Lens sizes
Depth of Field
 Camera lenses come in different sizes:
 The longer the lens the more it enlarges the object
being photographed
 Lens are measured in mm…
 50mm is roughly the same as what we see with
the human eye:
 Less than 50mm (typically 24-30mm) gives wide
angles:
 And more than 50mm (typically 70mm+) zooms in
on a subject:
 A zoom lens is a jack of all trades lens that can
change its length from, say, 30mm to 70mm:
 Many digital cameras do not have a CCD
sensor that is as big as a 35mm film frame so
some cropping occurs
GEEKGEEK
ALERT...
 Depth of Field (DOF) refers to how much of a
photo is in focus
 Suppose you have focused on a person you want
to photo:
 The DOF is the distance you could move the
object towards or away from the camera without
having to re-focus:
 Everything outside of this zone will be blurred and
out of focus
>>> DEMO <<<
>>>DOF with zoom lens<<<
 There are three (four counting Photoshop) ways to
create shallow Depth of Field:
1. Use a long (70mm+) lens or a zoom
2....
 There are various setting on an SLR camera:
 ISO
 Shutter Speed
 Aperture
 They all adjust different aspects of your...
 Aperture adjusts the Depth of Field by changing
the size of the hole that light travels through to get
to your film/CCD:
 Basically, the smaller you set the f number to, the
smaller your Depth of Field:
 Changing the aperture means changing the
shutter speed to compensate (more next week),
for now…
 Set your camera to ape...
Narrow DOF
Wide DOF
>>> TASK <<<
 Put an a few objects on along a table
 Step back as far as you can and zoom in to create DOF
 Then get cl...
 On a bright summer’s day you will have to set
your aperture to a high number (f11 / f16) to avoid
over exposure…
 So se...
 Using an ND filter is a bit like putting sunglasses
on your camera
 What this means is that you can open the aperture
a bit more and get more Depth of Field
 ND filters do not effect the ...
 And, of course, Depth of Field can be faked using
Photoshop selections and a blur filter:
 >>> END <<<
Photography: 2 - Lens Sizes and Depth of Field
Photography: 2 - Lens Sizes and Depth of Field
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Photography: 2 - Lens Sizes and Depth of Field

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Photography: 2 - Lens Sizes and Depth of Field

  1. 1. Lens sizes Depth of Field
  2. 2.  Camera lenses come in different sizes:
  3. 3.  The longer the lens the more it enlarges the object being photographed
  4. 4.  Lens are measured in mm…  50mm is roughly the same as what we see with the human eye:
  5. 5.  Less than 50mm (typically 24-30mm) gives wide angles:
  6. 6.  And more than 50mm (typically 70mm+) zooms in on a subject:
  7. 7.  A zoom lens is a jack of all trades lens that can change its length from, say, 30mm to 70mm:
  8. 8.  Many digital cameras do not have a CCD sensor that is as big as a 35mm film frame so some cropping occurs GEEKGEEK ALERT!ALERT!
  9. 9.  Depth of Field (DOF) refers to how much of a photo is in focus  Suppose you have focused on a person you want to photo:
  10. 10.  The DOF is the distance you could move the object towards or away from the camera without having to re-focus:
  11. 11.  Everything outside of this zone will be blurred and out of focus
  12. 12. >>> DEMO <<< >>>DOF with zoom lens<<<
  13. 13.  There are three (four counting Photoshop) ways to create shallow Depth of Field: 1. Use a long (70mm+) lens or a zoom 2. Set a smaller aperture setting (f2.8 / f4) 3. Put a Neutral Density filter on your lens
  14. 14.  There are various setting on an SLR camera:  ISO  Shutter Speed  Aperture  They all adjust different aspects of your photo…
  15. 15.  Aperture adjusts the Depth of Field by changing the size of the hole that light travels through to get to your film/CCD:
  16. 16.  Basically, the smaller you set the f number to, the smaller your Depth of Field:
  17. 17.  Changing the aperture means changing the shutter speed to compensate (more next week), for now…  Set your camera to aperture priority mode (usually marked ‘A’ or ‘Av’on the control dial)
  18. 18. Narrow DOF Wide DOF
  19. 19. >>> TASK <<<  Put an a few objects on along a table  Step back as far as you can and zoom in to create DOF  Then get closer and take two identical photos – one on f2.8 and one on f16  If you don’t have these setting on your camera try using Macro mode and getting really in close…  …and/or take some photos that you can add DOF to later using Photoshop
  20. 20.  On a bright summer’s day you will have to set your aperture to a high number (f11 / f16) to avoid over exposure…  So setting a small f-number to get a small Depth of Field will not work  The solution is to put a Neutral Density filter on your camera…
  21. 21.  Using an ND filter is a bit like putting sunglasses on your camera
  22. 22.  What this means is that you can open the aperture a bit more and get more Depth of Field  ND filters do not effect the colour, only the amount of light reaching the film/CCD
  23. 23.  And, of course, Depth of Field can be faked using Photoshop selections and a blur filter:
  24. 24.  >>> END <<<

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