Week 3 Lens And Focal Lenghts

Week 3 Lens and Focal Lengths Joel Kinison “ If I saw something in my viewfinder that looked familiar to me, I would do something to shake it up. – Garry Winogrand Check out more of Hákon’s work at PhotoQuotes.com and www.Imageree.com .

Syllabus Update
Sep 28: Week 3: Lens and focal lengths
Oct 5: Week 4: The camera, lens attachments, filters
Oct 12 – No class
Oct 19: Week 5: Light and Exposure – Flash
Oct 26: Week 6: Digital Darkroom - Photoshop

Agenda
Exposure settings/reading review
Responding to photo pg. 170-171 review
Critique Group Creative Mode assignment
All about lens
Assignment

Exposure Settings Review
Aperture
Shutter speed
Film speed- ISO

Aperture

Shutter Speeds
The shutter-speed selector controls the length of time that the shutter remains open.
Understand that each progression represents half as much light as the preceding number. Common shutter settings are as follows:
1 second, 1/2, 1/4, 1/8, 1/15, 1/30, 1/60, 1/125, 1/250, 1/500, 1/1000, and 1/2000 second.

Film Speed
Film Speed Rating - ISO All film has a speed rating, whether digital or traditional. The ISO rating describes how quickly the film reacts to light.
Film speed uses stops, just like shutter and aperture For example, going from ISO50 to ISO200 buys you 2 stops more light.

Mode Dial
Basic Zone (Pre-Sets)
Portrait Mode Use this mode when you want a subject in the foreground in sharp focus.
Landscape Mode Use this mode when you want a wide-angle shot with the background in focus.
Night Scene (portrait) Mode Use this mode when you're shooting a subject at night. Illuminates the subject with the flash, while keeping the shutter open longer to provide more light for the background. Creates a balance.
Macro (close up ) Mode Use this mode for extreme close-ups. Blurs the background, narrow DPF.
Sports Mode For shooting scenes with lots of motion, which you want to capture without blurring .

Mode Dial
Creative Zone
P - Program - Program mode is much like Automatic mode - the camera will still do most of the setup work for you -- but it allows you to manually override some settings
TV - Shutter priority - used for manual shutter speed
AV - Aperture priority - used for manual aperture
M - Manual - used for fully manual control This allows you to manually adjust both shutter speed and aperture for the same shot, as well as focus.
A-DEP = Auto depth of field . All the focus squares are used to find the nearest and farthest objects in your viewfinder. The camera then calculates the best setting to give you the ideal depth of field.

Responding to photo pg. 170-171 review
Focus and depth of field
Motion
Light
Contrast and tone
Texture
Viewpoint and framing
Perspective
Line
Balance

Lens
Good lens is essential for crisp sharp photographs
Lens focal length - interchangeability

Lens Focal Length The focal length of a lens determines its angle of view, and thus also how much the subject will be magnified for a given photographic position. Wide angle lenses have small focal lengths, while telephoto lenses have larger focal lengths.

Basic Differences Between Lens
Lens are referred by their focal lengths
The focal length of a lens determines its angle of view, and thus also how much the subject will be magnified for a given photographic position.
The shorter the focal length of a lens, the more of a scene the lens takes in and the smaller it makes each object in the scene appear in the image

Size of Recording Surface Affects the Angle of View
With the same lens, a smaller sensor will capture less of a scene.

Conversion Factor
Most DSLRs on the market have nominally APS-C-sized image sensors, smaller than the standard 24×36 mm (35 mm) film frame.
While normal film cameras take 35mm film. The main reference point that people therefore use is the 35mm one which is considered ‘full frame’ size.

Crop Factor
Canon cameras such as the 300D/350D/10D/20D all have a 1.6X crop factor.
Nikon cameras such as the D40, D60, D90, D300 have a 1.5X crop factor.

APS-C Sensor Conversion Factor
Multiplying a lens focal length by 1.6 will give the 35mm equivalent
A 1.6x crop camera at 50mm is the same angle-of-view as 80mm in film or full-frame digital

Focal Length p.29

Focal Length
Changing focal length alone does not change perspective
Lens-to-subject distance controls perspective
p45

Lens Types

IS or VR
Canon's IS (Image Stabilization) and Nikon's VR (Vibration Reduction)
The IS/VR lenses give you a couple extra stops in low light situations
IS and VR are so important to helping get great shots Don’t buy a lens or camera without it, given the choice.
Even a point-and-shoot with IS is sharper than an expensive DSLR camera without IS in some conditions.

Example
A 1.6x crop camera at 50mm (same angle-of-view as 80mm in film or full-frame digital).
In general, if you shoot handheld, you can expect the shot to be free of shake most of the time when you shoot at 1/50 sec or faster. With newer IS/VR lens, you can expect to get shots 3 stops slower. Meaning about 1/6 sec.

Normal Focal Length
50mm,(35mm full frame)
Called Prime lenses
Normal lenses are faster
Dim light photography
More compact
Canon EF 50mm f/1.8 II Camera Lens
Niklor AF-S DX 35mm F/1.8
Most exciting is the speed of this lens - f/1.8 - that’s fast enough for many low light situations

Long Focal Length
Telephoto
100mm – 400mm
The angle narrows
What is shown enlarges
Relatively little DOF
Focal length increases, DOF decreases
Longer, heavier, expensive

Short Focal Length
Wide angle
18mm, 28mm
Shorter the focal length, the more of the scene will be sharp.
Wide-angle distortion

Zoom Lens
A zoom lens is a mechanical assembly of lens elements with the ability to vary its focal length (and thus angle of view), as opposed to a prime lens.
Zoom lenses are often described by the ratio of their longest to shortest focal lengths. For example, a zoom lens with focal lengths ranging from 100 mm to 400 mm
Sigma 120-400mm (180-600mm)
Canon 70 -300mm (112-480mm) $550

Nikon 16-85mm
Wide –to Mid angle, General purpose
Vibration Reduction (VR)
24-127mm DSLR
1:3.5-5.6
$600

Wide Angle Lens
Canon 10-22mm $710
16-35mm field of view
f/3.5-4.5 SLR Lens for EOS
Nikon 12-24mm $895

Using wide-angle lenses to create dramatic, effective images
Get Close
It’s all about Foreground
Watch those verticals
Leading lines
Focusing
Nordenskjöld Lake, Torres Del Paine National Park, Chile. Image Copyright Joe Decker

Olympus 7-14
Wide Non-fish eye angel
14-28mm DSLR
Broad stretches of distant bkgd
Tight interiors
1:4.0
price tag of $1500

Zoom, Macro & Fisheye
Zoom – combine a range of focal lengths
More expensive, bulkier & heavier
Relatively small max aperture
Macro-Close-up photography
Smaller max aperture
Expensive
Fisheye lens
Very wide angle

Tamron DI 70-200
Wildlife, close-ups
High-speed F2.8
70-200mm full-frame
109-310mm DSLR
Costly glass
Heavy
$700
Digitally Integrated' (i.e. optimized for DSLR use, but still covering the full-frame 35mm format),

Other lens
Fisheye view 10-17 $430
All around Tamron 70-200 $700
Close-up – portraits Tokina 100mm
Bright-fast F2.8
Is capable of life-size (1:1) magnification
$400

Prime vs Zoom Lens
Zoom
Range of focal lengths
Portability
Price in comparison to buying multiple lens
Flexibility
Less elements

Prime vs Zoom Lens
Prime
Quality – produce clean, crisp and precise shots.
Price – generally simpler
Weight – typically lighter
Speed – In general faster
Hazard weather

Automatic Focus Lock the Focus p.41

Making an Exposure of an Average Scene
Underexposed – too dark
Overexposed – too light

Manually Making the Fix

Meter Measures Light Subject Overexposed Automatic – average scene Subject Exposed properly Fooled by reducing the exposure 1 stop

Assignment: Angle of View
Angle of View
Post two photos
Changing focal length alone does not change perspective

Week 3 Lens And Focal Lenghts

by joelk on Sep 29, 2009

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