week 3 lens and focal lenghts

Week 3 Lens and Focal LengthsJoel 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

•Choose to extend 1 week, add an extra day, or go through the material quicker.

Agenda•Part 1▫Exposure settings/reading review▫Mode Dial▫Responding to photo pg. 170-171 review

•Part 2▫Critique Group Creative Mode assignment

•Part 3▫All about lens▫AF Mode

Metering Mode•Assignment

Exposure Settings Review

•Aperture •Shutter speed•Film speed- ISO

Aperture

Shutter SpeedsThe 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 apertureFor 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

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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

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Focal LengthChanging focal length alone does not change perspective

Lens-to-subject distance controls perspective

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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.

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 scenewill 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▫Canon 70 -300mm (112-480mm) $550▫Tamron 18-270mm (24-420mm), $700

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

1. Get Close2. It’s all about

Foreground3. Watch those

verticals4. Leading lines5. Focusing

Nordenskjöld Lake, Torres Del Paine National Park, Chile. Image Copyright Joe Decker

How to Buy a Lens

What type of shooting can’t you do?▫Far-away wildlife▫Action too fast▫Low-light pictures▫Scenic shots▫Portraits Handout

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

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The Perfect FocusSelecting Focus Mode

▫One-shot - Suitable for still subjects. Press the shutter halfway and the camera will focus only once. If the subject moves or you want to recompose the shot, you need to refocus.

▫AI Servo- “artificial intelligence” keep a continuous focus on moving subjects until the shutter is pressed all the way.

▫Al Focus- AI Focus mode starts with normal one-shot focusing but if the subject starts moving, it will switch to AI Servo mode.

The Perfect FocusSelecting the AF Area

▫Spot metering- useful if you often follow the rule of thirds – specific part of subject

▫Evaluative metering – all around ▫Center-weighted – weighted to the center

Reasons Not to Use Auto Focus

1. Not enough light2. Not enough contrast3. Shooting wildlife4. Landscapes and “hyperfocal distance”5. Fast moving objects6. Macro7. Rules of Thirds

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 properlyFooled by reducing the exposure1 stop

Assignment: Angle of View

Angle of View

Post two photos

Changing focal length alone does not change perspective