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GSFC Photography ClubBeginners ClassSessions 3/4 – Camera Mechanics
Scott Hull4/23/2015
Learn the rules like a pro, so you can break them like an artist.Pablo Picasso
Last Week’s Homework
Find your manual and check out your Metering modes Exposure compensation White balance … and how to change them!
Photograph a scene using different metering modes
Try it again with one metering mode but different exposure compensations
Try different WB settings
Review – ‘The Big Three’
Settings are all about what you want in the final product, but they’re usually a compromise
Shutter Speed (1/xxx sec) Faster to freeze action, slower to blur
Aperture (f/# ratio); higher # is smaller opening Larger aperture, blur foreground and background;
smaller aperture, sharper foreground and background
# is an indication of how much depth you will get Sensitivity (ISO)
How low can you go? Stay as low as possible Higher sensitivity means more noise
Review - Exposure
Combo of aperture, shutter speed & sensitivity
f/29, 1/2s, ISO 500
f/8, 1/8s, ISO 500
f/8, 1/20s, ISO 1600
f/4.5, 1/20s, ISO 500
Good Summary Chart
Review - Metering Modes Multi-zone (evaluative, matrix)
Evaluates whole scene (60% center, 40% other)
Center-weight (partial) Gives preference to exposure of central (~10%) area
Spot Gives preference to small (~2-3%) area in the center Gives precise control over exposure in a specific spot
Half-press the shutter release to hold the exposure
Exposure Compensation: shifts the exposure brighter or darker
Terms
Sensitivity (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 collecting
Optical vs. Digital Zoom Optical zoom is where 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 sec100 ISO 200 ISO 400 ISO
f/4 f/2.8 f/2 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 : √2=1.414 is the change
in diameter Most cameras now also use partial stops
Where are you as a photographer?
0 10020 40 60 80Neve
r took
a photo
Nat. Geo. every month
Everybody is somewhere between 1 and 99 As skills develop, you will want more capable
equipment Know where you are now, where you want to
end up, and how to get there (usually practice)
Camera Types
“Pocket” Camera
“Point and
Shoot” Compac
t
DSLRDigital SingleLens Reflex
ILC(Mirrorless)
Interchangeable Lens Compact
Differences Between Camera Types(in a very general sense)
Pocket Cameras + phones
Point and Shoots 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 monitor 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 available
Easy 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
Class will focus on entry-level DSLR, which covers most topics
Camera Parts
All digital cameras have: Lens Shutter Shutter release Sensor Computer Display screen Battery
Most also have: Viewfinder Built-in flash ¼ - 20 tripod mount
Some Have: Hot shoe Mirror / prism Beam splitter Grip Selection dial(s)
What’s inside a DSLR?Prism
Mirror
LensShutter
CCD Sensor
View Finder
¼ - 20Tripod Mount
Hot ShoePop-up Flash
Sensors(size does matter)
• Blue box is 35 mm film frame
• The difference (white area) is the crop factor
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
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)
Exposure Modes
Auto Camera selects everything: aperture, shutter speed, focus, flash
all of it, with no overrides Usually works well, sometimes disappoints
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
Fully Automat
ic
Semi- Automat
ic
Fully Manual
Shooting Modes
Single shot Burst
High/Low speed bursts Self-timer Mirror lock-up Remote control Bulb Bracketing for HDR
Scene Modes
Portrait Landscape Night
Scene Night
Portrait Sports Indoor Macro
Self Portrait Sunset Fireworks Food Documents Beach/
Snow Underwater
(4 options)
Snow Close-up Museum Backlight Panorama Candle Probably
many more…
A Few Common Scene Modes Sports
Increases ISO, opens aperture, 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) – should 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 Even experienced pros are starting to use it
instead of always manually focusing Still not always perfectly crisp Doesn’t work for all situations – moving subject
Very dependent on high contrast areas Focus point can usually be defined on DSLRs Might still need to tweak the ‘sweet spot’ Manual focus on pocket cameras and point
and shoots is difficult, if possible
Focus Modes, continued
Single Shot Autofocus Continuous Autofocus Single/ Continuous with manual
tweaking Manual Focus Live View focusing aid
Magnifies the Live View image Some ILCs offer this in the electronic
viewfinder
Metering
Average Original film approach, not used much anymore
Spot ~2-3% of the field Location is usually in the center, sometimes definable
Center-weighted average Central portion (~10%) 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▪ Compression losses occur each time it is saved▪ Usually several levels of compression available
Why not just maximize everything with RAW? Olympus E-5 Example (12.3 MP camera)▪ RAW file: 12.4 MB, High quality JPEG: 5.3 MB▪ Little discernible loss in image quality until you zoom in▪ In fact, RAW initially looks much noisier at high magnification
Memory cards are big, but not infinite capacity RAW is also not as portable between viewers
White Balance
Colors change based on the type of 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 incorrect Most DSLRs can also set WB manually for unusual
situations
Lenses
Built-in vs. interchangeable Depends on the camera type
Fixed vs. zoom Fixed is typically lighter and has 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
General rule of thumb for hand-holding an exposure: Shutter Speed < 1/Focal Length
They also tend to have smaller maximum apertures, leading to longer exposure times
Tripods help, but faster shutter speeds are more practical Tripod pointing is awkward and slow Faster shutter usually means higher ISO, though more noise
Thus, the driver for more expensive, “faster” zoom lenses
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
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: check the
manual
Memory
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 Camera Bag Lens caps Spare batteries 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 / Post-processing
If you think they look great now, just wait… Elements has the same basic tools at a lower purchase price
Prints Costco does a surprisingly good job cheap Probably not worth getting 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
Recommended References Your camera User’s Manual – read it!
Download it for easy searching Carry it in your camera bag for reference
Web sites www.DPReview.com www.learnmyshot.com www.photoextremist.com
TV show Wild Photo Adventures http://www.wildphotoadventures.com/
Magazines Digital Photo Popular Photography Photoshop Elements Techniques
Button, button, who’s got the button?
Power SwitchShutter ReleaseExposure CompensationPlaybackLive ViewDiopter AdjustmentLens Alignment MarkLens Release ButtonDepth of Field PreviewAF Point SelectionAuto-Exposure LockAperture Adjustment
Shutter Speed AdjustmentSensitivity AdjustmentSelf-TimerContinuous/ Sequential ShootingEraseFlash Flash AdjustmentWhite Balance
Backup Slides
37
Waterfall at various shutter speeds
Set camera to Shutter Priority Mode (usually “S” symbol) or manual (“M”)
For slow shutter speeds, go with higher f/# to let in less light (f/big number)
For extreme cases, or sunny days, put an ND filter on your lens for less light
For slow shutter speeds, use tripod or set on a rock Use a remote or self-timer to eliminate camera shake of pressing button
Shutter Speed in Seconds 1/800 1/200 1/30 1/3 1
http://en.wikipedia.org/wiki/Shutter_speed
Goddard Photo Club 38
What Is Aperture? Diameter of the lens opening Expressed as a ratio of the focal length to
the diameter (f-stop) Smaller f-stop number = larger diameter
11/13/2013
Goddard Photo Club 39
Aperture vs. DOF
Source: Fredrik Silverglimth, http://www.tutorial9.net/tutorials/photography-tutorials/depth-of-field-in-photography/
11/13/2013
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
RAW vs. JPEG
RAW: 12.4 MB JPEG: 5.3 MB
Olympus E-5; 12.3 MP camera(MD Renaissance Festival, 2011)
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
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
Mor
e D
epth
of
Fiel
d --
----
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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
Mor
e D
epth
of
Fiel
d --
----
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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
Mor
e D
epth
of
Fiel
d --
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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
Mor
e D
epth
of
Fiel
d --
----
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>