Sigma SD15 User Manual

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HISTOGRAM
The histogram is a graph depicting the distribution of brightness values in
the image for each of the three color channels (Red, Green, and Blue) (The
histogram displayed in the Quick Preview is the distribution of tones in the
image). The horizontal axis shows the brightness level, with darker pixels
towards the left side and brighter pixels toward the right. The vertical axis
shows the proportion of pixels at each level of brightness.
By examining the histogram of the full image, you can gauge the over-all
exposure of that image. You can also use the histogram to determine if
zoomed-in sections of an image are over or under exposed.
This histogram shows that the higher pixel
values are never used in the image,
indicating that the image is underexposed,
and therefore will appear dark. In general,
when the histogram is higher on the left side,
the image is mostly composed of dark pixels,
causing it to appear dark—either because
the image is underexposed or because it is a
dark scene such as night shot or sunset.
This histogram shows a fairly even
distribution of pixel values, indicating that the
image is well exposed, with good contrast.
However, the histogram distribution of a well
exposed image will vary greatly depending
on the subject.
This histogram shows that many of the pixel
values are at their brightness limit, indicating
that some areas of the image may be blown
out. In general, when the histogram runs off
the right side, the image will have many white
pixels—either because the image is
overexposed or because it is a bright scene
such as the beach or snow.

Sigma SD15 Specifications

General

Camera Type	Interchangeable Lens SLR Type Digital Camera
Image Sensor Size	13.8 x 20.7mm
Lenses Used	Sigma SA Mount Lenses
Picture Angle	Equivalent to 1.7x the focal length of a lens when used on a 35mm SLR camera.
Lens Mount	SA mount
Imaging Element Type	FOVEON® X3™ (CMOS)
Color Photo Detectors	14.06 Million (2652 Columns x 1768 Rows x 3 Layers)
Image Recording Format	Lossless compression RAW Data (12bit), JEPG
White Balance	8 Type (Auto, Sunlight, Shade, Overcast, Incandescent, Fluorescent, Flash, Custom white balance)
Viewfinder Type	Pentaprism SLR Viewfinder
Viewfinder Frame Coverage	98％ horizontal, 98％ vertical
Viewfinder Magnification	0.9x (50mm F1.4 at infinity)
Eyepoint	18mm
Diopter Adjustment Range	-3dpt to +1.5dpt
Auto Focus Type	TTL phase difference detection system
AF Operating Range	EV 0 to 18 (ISO100)
Focus Mode	Single AF, Continuous AF (AF Predict function), MF
Metering Systems	Evaluative Metering, Center-Weighted Average Metering, Center Area Metering, Spot metering
Metering Range	EV 1 to 20 (with 50mm F1.4 at ISO100)
Exposure Modes	(P) Program AE、(A) Aperture Priority AE、 (S) Shutter Speed Priority AE、(M) Manual
ISO Sensivity	ISO (50), 100, 200, 400, 800, 1600, (3200) *( )Extended Mode
Exposure Compensation	±3EV (in 1/3steps)
AE Lock	Push button type
Auto Bracketing	Three or five frames (in 1/3steps, Appropriate Exposure – Under Exposure – Over Exposure)
Shutter Type	Vertical-travel metal focal plane shutter, electronically controlled through entire speed range
Storage Media	SD Card / Compatible with SDHC, Multi Media Card
Aspect Ratio	3：2
Resolution	HI：2640 x 1760 MED：1872 x 1248, LOW：1312 x 880
Interfaces	USB 2.0, Video Out (NTSC／PAL)