Transcript PPT

Basic Digital Photography
Why Digital?
• The ability to easily preview pictures and delete any bad
shots, and know immediately if a particular photo needs
to be re-shot
• The costs of film are replaced with memory cards/sticks
that can be re-used again and again, with the larger
cards/sticks having a capacity of thousands of pictures
• Since pictures are saved on memory cards/sticks, you
can easily share pictures by copying off the photos, or
sharing the card/stick
• Decisions on effects like cropping, sepia tones or black
and white, can be easily made after the picture has
already been taken
• Internal View
Pixels
• A pixel is a contraction of the term picture
element. Digital images are made up of
small squares, just like a tile mosaic on
your kitchen or bathroom wall. Though a
digital photograph looks smooth and
continuous just like a regular photograph,
it's actually composed of millions of tiny
squares as shown below.
• Pixel are really just 1s and 0s – or on/off
Pixel cont.
Pixel Count
• The number of individual pixels that go
into making each image
• A million pixels is abbreviated to MP, so a
1MP camera has 1 million pixels and a
3MP camera has 3 million pixels
3MP
4MP
5MP
2048 x 1536
2272 x 1712
2592 x 1944
Print size at
320dpi
6.5" x 4.8"
7.1" x 5.4"
8.1" x 6.1"
Print size at
240dpi
8.5" x 6.4"
9.5" x 7.1"
10.8" x 8.1"
Largest Image
(typical)
Resolution
• Is the amount of detail the camera will be able to
capture.
• The more pixels in the camera’s receptor, the more detail
the camera will be able to capture and print out in larger
high-quality prints.
• Most newer entry level models start at about 13MP.
• Cameras with 5MP or higher will allow you to make clear
prints in larger sizes, and giving you the freedom to crop
an image later without significantly losing quality.
• Higher mega pixel cameras are a benefit because when
you go in and edit something, and blow it back up to
regular size, you lose some of the resolution.
Image Resolution
Maximum Print Size
less than 640X480
Wallet size only
640X480
absolute largest, 4X6
1024X768
4X6
1152X864
5X7
1600X1200
8X10
Aspect Ratio
• The aspect ratio of a camera is the ratio of
the length of the sides of the images
• For example, a traditional 35mm film
frame is approximately 36mm wide and
24mm HIGH. This has an aspect ratio of
36:24, which can equally well be
expressed as 3:2.
• However, video monitors typically use a
4:3 aspect ratio.
Digital Zoom vs Optical Zoom
• Optical zoom works just like a zoom lens
on a film camera. The lens changes focal
length and magnification as it is zoomed.
Image quality stays high throughout the
zoom range.
• Digital zoom simply crops the image to a
smaller size, then enlarges the cropped
portion to fill the frame again. Digital zoom
results in a significant loss of quality.
File Types
• JPEG, TIFF and RAW
• The size of the digital file corresponding to
the image which the camera produces
depends on the pixel count.
• The files are can be big and they can be
compressed quite a lot without a
significant drop in quality.
Compression Types
• A lossy compression method is one where
compressing data and then decompressing it
retrieves data that may well be different from the
original, but is close enough to be useful in
some way
• Lossless data compression is a class of data
compression algorithms that allows the exact
original data to be reconstructed from the
compressed data. Lossless compression is used
when it is important that the original and the
decompressed data be identical.
Joint Photo Experts Group
• JPEG is an algorithm designed to work
with continuous tone photographic
images) which takes image data and
compresses it in a lossy manner (this
means you do lose some information)
• The more you compress, the smaller the
file but the more information you lose
On the left, 10:1 JPEG
compression. On the Right 40:1
compression.
Uncompressed the image would
look virtually identical to the 10:1
JPEG on the left.
Tagged Image File Format
• There are also lossless ways of saving
files using TIFF
• These keep all the original information, but
at the cost of much bigger files
RAW
• Some cameras offer a third option, that of
saving the actual data generated by the
sensor in a proprietary format
• These files are compressed, but in a nonlossy manner. They are significantly
smaller than equivalent TIFF files, but
larger than JPEGs.
Display, Printing, DPI and PPI
• When you display a digital image on a
monitor, the only thing that determines the
size of the image is the pixel count and
aspect ratio
• PPI stands for "Pixels per inch" and is
almost exclusively used for printing, not
video display.
• DPI stands for "dots per inch" and is a
property of a printer, not a digital image
Memory
• Most cameras ship with memory included, either
built in or as a low-capacity memory card that
will store a handful of images at your camera’s
lowest resolution.
• Memory card capacity is measured in
megabytes (MB) or even gigabytes (GB).
• A 16 MB card is usually included with the
camera will hold only 6-8 full-resolution images
in a 4-MP camera.
• A 256 MB card will hold about 125 full-resolution
images.
• 512GB card will hold 100,000+ full-resolution
images.
Types of Memory
• Compact Flash (CF)
• Secure Digital (SD) - Very small.
They have a built in write protect
switch to prevent accidental
erasure and certain encryption
capabilities of little interest to
digital camera owners.
• Smart Media - Thinner than CF
cards, but lacking an on-card
memory controller.
• Memory Stick - Introduced by
Sony and used only by Sony
LCD Screen
• A colour LCD screen is a
standard feature used to
frame your shot, review
your photos and view
menu functions.
• Screens are usually 1 ½
to 2 ½ inches, measured
diagonally.
• Most cameras also
feature optical
viewfinders and are
handy in the sunlight
when LCD’s are
sometimes difficult to
view.
• LCD screens are a big
drain on your battery and
can be turned off to
conserve battery life.
The Point and Shoot Camera
Advantages of point and shoot
cameras:
First and foremost, it is the Size.
Weight. Most point and shoot cameras are very light weight.
You do not need extra bags, tripods or other accessories to
carry around. Fixed lens. All point and shoot cameras come
with fixed lenses. You don’t sweat in trying to change lenses.
Massive Depth of Field. In layman’s terms, it means that
point and shoot cameras typically cannot separate
foreground from background, bringing everything in focus
and making the entire scene look sharp. This could be both
good and bad.
Price. A point-and-shoot camera is always going to be
cheaper to purchase and maintain than a DSLR.
Example - NIKON D700 @ 85mm, ISO 250, 1/250, f/2.8
https://cdn.photographylife.com/wpcontent/uploads/2009/12/Malika-3-960x639.jpg
Disadvantages of point and shoot
cameras:
Quality. Due to the smaller size of the camera sensor.
Downside of a large depth of field. While a point and shoot gets your
entire scene nicely in focus, there is not much you can do to isolate your
subject from the background and make it look soft and blurry.
Adaptability. Point and shoot cameras are not upgradable. You cannot
change their lenses or mount external flashes
Limited control. Unlike DSLRs, point and shoot cameras give much less
control over the process of taking pictures.
Shooting in the dark. Point-and-shoot cameras do not have good
capabilities for night photography.
Inability to capture wide-angle shots. Most point and shoot cameras
have lenses that start at 30-35mm, which means that you cannot fit much of
the scene and would have to stand back to capture more.
Most point and shoot cameras are limited in how fast they can capture an
image. Point and shoots are not designed for sports and action
photography.
The DSLR Camera
Advantages of DSLR
Better image quality. A DSLR camera typically has a much bigger sensor
than a point and shoot camera.
Better sensitivity to light.
shutter and focus speeds. DSLRs can acquire focus very quickly and
take multiple shots per second.
You see what you shoot. A DSLR is constructed with reflex mirrors,
which means that you look through the lens, instead of a see-through hole
in the camera.
Flexible Controls.
Better investment. Generally, DSLR cameras hold their values much
better than point and shoots.
Ability to use different lenses.
Full control over depth of field. You are fully in charge of isolating
foreground from background or bring everything in focus through aperture
control of the lens.
Weather sealing.
Solid construction.
Example – https://cdn.photographylife.com/wpcontent/uploads/2009/12/Jade-Portrait.jpg
Disadvantages of DSLR
• High price tag.
• Weight and Size.
• Noise. Due to the nature of DSLRs and their construction, every
time the shutter opens and closes, there is a substantial amount of
noise that comes out of the camera. Some newer cameras now
have a special “Quiet” mode
Credit
• https://photographylife.com/dslr-vs-point-and-shoot-camera
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