Polaroid Cameras I User Manual

Cameras I

Basic operation and features

Why Digital?

With digital photography you can do things that you can not do with film:

• Snap anytime- there is no cost until you print!

• There is no such thing as a roll of film. Snap 2, 10 or 100 photos at a time.

• Use the camera’s automatic mode – a computer helps take a great picture.

• Review the picture immediately after you snap it. Delete and re-snap if required.

• Print what you want, when you want.

• Save money at the photo counter – only print what you like.

• Edit your photos on the computer – Crop, remove red-eye, improve contrast and

more.

• Combine photos for interesting effects. Add people or take them out!

• Make your own greeting cards, newsletters, brochures, business cards, all in full

color.

2004 was a milestone year in digital photography. In 2000, digital camera sales
worldwide in dollars exceeded film camera sales. In 2004, digital still cameras overtook
film camera sales in numbers, with over 75 million units sold worldwide, as opposed to
approximately 50 million film cameras sold. The number of film cameras sold is
declining in double digit percentages.

Costs of digital camera have dropped to the point where they are competitive with film
cameras.

Units, Millions

Digital v. Film: Camera Sales

90
80
70
60
50
40
30
20
10

0

1999 2000 2001 2002 2003 2004

Digi t al Wor l dwi de
Dig it a l US
Fil m W or l dwi de
Fil m US

Digi t al Wor l dwi de
Dig it a l US
Film Worldwide
Fil m US

5.5 11 18.5 30.5 50 78
2 4.3 6.5 11.5 17 23

67 71 66 63 57 49

16.820.619191613

Year

We are in the midst of a technological revolution that rivals the inventions of the
automobile, the telephone, the television and the computer. Only this revolution is
happening much faster. Over 23 million digital cameras were sold in the US in 2004.

Why now?

Advances in computer processing coupled with drastic reductions in the cost of computer
memory have converged to supply low cost cameras that can produce quality images.
When you hold a digital camera in your hand, you hold a hundred times the processing
power and memory of the flight computers on the Space Shuttle!

The digital camera allows the amateur to take better pictures than with film. Why? The
computer in the camera makes many adjustments prior to the shot. It not only adjusts the
focus, but plans the exposure, contrast, lighting and the flash and adjusts the color
balance for the ambient light. A film photographer would change film types or add filters
to do the same thing; but the camera does it all in less than a second.

Elements of a digital camera

A digital camera is a lot different than a film camera. Until the advent of auto-focus in the
1980s, film cameras had very little in terms of electronics. A shutter release activated a
spring loaded shutter and the film was briefly exposed to the image through the lens. The

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shutter button and lens are virtually the only parts of the camera that remain in digital
cameras.

The film has been replaced with a light sensitive chip, called a Charge Coupled Device
(CCD). This chip is an array of millions elements that are sensitive to light. When light
hits an element in the CCD array, a electrical charge is accumulated at a rate determined
by the amount of light striking it. This charge is then measured by an analog to digital
converter that converts the voltage to a digital value that can be stored in memory. The
raw image derived from the CCD is too big to store. The camera contains a specialized
chip know as the compression engine, which takes the raw image and compresses it to a
size that can be stored on the memory card. This compression reduces the overall storage
requirement by a factor of 3 to 16.

This is a block diagram of a camera from the Texas Instrument web site (www.ti.com
They want designers to use their integrated circuits, so they supply much of the design for
the camera.

).

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The block diagram shows a fast microprocessor, memory, a color display and buttons for
a user interface; with a power supply for rechargeable battery operation. That would be a
good description for a laptop computer. Add the lens and the CCD module and you have
a camera!

All of this processing power means that the camera can make many calculations and
decisions while you take the picture.

Before the shot:

• Display options on the screen and allow the user to change them with the buttons

• Display the viewed image on the LCD screen

• Focus the camera

• Determine exposure time and whether to fire the flash

• Charge the flash, if needed

• Determine the color balance to correct for lighting

During the shot

• Discharge the CCD

• Expose the CCD to the image for the time required

• Fire the flash

• Stop charging the CCD after the proper exposure is made

After the shot:

• Measure the charge on all the elements of the CCD (all 4 million in a 4 megapixel

camera)

• Convert the voltage on each of the CCD elements to a number

• Store the raw image in memory

• Read the raw image out of memory and compress it using a JPEG algorithm

• Store the compressed image on the memory card

• Display the photo briefly on the LCD panel

• Calculate memory remaining and display the number of shots remaining.

Sound like a lot of computation. It is! And that’s just part of it, since it must do all that
three times to do color!

The focus, exposure and color balance calculations are the principle reason that most
people take better photos with a digital camera than with film. Although modern film
cameras do an admirable job with focus and exposure control, no film camera can do
color compensation. With film you must use a different film for outdoor and indoor shots,
or put a filter over the lens.

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What the heck is a megapixel?

Mega is a prefix that means million. A pixel refers to the element on the CCD that
captures light. Thus a 4 megapixel camera has approximately 4 million sensing elements
on its CCD.

The megapixels a camera has nothing to do with the size of the image, but has everything
to do with resolution. You can get a print of any size with any camera, but the image
quality will be better the higher the resolution.

Here is an extreme example:

1600x1200 pixels 80x60 pixels

The following is a guide to the maximum size of pictures from common cameras:

2-megapixel - 1600x1200

3-megapixel - 2048x1536
4-megapixel - 2272 x 1704
5-megapixel - 2568 x 1928
6-megapixel - 3072 x 2000
8-megapixel - 3264 x 2448

11-megapixel - 4064 x 2704

The higher the number of pixels, the greater the need for storage. An image stored in a 4
megapixel camera takes twice the memory space as does that from a 2 megapixel camera.

Cameras can take pictures in lower resolution. For example, a 4 megapixel camera can be
set to take pictures in 2 megapixel or 1 megapixel mode. The only advantage to this is the
reduction in required storage space; more pictures will be stored on the memory card. For
example, a four megapixel camera will take pictures at 2272 x 1704 and also 1600x1200
as a 2-megapixel camera would. When would you want to cut down the resolution? If
you know that you are producing photos for the web or eBay or any purpose where
resolution is not needed, go ahead and use the lower resolution. Otherwise, shoot at the
highest resolution of your camera.

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Remember: while you can always decrease resolution using editing software, you can
never increase it.

A rough rule of thumb is that the memory required per picture is one half of the
megapixel rating of the camera. Thus a 4 megapixel camera will require 2 Mbytes of
storage per picture.

Professionals put the resolution required for parity with film at about 250-300 pixels per
inch. Thus for an 8x10” print, a 6 megapixel camera would be required.

This rule is somewhat subjective. Most find that 8x10s are satisfactorily produced with 4,
3 or even 2 megapixel cameras, although most notice some degradation and tiling at 2
megapixels and below.

In the following example, I have reproduced several images on the page in resolutions
that represent the resolution produced by cameras printing an 8x10” print in 6, 4, 2 and 1
megapixel resolution.

300 pixels per inch, same as a 6 megapixel camera printing

an 8x10

160 pixels per inch, same as a 2 megapixel camera printing

an 8x10

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225 pixels per inch, same as a 4 megapixel camera

printing an 8x10

100 pixels per inch, same as a 1 megapixel camera

printing an 8x10

Can you see the difference? You can probably tell that the 1 megapixel camera is not as
good for 8x10s. It is still adequate for email or eBay work but not acceptable for taking
quality pictures that will be enlarged. Is 2 megapixels enough? That is up to you: it may
be, if a camera has other features you like. Certainly by the time you get to 3, 4 or 5
megapixels you are going to get quality prints (in my opinion). If you are a person who
will accept nothing but the absolute best quality, spring for a 6 megapixel or greater
camera. You will be pleased with the quality you achieve.

One more thing to consider when considering what megapixel camera to buy: as the
megapixels go up, so do the features found in the camera. Generally the more expensive
the camera, the higher the megapixels, the better the lens and feature set in that camera.

How will you be using the camera?

Low resolution applications:

Posting photos on the internet or viewing them on the computer
Sending photographs by email

Medium Resolution applications

Printing photos on standard paper or making small (4x6” or 5x7”) at the photo kiosk

High resolution applications.

Printing enlargements, including 8x10s
Professional graphics

Zoom: Optical required, Digital only is not acceptable

An optical zoom uses the lens system in the camera to “zoom in” on the subject. The
subject is larger with no loss of resolution or image quality. A digital zoom works by
increasing the subject size digitally. A section of the image is magnified to the full
resolution of the camera. For example: a 3x digital zoom takes 1/9
converts it to full frame. Since no more megapixels have been added to the CCD,
resolution is lost. Using a 2 megapixel camera with at 3x digital zoom is the same as
using a 0.3 megapixel camera. The image quality will be poor. You will notice a grainy
and blocky picture, as illustrated above. This is no different than taking a un-zoomed
picture into a editing programming and cropping and enlarging it three times. Low cost
cameras often tout their digital zoom without an optical zoom. DO NOT BUY A
CAMERA WITH ONLY A DIGITAL ZOOM.

Most cameras now have an optical zoom. 3x is very common, although some now offer 7
to 10x zooms. For most applications 3x is a good compromise and will work great.
Generally a 3x zoom will be the equivalent of a 35-105 mm lens on a 35mm camera,
which is slightly wide angle to telephoto. It is not a strong enough zoom to get very
distant objects. If your hobby is bird-watching or sports photography, consider a 7 to 10x
zoom.

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of the image and

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