on your film?

 

[Pieter12]

It's a backlit scene and your meter is reading the strong background light. Of course the subject will be underexposed--Photo 101.

 

[thuggins]

It's a backlit scene and your meter is reading the strong background light. Of course the subject will be underexposed--Photo 101.

No, it is not a back lit scene. The sun is directly from behind THE PHOTOGRAPHER!

Question...when photography with your back to the sun at the same time of day, do you get the same one stop underexposure on your film?

My back is toward the sun, and the image is underexposed by about one stop.

 

[BrianShaw]

See post 2...

 

[Pieter12]

No, it is not a back lit scene. The sun is directly from behind THE PHOTOGRAPHER!


My back is toward the sun, and the image is underexposed by about one stop.

Example?

 

[Vaughn]

If your back is to the sun, you can probably scratch the low light reflecting off the landscape as causing a higher light reading. (which is why I thought you were pointing towards the sun.)

I use a spot meter and have never noticed an issue. Although I imagine someone using color transparency film might notice minor changes more than I.

 

[Kino]

If the area being metered is substantially light/bright, and it encompasses the majority of the area being metered or the reflected light dominates the field being measured, it will average the scene to gray and underexpose the scene. Like shooting in a snow filled scene.

 

[Doremus Scudder]

If the area being metered is substantially light/bright, and it encompasses the majority of the area being metered or the reflected light dominates the field being measured, it will average the scene to gray and underexpose the scene. Like shooting in a snow filled scene.

This is likely your best answer. No appreciable shadows in the scene metered with an averaging meter designed to read "correctly" when there is a mix of lit and shadowed areas causes the meter to think the scene is brighter than it really is.

Just learn to recognize the conditions that cause this and use exposure compensation. Really, that's basic standard practice with averaging meters; you have to evaluate carefully the scene to determine if it is "average" (i.e. equal mix of light, shadow, tones) or predominantly brighter or darker than "average." That's why so many of us use spot meters.

BTW, an incident reading or even a grey card reading should give you a bench line to compare to.

Best,

Doremus

 

[foc]

If in doubt, use an incident reading.

With low direct sunshine from behind, you will get long shadows and this is not an average metering situation. (just like it's not sunny 16 lighting)

Personally, I love this type of light, especially if it comes at around 45 degree angle to the camera. I find it shows off great texture.

 

[wiltw]

Keep in mind that your meter averages together everything within its field of view, so if your primary subject is in light which is somewhat darker than 'the average of everthing it sees', it would be underexposed compared to 'the average'.

In most scenes 'the average' and the subject exposure are the same. In other scenes, like in the snow, 'the average' is seen by the meter brighter than usual, so your subject is underexposed because the meter saw the scene as very bright.

Metering features like 'center weighted' were an attempt to get the meter to ignore things around the primary subject (who is assumed to be at the center of the frame).
Meter advanced to 'evaluative' systems which made an attempt at 'smart guess' metering based upon certain characteristics, but even these best guesses can be fooled.
Then there is the 'spot' meter...and the problem is when the user points the spotmeter on a subject which is not 'average' in brightness...point a spotmeter at a black tux coat and you get overexposure, point a spotmeter at a bride's white wedding gown and you get underexposure...it is up to the user to pick an 'average brightness' target area in order for the spotmeter to give you a good exposure all the time, which is why photographers use 'gray cards'!