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GSFC Photography ClubIntroduction to Digital Photography Class
Session 2 – Camera Mechanics
Scott Hull2/6/2012
Agenda
Terms Exposure Review Camera Types Camera Parts Memory Cards Camera Settings Shooting Modes and Scene Modes Lenses Filters Flash Gadgets
Terms
ISO (ISO = ASA) (adjustable) The sensitivity of the CCD sensor chip
Aperture (adjustable) The amount of the lens diameter that you use
White Balance (adjustable) The color correction for the light you are in
Optical vs. Digital Zoom Optical zoom is when the lens moves to expand or
contract the image Digital zoom is a marketing tool – basically just cropping
Live View The ability to view the image on the display while you
compose the shot
Stops
A whole ‘stop’ is a change in the amount of light by half or double 1/250 sec 1/125 sec 1/60 sec
400 ISO 200 ISO 100 ISO Aperture numbers change by a factor of
1.4 Square root of 2, since double the light is 2x
area Area of a circle is π r2 f/4 f/2.8 f/2
Most cameras also show partial stops
Exposure ReviewSunny 16 Rule
On a sunny day, at f/16, the shutter speed is 1/ISO
Stop Action Tripod Zone 11/21/41/81/151/301/601/1251/2501/5001/10001/20001/4000
ISO 100
f /22
f /11
f/ 16
f /4
f /5.6
f/ 8
f /2
f/ 2.8
f/ 1.4
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Exposure ReviewSunny 16 Rule
On a sunny day, at f/16, the shutter speed is 1/ISOThese ISOs are one stop apart.
Stop Action Tripod Zone 11/21/41/81/151/301/601/1251/2501/5001/10001/20001/4000
ISO 50ISO 100ISO 200ISO 400ISO 800ISO 1600ISO 3200ISO 6400
f /22
f /11
f/ 16
f /4
f /5.6
f/ 8
f /2
f/ 2.8
f/ 1.4
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Exposure ReviewSunny 16 Rule – in the shade (-2 stops)
At f/16, the shutter speed is 1/ISO + 2 stops1/100 sec + 2 stops more light is 1/25 sec
Stop Action Tripod Zone 11/21/41/81/151/301/601/1251/2501/5001/10001/20001/4000
ISO 50ISO 100ISO 200ISO 400ISO 800ISO 1600ISO 3200ISO 6400
f /22
f /11
f/ 16
f /4
f /5.6
f/ 8
f /2
f/ 2.8
f/ 1.4
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Exposure ReviewSunny 16 Rule – indoors (-4 stops)
At f/16, the shutter speed is 1/ISO + 4 stops1/100 sec + 4 stops more light is 1/6 sec
Stop Action Tripod Zone 11/21/41/81/151/301/601/1251/2501/5001/10001/20001/4000
ISO 50ISO 100ISO 200ISO 400ISO 800ISO 1600ISO 3200ISO 6400
f /22
f /11
f/ 16
f /4
f /5.6
f/ 8
f /2
f/ 2.8
f/ 1.4
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Camera Types
“Pocket” Camera
“Point and Shoot”
DSLRDigital SingleLens Reflex
“Bridge” Camera
Brands
Which is better, Canon or Nikon? My answer: Olympus
Differences can be subtle “Feel” – try several, and you’ll know Layout/ operations tends to follow a pattern New innovations in one vs. another Performance vs. image quality
Photographers tend to develop brand loyalty Lenses are expensive Easier to shoot in the ‘language’ you know Choose well, young shutterbug
Differences Between Camera Types(in a very general sense)
Point and Shoots + phones
Bridge Cameras DSLRs
Small – shirt pocket Medium – purse Large – carry or camera bag
Snapshots Good snapshots Documentation to artistry
Very weak flash (~10’) Stronger flash (~20’) Internal (~20’) + external
View the display only Electronic viewfinder Look through the lens
Short range zoom Short to very long zoom
Interchangeable lenses
Very small sensor chip Small sensor chip Medium to 35mm frame
Auto focus only Manual focus difficult
Manual or autofocus
Very lightweight Noticeable weight Noticeable to heavy weight
Images OK for 5x7 prints
Images OK for 8x10 prints
Images OK for BIG prints
Very inexpensive Reasonably priced Can get very expensive
Often keep it with you Grab and go Requires preparation
Camera Parts
All digital cameras have: Lens Shutter Shutter release Sensor Computer Display screen Battery Memory card(s)
Most also have: Viewfinder Built-in flash ¼ - 20 tripod mount
Some Have: Hot shoe Mirror / prism Grip Selection dial(s) Beam splitter
What’s inside a DSLR?
Sensors(size does matter)
• Blue box is 35 mm film frame
• The difference (white area) is the crop factor
Pixel Size determines light gathering ability
Camera Pixels
(MP)
Sensor Size (mm)
Sensor Size (pixels)
Pixel Size (µm)
Crop Factor
Nikon D40 6.0 23.7 x 15.5
3008 x 2000
7.9 1.5X
Nikon D200
10.0 23.6 x 15.8
3872 x 2592
6.1 1.5X
Nikon D90 12.3 23.6 x 15.8
4288 x 2848
5.5 1.5X
Canon 450D
12.2 22.2 x 14.8
4272 x 2848
5.2 1.6X
Canon Rebel T2i
18.0 22.3 x 14.9
5184 x 3456
4.3 1.6X
Canon 60D
18.0 22.3 x 14.9
5184 x 3456
4.3 1.6X
Olympus E-5
12.3 17.3 x 13.0
4032 x 3024
4.3 2X
Canon A95
5.0 7.14 x 5.36
2592 x 1944
2.8 -----
Canon PowerShot SX150 IS
14.1 6.17 x 4.55
4320 x 3240
1.4 -----
Smaller pixels mean less light, and more noise, especially in low light
Crop Factor
Reported relative to 35 mm film Same focal length lens that was used
on film camera now focuses onto a smaller sensor
The sensor image area becomes expanded when viewing, so it is effectively magnified
Because of this, a 100 mm lens on a Canon APS-C camera gives the same magnification image as a 160 mm lens would on 35 mm film
Most have two types of memory Internal – holds the picture right after you shoot Removable cards– for downloading to a computer
Card formats Limited by the camera Compact Flash – bigger, faster, often cheaper Secure Digital – SD, mini SD, micro SD, SDHC,
SDXC Memory Stick, xD, Smart Media are far less
common Make sure you don’t over-buy
Memory
Memory Card Speed
CF usually faster than SD SD Classes
Snapshots: Class 4 Enthusiast: Class 6 Professional: Class 10 Write speed slower than read speed
CF “X” Ratings Buy what you can afford Capacity vs. speed▪ Video▪ Fast subject▪ RAW vs. JPEG
Camera Settings
Exposure Modes Shooting Modes Scene Modes Focus Modes Metering/ Exposure Compensation File Type/ Image Quality White Balance Playback A whole book full of others – read that book!
(the User’s Manual)
Checklist
Olympus E-5 Checklist
Mode Prog Aper Shut Man Bulb My 1 My 2 My 3 Card CF SD
Exp. Comp. -5 -4 -3 -2 -1 -0.7 -0.3 0 +0.3 +0.7 +1 +2 +3 +4 +5
HDR No +/- 1 +/- 2 Noise Red. On Off File Format JPEG RAW Both
White Balance Auto Daylight Shadows Cloudy Tungsten Fluor. Flash
IS Off Auto Vert Horiz ISO Auto 100 200 400 800 1600 3200 6400
Focus Manual S-AF C-AF Manual S-AF + Manual Center Auto Off-center
Drive Single High Low 12 Sec 2 Sec IR IR 2sec Face Detect On Off
Flash Auto Red Eye Fill Off Long Red Eye Long Full 1/4 1/16 1/64
Exposure Modes Auto
Camera selects everything: aperture, shutter speed, focus, ISO, flash - all of it, with no overrides
Usually works, often doesn’t Program
Camera picks aperture & shutter speed; focus can be overridden Aperture Priority
User picks the aperture, camera picks the shutter speed to match Often the preferred go-to mode for experienced photographers
Shutter Priority User picks the shutter speed, camera picks the aperture to match
Manual User gets to/ has to pick all settings
Shooting Modes
Single shot Self-timer Burst Short delay Remote control Bulb Bracketing for HDR
Scene Modes
Portrait Landscape Night
Scene Night
Portrait Sports Indoor Candle
Self Portrait Sunset Fireworks Food Documents Beach/
Snow Underwater
(4 options)
Snow Close-up Museum Backlight Panorama Probably
many more…
A Few Common Scene Modes Sports
Increases ISO, for faster shutter speed Landscape
Chooses narrower aperture, for longer depth of field Portrait
Chooses wider aperture, for short depth of field Night Portrait
Long exposure for background, plus flash for faces Fireworks
VERY long exposure (seconds) – must use a tripod Beach/Snow
Compensates for bright reflections by increasing exposure Night Scene
Increases ISO, for greater light collection, no flash
Focus Modes
Autofocus on most new cameras is pretty darned good Still not always perfectly crisp Doesn’t work for all situations
Very dependent on having high contrast areas and lots of light
Focus point can usually be defined on DSLRs Might still need to tweak the ‘sweet spot’ Single vs. continuous autofocus Manual focus on point and shoot and bridge
cameras is difficult, if possible
Metering
Average Original film approach, not used much anymore
Spot ~1-5% of the field Location is usually definable, often in the center
Center-weighted average Central portion represents most of the input
Multi-zone metering (aka Matrix, ESP, others) Most commonly used default mode Mysterious algorithms consider many factors
including focus point, light distribution, etc. Use exposure compensation (+/-) to make
small adjustments
Files/ Image Quality
RAW vs. JPEG RAW is all of the data, straight from the sensor▪ Largest files, most flexibility later, and highest resolution
JPEG is processed and compressed before saving▪ Losses occur each time it is saved▪ Usually several levels of compression available
Why not just maximize everything with RAW? E-5 Example (12.3 MP camera)▪ RAW file: 12.4 MB, High quality JPEG: 5.3 MB▪ Little discernible loss in image quality▪ In fact, unprocessed RAW looks noisier at high magnification
Memory cards are big, but not infinite capacity RAW is also not as portable between viewers
RAW vs. JPEG
RAW: 12.4 MB JPEG: 5.3 MB
Olympus E-5; 12.3 MP camera(MD Renaissance Festival, 2011)
White Balance
Colors change based on the source of the light Light brown shirt in incandescent light can look green in
fluorescent light Even sunlight vs. shade makes a difference
Image is interpreted differently based on settings Auto white balance is pretty good ~98% of the time Check your display frequently, and change the WB
if necessary RAW images are not corrected, so you can change
it later if it was off Can also be set WB manually for unusual situations
Lenses
Built-in vs. interchangeable Depends on the camera type
Fixed vs. zoom Fixed is typically lighter and higher image quality Zoom is more flexible
Cheap vs. expensive More expensive lenses have more elements, better
coatings, wider apertures, heavier weight Macro capability
Highly detailed close-up images Teleconverters
Goes between camera and lens to produce 1.4, 1.6, or even 2.0 x the focal length
Zoom Lens Cautions
A ‘wobble’ of only 0.03° will cause the image to move by 1/8” at 20 feet With a 50 mm lens, you may not see that With a 400 mm lens, it is 8 times bigger, and very noticeable
Zoom lenses are also usually unbalanced when hand held More likely to get that 0.03° - or more
They also tend to have smaller apertures, so longer exposure times
Tripods help, but faster shutter speeds are more practical Tripod pointing is awkward and slow Usually means higher ISO, though more noise
Thus, the driver for more expensive, “faster” zoom lenses
Macro
Traditionally, image on negative larger than life
Today, 4x6 print larger than life Options
Macro lens▪ Many lenses have macro capability built-in
Extension tubes▪ Moves the lens further from the sensor
Add-on adapters – cheap and poor image quality Reversing adapters
Focus and depth of field are very difficult Lighting can be a real challenge
Short working distance – can be less than an inch!
Image Stabilization Uses tiny gyroscopes to detect movement Optical Image Stabilization
Lens shifts the optical path, to stabilize the image Unique to the lens; extra $ for each lens Canon, Nikon, some Sony, Panasonic
Sensor shift Sensor is moved to stabilize image Works with all lenses, even old film lenses Olympus, Pentax, some Sony, Konica-Minolta
Digital Image Stabilization Used in some video cameras Computer changes the pixel region from frame to frame
Performance is rated in equivalent stops improvement
Turn image stabilization OFF when using a tripod
Filters Ultraviolet
Mostly to protect the lens Cheap, and nearly invisible in the image
Polarizer Reduces glare Rotate for best effectiveness
Infrared Sees heat, for an ‘other-worldly’ effect
Neutral Density Reduces light, without shifting colors
Color Highlights individual colors
Gradient Neutral density on one end to clear on the other Great for darkening skies
Flash
Obviously used to brighten a scene Flash power is determined by the Guide
Number GN = distance x aperture, at a specific ISO Example: 18m at ISO 200 (Olympus E-5 internal) Means that at f/5.6 and 200 ISO, anything beyond
3.2 m (~11 ft) will not be fully illuminated External flash
GN is typically about 30 to 50 Can be moved off-axis, to control shadows Many are remote triggered; can use multiple units
Gadgets
Tripod Shutter release/ Remote control Monopod Ballhead Quick release Camera Bag Lens caps Spare batteries Screen protector Spare memory cards Reflectors/ diffusers GPS data tagger The list goes on and on…
What next?
Now that I figured out my camera and I’m taking great pictures, I have a bunch of pretty files. What can I do with them? Photoshop Elements
If you think they look great now, just wait… Elements has the same basic tools at ~1/10 the price
Prints Costco, Target, Wal-Mart, etc. Probably not worth using your own printer▪ Usually clog up if you don’t print a lot of pictures
Create a photo book about a subject (cheaper than you think) Online software and Elements both make it pretty easy
Post them online Recommend a Flickr free account Photo Club Flickr site – we want to see what you’ve done! Facebook, other social media
Digital photo frame display
Recommended References Your camera User’s Manual – read it!
Download it for easy searching at home Carry it in your camera bag for reference
Web sites www.penncamera.com www.DPReview.com www.learnmyshot.com www.photoextremist.com Wikipedia
TV show Wild Photo Adventures Magazines
Digital Photo Popular Photography
Exercises (mostly for DSLRs)
Depth of Field Select a subject separated from a detailed background, or an inclined
floor (grass or carpet) Use manual focus on the subject and aperture priority mode Shoot a set of images at each of the whole stops (2.8, 4, 5.6, 8,…) Compare the area in focus in each
Repeat, but changing ISO by full stops and keep constant f/8 Notice where the image starts to get grainy for your camera
Repeat, but changing only the white balance Which image matches reality? Did Auto WB pick correctly?
Speed Use manual focus and shutter priority mode Focusing on the street, hold your camera steady, and shoot images of
moving cars at 1 sec, ½ sec, ¼ sec,… to the fastest your camera will go Compare the ability to stop the action vs. shutter speed Also notice what happens to the steady background in each shot Do the same thing while panning
More Exercises
Minimum focusing distance Take a picture straight-on of a newspaper page, at
your lowest zoom focal length▪ Move closer, until the auto focus won’t focus any more▪ Repeat at the highest zoom focal length▪ Compare the highest magnification and the working distance
Image stabilization Hand-hold, without IS, in shutter priority, and take
longer and longer exposures of the same sharp subject▪ Where does the image get soft?▪ Repeat with IS on, if you have it▪ Repeat at different zoom focal lengths
