Photography

Subject:
metering

Darrin Hill

metering.. the final frontier and subject to lots of arguments..

In 1888 (or so) george eastman sent people all around the world to measure how much objects reflect light... and it was discovered that almost everything reflects about 18% of the light back.. and thus was invented the 18% grey card..

so the question is... when your camera is trying to figure all the settings, what color does it see when it tries to set the controls for exposure? well... it's actually grey, cause a camera only sees various degrees of grey,...

Look at the left... really literally left... see the latest sighting of the woodcentral cap? Usually when a camera sets the controls, it takes EVERYTHING into consideration... sky, grass, cap, white part of rock, shadows under mountain.. etc... THe issue is that your eye sees a much greater range of contrast (difference between black and white) than a camera does, and the values of blacks and white, when in an extreme (or normal ) situation, sometimes will throw off the computer...

an example is .. the sky.. it's about 5 stops brighter than your subject... and a camera usually has a range of about 5 fstops..

and lets get technical... ever hear of ansel adams? he was able to pre-visualize how a scene was supposed to look even before he pushed a button... And a good part of his work was done in camera, but most was done in the darkroom. We'll ignore the darkroom thing and continue. His big deal was he was able to expose his negative for the shadows of an image, and develop for the highlights.. He founded what is called the zone system, where an image will hold about 10 varying shades of grey.. zones 0 I II III IV V VI VII VIII XI and X. Zone V is our middle tone (cause it's in the middle ), zone 0 is black as black can be, and zone X is white as snow. Through in-camera manipulation and darkroom development, he was able to stretch the contrast range of an image, which is why his images sell for gobs of $.

The reason we need to know this is think of your hand... and your fingers and thumb...your bad finger (middle finger ) is your middle tone, zone V. Neither film nor digital, without manipulation, can handle contrast that is greater than 3 stops that are greater or less than your zone V. thus your fingers on the left represent dark, and your pointy finger is white.. Basically if your meter says your exposure is f8, anything in your image that is less than f2.8 or greater than 22 will not record.

in a uber complicated nutshell, if you have a bowl your photographing... using a grey background, and the bowl is made of black, white and grey wood, the grey will show the grain pattern, but the black will be too underexposed, and the white will be too over exposed to show detail. Nowadays we take 3 different images with 3 different exposures and photoshop them together, so that your dark and white shows details and everything else does too.. and the image will look more like what your eye sees..

what would mess your exposure way up is when you have a white or black background... The camera will take that into consideration and it would throw your exposure way off...

what will help is an 18% grey card. If you place this card where your bowl is, meter off the card, your exposure will be perfect.. we're not using any flash at all.. just available light.

two hints.. grass is a perfect 18% grey (yes, it's green, i know)... but if your subject is standing on grass, aim your camera there and use that for your exposure. Also your hand is almost a perfect 18%... but its usually around 1/2 a stop over... so just meter off your hand and close down 1/2 a stop.

anyone want to improve on this feel free... i know what im trying to say but it dont come out right...

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