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Exposure

February 17, 2011

For this experiment:

OFF AiAF (Auto-focus)
OFF Red-eye
OFF AF-assist Beam

I then ran through it in two modes: P and Av (Variable Aperture). In both cases, the camera is mounted on a Gorilla Grip Tripod.  This picture is taken with my iPhone, and is for documentation only:

Settings:

Light-metering: Spot
Timer: 10 seconds
ISO 50
Custom White Balance:

This only worked with color images, unfortunately.  Not sure why this is, and need to work through this some more.  The black and white images shot at f-3.5 were all blurry and not worth showing here.  At f-5.6, though, they came out quite nicely.  Eric Rosenthal pointed out in class that as an industry standard, to minimize lens chromatic aberration, manufacturers deliberately optimize their settings for f-5.6, so the reason for choosing that stop.

The winners are:

At f-3.5, bracketed down 1/3 of a stop:

At f-5.6, bracketed down 1/3 of a stop:

I checked the grey cards in Photoshop, and with no exposure compensation, they have a value of roughly 145 for the B&W image, 145,145,145 for the color image shot at f-3.5, and 150,150,145 for the color image shot at f-5.6.

Not surprisingly, the readings were lower when stopped down, roughly 130-135 for all readings, and 1/3 of a stop up produced readings of 170.  I prefer 1/3-2/3 of a stop down, though, and I believe the histograms back this up.

Here are the histograms and camera data for all brackets and exposures:

P Setting:

Av Setting, at f-5.6:

I did not bother bracketing upwards in these cases as I felt that the camera tends to over-expose based on my previous tests.

I reshot this one because it was blurry, but seemed well-exposed:

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