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

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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

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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

Mor

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epth

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