Introduction to Digital Photography

Spring 2010Instructor, Francesca Hampton

Topics we’ll cover today

Pros and Cons What digital means Examples of digital possibilities Pixels and resolution Memory chips Memory cards Some currently popular digital cameras Batteries and common accessories Other ways of “going digital” Introduction to our course web page

A caveatLike many amateur photographers, I am self-taught. We may occasionally have questions we will have to find answers for together, but finding where to look for answers is a key part of learning the basics.If you are curious to see my work, you can visit my online galleries at

Photography by Francesca Hampton (Picasa gallery)Or Cruzio gallery (older work)

Pros and Cons of “going digital”

Pros See the shot now No more film costs! Easier to share & store Web & email ready Simple to retouch Creativity unlimited Easy to make your own

cards, flyers and calendars.

Cons Initial expense Computer and

printer (usually) required

Some technical knowledge needed

What makes a digital camera different?

A digital camera captures light information onto a computer chip which converts it to a mathematical formula. The chip may be a Coupled Device (CCD) or Complementary Metal Oxide Semiconductor (CMOS).

In regular cameras light would go directly onto film. In digital cameras the processed light information is written onto “Memory cards” which can be erased and reused once the images have been uploaded to a computer, e.g. you can take unlimited pictures for free! No more film!

A peek inside

Light is focused on this sensor by the lens

Light hitting a CMOS chip is similar

Light is measured by each small square in the sensor and processed into a mathematical pattern of ones and zeros

that allow for the expression of millions of colors.

CCD or CMOS Chip Size

CMOS is less expensive to produce but not as sensitive as a CCD

Larger chips create image files with more information measured in “dots per inch or dpi.

Up to a point, this means you can produce physically larger images without pixalization artifacts

CMOS

What the heck is a pixalization artifact?When digital information is recorded inaccurately,

some pixels develop errors and show the wrong color. This can result in a grainy or rainbow effect most visible in clear areas such as the sky. “Anti-Noise software can reduce this effect. The best antidote is to take a picture at a resolution large enough for the print size you want and find the most accurate light setting before shooting.

Let’s start with another question. What is a digital image?

A digital image is created by thousands of tiny squares of digital information, called picture elements or “pixels.”

An image size is described as dots (pixels) wide by dots high. Typical sizes are 1280 x 960, or 2560 x 1920. Even 5184 x 3456 is common this year.

Each pixel is a single color expressed as a digital pattern of 8,16, 24 or 32 ones and zeroes.

Digital Image Characteristics

Even “24-bit” color allows for 16 million + shades.

From a distance, pixels blend to look like a picture.

Up close each pixel becomes visible. More total pixels allow more detail in an image. However, more pixels also mean more

computer memory space to store the image.

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Normal View

A section of the enlarged image

Image enlarged a lot!Notice that each pixel square expresses a single color.

Digital images are recorded on memory cards

There are several types of memory cards. Your camera will use only one type. Find out what it is.

Memory cards can be removed and inserted into card readers to upload them into computers or directly to printers. Your camera itself can serve as a card reader.

Memory cards are erasable and reusable and hold literally thousands of images -up to 16GB!

Image Size versus print size

A 1 Megapixel camera in a cell phone can give good results online viewing since computer screen resolution is only 72dpi, dots per inch - but it is not much good for prints beyond 3X5 inches.

A 6 Megapixel camera can produce a good 13 x 19 print or even larger depending on the subject.

These days, even inexpensive cameras routinely offer 10 or more MB and prints of 40X60” or more.

Be aware that there is a trade off in the amount of “noise” in high MB cameras. The best image result may actually come from a medium high MB camera with a high quality lens and processor.

So many choices!We will look more closely at digital camera features next class but

here is a sampling of some currently popular models online today.

Canon Digital Rebel XS $579

Nikon D90 $750

$950 w/lense kit

Kodak easyshare $79

Panasonic Lumix $140

All the other stuffCommon digital accessories

Hmm - more stuff to buy!• Batteries/ re-charger• Strobe lights?•Lens cleaner?•Camera bag?•Cables (come with camera)•Tripod?•Card reader? But remember the trade off - no film & very low print costs!

Still prefer film but want the advantages of digitalization?

1. Go right ahead, keep using your film camera but order a CD (compact disk) when you have the film developed. Although this will cost a little extra, the digital file on a CD is just as usable as the one from a digital camera if it is scanned at high resolution.

2. For old prints or 35 mm slides, buy a print scanner or a “film” (slide) scanner and scan your own photos into digital format on your own computer - or, again, to to a professional service. (Bay Photo offers this locally).

Ready to start the adventure?

Let’s see what cameras we have in the class today and turn them on!