1. Lenses

2. Lenses define 2 important things: Angle of view (focal length) Aperture

3. Film/Sensor Where the light is recorded Lens Bends the light Trajectory of light Subject Source of light Focusing A look at the overall camera system

4. Light converges at sensor Light converges past sensor Light converges before sensor Result: ‘In focus’‘Out of focus’

5. Angle of view Camera sees a “cone” of vision, measured by the angle of the cone Narrow angles of view see very little, but the subject is big Wide angles of view see a lot, but the subject is small Wide angleNarrow angle

6. Translating focal length into angle of view Focal lengthAngle of view (degrees) 12mm121.97° 16mm107.03° 24mm84.06° 28mm75.38° 35mm63.44° 50mm46.79° 85mm28.56° 135mm18.21° 200mm12.35° 300mm8.25° 400mm6.19° 600mm4.13° For 35mm film sensor (diagonal: ~43mm) Focal lengthAngle of view (degrees) 12mm100.48° 16mm84.06° 24mm62.01° 28mm54.50° 35mm44.79° 50mm32.18° 85mm19.26° 135mm12.20° 200mm8.25° 300mm5.50° 400mm4.13° 600mm2.75° For 1.5x APS-C sensor (diagonal: ~29mm)

7. Translating focal length into angle of view Focal lengthAngle of view - APS-C sensorAngle of view - 5x4 Large format 90mm18.21°84.20° Lenses are always specified by focal length Photographers are concerned with angle of view (Depends on focal length and sensor size) Is 90mm a narrow angle lens, or a wide-angle lens? Problem: We want to talk in angles of view, but are given focal lengths Solution: We convert focal lengths to “35mm equivalent”

8. Translating focal length into angle of view Angle of viewFocal length - 35mmFocal length - 1.5x APS-CFocal length - 1.6x APS-C 121.97°12mm8mm7.5mm 107.03°16mm11mm10mm 84.06°24mm16mm15mm 75.38°28mm19mm18mm 63.44°35mm23mm22mm 46.79°50mm33mm32mm 28.56°85mm57mm53mm 18.21°135mm90mm84mm 12.35°200mm133mm125mm 8.25°300mm200mm188mm 6.19°400mm266mm250mm 4.13°600mm400mm375mm Actual focal length35mm equivalent focal length

9. Translating focal length into angle of view Angle of viewFocal length - 35mmFocal length - 1.5x APS-C 110.5315mm10mm 77.4127mm18mm 54.5042mm28mm 32.1875mm50mm 19.26128mm85mm 12.20203mm135mm 8.25300mm200mm 5.50450mm300mm 4.13600mm400mm Actual focal length35mm equivalent focal length To get the “35mm equivalent” focal length, multiply your actual focal length by the camera’s crop factor When we talk about focal lengths, we’ll assume they are “35mm equivalent”

10. Focal length ranges Two types of lenses: Zooms (variable focal length) and Primes (fixed focal length) Different focal lengths are useful for different things Standard range Covers most commonly used focal lengths, 28mm/wider, 70mm/longer General purpose photography Standard 18-55 “kit” lens is a standard range zoom 38mm

11. Focal length ranges Two types of lenses: Zooms (variable focal length) and Primes (fixed focal length) Different focal lengths are useful for different things Telephoto Gives a very narrow angle, 70mm and beyond Large magnification for faraway subjects Commonly used for sports, wildlife 320mm

12. Focal length ranges Two types of lenses: Zooms (variable focal length) and Primes (fixed focal length) Different focal lengths are useful for different things Ultrawide Gives a very wide angle, 24mm or wider Can cover extremely large objects in confined spaces Commonly used for landscapes, architecture, journalism 19mm

13. Tools for the job What focal length would you use for a huge building? What focal length for shooting sports from the sidelines? Covering a protest? Taking a portrait? 24mm 110mm

14. Tools for the job What focal length would you use for a huge building? What focal length for shooting sports from the sidelines? Covering a protest? Taking a portrait? 192mm 25mm

15. 24mm39mm 70mm Tools for the job Angle of view goes hand-in-hand with subject distance Subject distance defines perspective. Perspective affects: -Distortion -Context