FYS 100Creative Discovery in Digital Art Forms

Spring 2007

Burg

Digital Photography Assignment

Image Quality and Image Size •Image quality is a matter of file and compression type (if there is compression).•File type is normally JPG or TIFF. TIFF files can be compressed or uncompressed. Some cameras call this spec “image quality.”•Image size is a matter of resolution (if you’re talking about the size on the computer screen) or resolution/ppi (if you’re talking about printed size).•Know the choices you have of resolution and file type for your camera. •Resolution is the number of pixels in the horizontal and vertical directions. Some cameras call this “image size” in their specs.•Your choice of resolution and file type affects the file size and how many pictures you can take on your memory card.

Nikon CoolPix 995

Image Quality

Nikon CoolPix 995 Image Size

File Size

• How many 2048 x 1536 pixel images can you fit on a 64 MB memory card? – MB standards for megabyte (220 bytes)– We think of a megabyte as about 1,000,000

bytes, but it’s actually more. It’s 220 = 1,048,576.

– RGB color is used. This means that one byte is used for each color channel for each pixel.

Let’s do the arithmetic…

2048 x 1536 = 3,145,728 pixels3,145,728 pixels * 3 bytes/pixel = 9,437,184

bytes9,437,184 bytes 9.4 MB64 9.4 = 6

Six 2048 x 1536 uncompressed TIFF pictures can be stored on a 64 MB memory card

Lossy vs. Lossless Compression

• Lossy compression removes some detail, but it’s probably detail you wouldn’t notice anyway.

• JPEG is lossy (but still good quality).

• The compression type used with TIFF is lossless (but you don’t have to compress a TIFF file).

Aperture, Focal Length, and F-Stop

• Aperture is the opening in the lens to light light in.

• F-stop is the ratio of the focal length of the lens to the diameter of the opening of the aperture. A smaller f-stop number means a wider aperture.

• Wider apertures let in more light. • Wider apertures (i.e., smaller f-stop numbers)

also create a shallower depth of field.• A shallow depth of field makes objects in the

foreground stand out while the background is blurry.

f2 f2.8 f4

f5.6 f8 f11

F-stops

Shallow depth of field

From Digital Photography by Katrin Eismann, Seán Duggan, and Tim Grey,PeachPit Press

Deep focus

Point-and-Shoot and “Prosumer” Cameras

• Point-and-shoot automatically adjust the f-stop, shutter speed, and focus as you take a picture.

• Some allow you have a few options for image quality and or/or size, but perhaps not. You might be able to take only JPEG images in a fixed resolution.

• “Prosumer” cameras are somewhere between professional and consumer level. Nikon CoolPix 995 is a prosumer camera. (You can borrow mine.)

SLR Cameras

• SLR refers to single lens reflex. This is a professional grade camera. You look straight through the lens.

• Professional digital SLRs use an imaging sensor that’s the same size as the 35mm film they replace, so the specs of lens size and focal length match what you might be used to in analog cameras.

• SLRs often have interchangeable lenses.

The CS Department has an SLR Camera, a NIKON D100

• SLR (single-lens reflex) The advantage of SLR is that when you look through the viewfinder, you are seeing exactly the image that you will take.  This makes it possible for you to use manual focusing in a very accurate way.

• We bought two lenses for the camera.  (You often have to buy the lenses of SLR cameras separately.) – Nikon AF Nikkor – Nikon AF Micro Nikkor 60mm f/2.8D (for close-ups)

• CCD (charge-coupled device) is 23.7 x 15.6 mm/0.9" x 0.6" • advertised as 6.1 million "effective" pixels  (Multiply 3008 x 2000

and you get approximately this value. Manufacturers always advertise their maximum pixel size ("megapixels") to their advantage.)

NIKON D100• image size (resolution): 

– 3008 X 2000 pixels, 2240 X 1488 pixels, or 1504 X 1000 pixels

• six image qualities/file types: – NEF raw uncompressed (12 bits per pixel) – NEF raw compressed – TIFF-RGB (uncompressed) – JPEG Fine (lossy compression at a ratio of 4:1) – JPEG Normal (lossy compression at a ratio of 8:1) – JPEG Basic (lossy compression at a ratio of 16:1)

(See page 43 of the camera manual for the relationship between image size in terms of pixels, image quality, and image size in terms of number of bytes required for storage.)

NIKON D100• 3D matrix metering as its method to determine correct

exposure (See http://en.wikipedia.org/wiki/Matrix_metering.)• built-in Speedlight • single frame, continuous, or self-timer shooting modes • "film" sensitivity levels between values roughly equivalent to

between ISO 200 and 1600 in steps equivalent to 1/3 EV.  Higher values of HI-1 (ISO 3200) and HI-2 (ISO 6400) also possible.

• manual settings can be made for aperture, sensitivity, shutter speed, focus, single-shot vs. continuous mode, etc.

• storage medium – Nikon, SanDisk, LexarMedia, or IBM CompactFlash cards

• photos transferable to computer through USB cable or CompactFlash Card adapter

NIKON D100 SetUp

NIKON D100 SetUp

NIKON D100 SetUp