Contents
Compositions
Camera Types
Camera Controls
Shutter Speed
Lenses Angle of View / Focal Length
Lens Types
Lens Controls
Depth of Field
F numbers
Exposure Metering
Bracketing
Film construction
Types of Film
Film Speed
Film Latitude
Film Spectral Sensitivity
Film Contrast
Filter Types
Flash and Studio Flash
Paper: Digital Photography
Assignment: Colourful Fruit
Appendix a – Shutter Speed Examples
Appendix b – Perspective and Camera Position
Appendix c – Depth of Field Experiments
Appendix d – Use of Grey Card and Filters
Appendix e – Film Types
Appendix f – Under and Over Exposure
Appendix g – Infra Red Film
Appendix h – Examples of Studio Flash
Appendix i – Examples of Digital Photography
Camera Types
Cameras are available in a variety of designs and film
formats to accommodate a wide range of applications. The five main types are as
follows:
Single Lens Reflex
The single lens reflex or SLR camera is a very common
design, which uses a pentaprism, allowing the operative to view ‘through the
lens’ using a mirror. At the point that the button is pressed the mirror lifts
up out of the way and allows the image to be projected onto the focal plane.
Some SLRs have a mirror, which drops down to allow the use of very wide-angle
lenses. Most SLR’s use a focal plane shutter, which is either a curtain
(fabric) type or a metal type. The advantage of this is that each lens does not
have to contain a shutter mechanism and thus reduces the cost of each lens.
Shutters can be either mechanically timed or electronic. The latter obviously
requires batteries and is often regarded as a disadvantage. Film is
advanced and rewound via a manual winder or an electronic motor wind. In
addition the cameras will have a method of assessing and setting the film speed
(modern electronic cameras use optical DX coding to automatically set the ASA
or film speed, older cameras are set manually. Flash sockets for the use of
external flash guns and studio equipment are also normal.
SLR
formats
35mm
Designed to utilise a 35mm
cartridge film. This is by far the most common type of SLR. Popular brands of
35mm SLR are:
Nikon
Pentax
Minolta
Canon
Medium
Format
Designed to use 120 roll film.
Medium format cameras are used by professionals who require a larger film area
for more ambitious prints and for digital scanning. The 120 roll film will
support many configurations in the medium format range:
6cm
x 4.5cm
6cm
x 6cm
6cm
x 7cm
6cm
x 9cm
Popular brands of Medium format
SLRs are
Hasselblad
Pentax
Mamiya
Bronica
Twin Lens Reflex
The twin lens reflex camera works in a very similar way to
an SLR with the exception that the lens unit contains two lenses, one for the
film and one to look through. The need for a movable mirror is therefore
negated, however it does mean that the lenses are more costly to manufacture.
The advantage of this system is that the user does not loose sight of the
object as the mirror lifts, but this advantage is offset by parallax error
created by one lens being on top of the other. Parallax error is accentuated
when objects are closer to the camera. Most TLR’s do not have interchangeable
lenses and are limited in flexibility.
TLR
formats
The majority of TLR’s are medium format and 6x6 format.
There are a few
Exceptions such as a mini Rolleiflex. Popular brands are:
Rollei
Mamiya
Seagull
Yashica
Rangefinder
A
rangefinder camera is light, small and quiet in comparison with an SLR or TLR,
the operator views through a sighting lens which does not ‘look down’ the lens,
so it does not require a pentaprism or mirror. It has some disadvantages as a
result of this, the main one is parallax error which is generated by having the
viewing lens offset from the lens. Some cameras have lines ground into the
viewing lens to assist in the sighting. In addition to parallax error, the
rangefinder also has to use a device to measure the distance to the object
which the operator is focussing and then the lens is set accordingly. This
device is unsurprisingly called a ‘rangefinder’. Rangefinders are often used in
reportage photography due the light, quiet nature and often the camera is
completely mechanical with the exception of the light meter.
Rangefinder formats
Rangefinder cameras are available in a variety of formats from the 35mm ‘happy snappy’ and disposable camera, and the panoramic ‘X-Pan’ type cameras. In addition there are 6x7 and 645 medium format cameras available from Mamiya, Fuji and the like.
Digital
Digital cameras are different from normal film cameras in
that the data is stored in electronic format as opposed to film. Digital
cameras are available in rangefinder and SLR style, the latter being very
expensive. Many medium format cameras with removable backs have digital backs
made for them. The media is often a smart card or CDR in the cas of new Mavicas,
which allows portability or directly connected to a computer for higher
resolution photography. This course module is an introduction to photography
using traditional means and an in depth discussion of digital media is not
needed.
Monorail
A monorail
camera is a type of large format camera which uses sheet film usually 5”x4” or
10”x8”. There are other film sizes available but not often used. A monorail or
technical camera is a completely different camera to those discussed
previously, they are technically demanding to use, very heavy and not very
portable, cost a great deal of money and in general are not used by hobbyists.
However there is no doubt that in terms of quality, creativity and flexibility
these cameras are second to none. The general construction is a lens board and
a backboard (which houses the viewing screen and the film) connected by a set
of light tight bellows and mounted on the rail. The boards have independent
movement up, down, tilting and swivelling and also longitudinally along the
axis of the rail. Lenses are changeable via the lens board and the shutters are
all of leaf type. The operation of these cameras is entirely manual and
requires a good deal of skill.
Makers of Monorail cameras:
Cambo
Sinar
etc
Field Camera
A field
camera operates very much like a monorail camera but is smaller, lighter and
designed for portability! The movements are restricted due to the ‘box’
construction which enables the camera to be folded away for transport.
Makers of Field cameras
Linoff
Polaroid
Camera Controls
Important parts of the camera are:
1.
Film rewind crank – for rewinding the film after use
2.
ASA setting ring – this interacts with the light meter for
calculating the automatic shutter speeds in Aperture Priority Auto mode
3.
EV +/- ASA dial lock – this allows the EV (exposure value)
to be set up or down using the calculated EV as a base.
4.
Hot Shoe – for housing a flash unit
5.
Shutter speed selection dial – shutter speed is the time
that the film is exposed to the light.
6.
Shutter release button – the button which opens the
shutter
7.
Film advance lever – winds on the film to the next frame.
8.
Multiple exposure button – depressed to prevent the film
from being wound on despite the shutter being re-cocked.
9.
Frame counter – displays how many frames of the film have
been used.
10.
Carry Strap bracket – for attaching a strap
11.
Depth of Field preview – allows the user to view though
the lens with the aperture ring stopped down.
12.
Self Timer – delays the shutter release from the
depression of the button.
13.
Lens release lever – allows the fitted lens to be removed.
14.
Focusing ring – facilitates focusing
15.
DOF indicator – Gives a visual indication of the depth of
field
16.
Aperture ring – changes the aperture of the lens
17.
Exposure lock – when using auto exposure mode this allows
the user to read the light from one view and carry the settings to another view
18.
X synch socket – for connecting studio flash
19.
Film chamber – 35mm film canister sits here
20. Metal focal plane shutter – the shutter is a multipart shutter made from metal as opposed to a curtain type
21. Viewfinder eyepiece – allows the user to view the picture
22. Sprocket teeth – ensures correct alignment of the film
23. Take-up spool – winds the film onto the spool as the film is advanced.
24. Film pressure plate – keeps the film flat and true ducting exposure
25. Camera back - cover
26. Power winder coupler – allows a motor wind on to be fitted
27. Rewind button – allows the film to be rewound
28. Film rail – keeps the film in line
29. Film guide rail – keeps the film in line
30. Tripod socket – permits the camera to attach to a tripod
31. Battery chamber cover – houses the battery for the light meter
32. Power winder electronic contacts – allows a motor wind on to be fitted
Shutter
Speeds
The shutter speed is the amount of time the film is exposed to the image through the lens. Modern cameras allow shutter speeds from 1/2000th second to several seconds. The shutter speed for a correct exposure is inversely proportional to the aperture. The actual numbers given for a shutter speed are normally incremented in ‘stops’. One stop higher is twice the duration and therefore 1 stop lower is half the duration. My camera has the following settings:
1/1000th sec
1/500th sec
1/250th sec
1/125th sec
1/60th sec
1/30th sec
1/15th sec
1/8th sec
¼ sec
½ sec
1 sec
2 sec
4 sec
Bulb – manual control for very long exposures.
It stands to reason that the longer the shutter is open for, the more light will be exposed to the film, so a correct shutter speed can be calculated for a given aperture in a given light level. For example:
|
Sutter Speed |
Aperture |
|
1/125th sec |
F 2.8 |
|
1/60th sec |
F 4.0 |
|
1/30th sec |
F 5.6 |
|
1/15th sec |
F 8.0 |
|
1/8th sec |
F 11.0 |
|
¼ sec |
F 16.0 |
|
½ sec |
F 22.0 |
Will all give the same exposure to the film. Using the shutter speed selector, the picture can be modified to give the desired effect for the photograph. Fast shutter speeds can freeze the action of fast moving objects such as sporting events or scientific applications. Slow shutter speeds can record the activity over long periods of time such as waterfalls, car headlights etc.
See appendix a for examples of shutter speed
Lenses
Traditionally lenses were single pieces of glass ground to a bi-convex disc which forced light to converge to a single point. This is known as a ‘simple’ lens, which has inherent image inaccuracies in the photographic arena. The focal length of the lens is the distance from the centre of lens to the point at which light coming from infinity converges to a single point as illustrated in this diagram:
In modern photography compound lenses are used to correct the optical imperfections of the simple lens. The compound lens is made up of several elements which means that it has no centre point. The calculated centre point is known as the rear nodal plane. This has the interesting characteristic if not necessarily being in the vicinity of the lens in all instances. This diagram illustrates the point:
Simple Lens
Compound Lens
Unfortunately, compound lenses have other inherent problems, mainly that of inter element reflection. Most lenses now are called coated or multicoated lenses, which minimise internal reflection. The advantage of the compound lens is that a 300mm lens does not have to be 300mm way from the focal plane of the camera, which makes lenses smaller and lighter. Conversely it is possible to produce wide-angle lenses with focal lengths of 20mm and below, this would be a problem as most SLR cameras have a space of at least 20mm between the focal plane and the lens mount.
Lens resolution is measured in Lines per inch, but since the advent of CAD in lens manufacture, the lens resolution has outstripped the ability of most film to render the resolution.
Lens focal length is proportional to image size and is therefore oblivious to the format of the camera. So as a result, a standard lens on each format of camera is different. This is generally calculated as the diagonal of the film size eg 60 mm x 70 mm using Pythagoras’ theorem the diagonal will be Ö602 + 702 = 92.2 = 90mm
Types of Prime Lens Table
|
35mm Lens Range |
Focal Length |
|
FishEye |
~18mm |
|
Ultra Wide |
~20mm |
|
Wide Angle |
28 – 35mm |
|
Standard |
50mm |
|
Telephoto |
50 + mm |
|
645 Lens Range |
Focal Length |
|
FishEye |
30mm |
|
Ultra Wide |
35-45 mm |
|
Wide Angle |
45 – 55mm |
|
Standard |
80mm |
|
Telephoto |
80 + mm |
Viewing angles
The angle of view of a lens is dictated by its focal length. The longer the focal length, the narrower the field of view. The illustration on the right gives a graphic indication of the angle for a 35mm camera.
It should be noted that although the viewing angles change with the focal length, an object taken with at distance a with a 50 mm lens will not produce the same result taking the same picture with a 28mm lens from closer in.
Please see appendix b for examples of Perspective and Camera Position
Lens
Types
The lens discussed previously have all been of Prime type, however there are several types which are described below:
Prime Lenses
Prime lenses are those with fixed focal length. Generally these prime lenses are faster and are of better quality than the other types. An explanation of faster is given later.
Zoom Lenses
A zoom lens has a variable focal length, for instance 28-70mm which allows the user to select the appropriate focal length for the task in hand. These lenses are relatively slow in comparison to prime lenses.
Fisheye Lenses
Although fisheye lenses are generally prime, it should be noted that these lenses are ‘uncorrected’ which means that the lines are not optically forced straight.
Shift Lenses
A shift lens allows the user to simulate the rise and fall of a technical camera on an SLR. Shit lenses are offensively expensive and have very specialised applications such as architectural photography.
Macro Lenses
A macro lens permits the photography of extreme close up shots. Macro facility is added to many zoom lenses. To convert a prime lens to macro the focal distance needs to be increased either by extension rings or bellows.
Mirror Lenses
Mirror lenses are long lenses which are made more portable by using a mirror to bounce the light up and down the length of the barrel to simulate a longer barrel. Using this method a 500mm telephoto lens can be made 150mm long.
Lens
Controls
Depending on how wealthy you are the lens will have some or all of the following controls:
Focusing Ring
The focusing ring allows the operator to fine adjust the focus of the image. This process is normally aided by a focusing aid built into the camera.
Aperture Adjustment Ring
The aperture adjustment ring allows the ‘F stop’ of the lens to be selected.
Shutter Speed
Cameras that do not have focal plane shutters control the exposure time from a leaf shutter in the lens. This is an attribute of large format and some medium format cameras.
Pentax 50mm Lens
Depth of Field
Depth of field is the area of the photograph, which is acceptably focused. The depth of field decreases with an increase in focal length. This chart is calculated from focusing the lens to 5’ and set at F22:
|
Focal Length of Lens |
Range of Sharp Focus |
|
20mm |
1.5’ – infinity |
|
28mm |
2.5’ – infinity |
|
35mm |
3’-20’ |
|
50mm |
4’-8’ |
|
85mm |
4.5’-5.7’ |
|
135mm |
4.9’-5.2’ |
This chart is supplied by Mamiya for the 645 Super:
Most 35 mm/ Medium Format lenses have a depth of field scale on the barrel which is used when the lens has been focused – see diagram.
Hyperfocal distance
When a lens is set to infinity focus at a given aperture, the nearest point to the camera which is acceptably sharp is known as the hyperfocal distance. If the distance is then set on the focusing ring then the depth of field will be from half the distance of the hyper focal length to infinity.
F
Numbers
F numbers or F stops are the diameter of the lens expressed as a fraction of the focal length. Eg a 50mm lens with a 12.5mm opening would calculate out as 50/12.5 or 4/1 which would be f/4 or f4.0.
The normal set of FULL stops is as follows
f1.0, f1.4, f2.8, f4, f5.6, f8, f11, f16, f22, f32, f45, f64, etc
As this series is based upon an area then the multiplying factor is Ö2
Modern lenses stop up and down in ½ or 1/3 stops as well as full stops.
Lens Speed
The bigger the aperture (smaller the f number) the faster the lens is described as. F1 lenses still cost a lot of money and are only available in prime lenses. Lenses are described as the lowest f number that is available eg 50mm f1.7
Exposure
Metering
Exposure metering is the process of reading the amount of light available to the camera and making a decision on which combination of shutter speed and aperture will give the desired result. This is also dependant on the film speed or ASA rating (described later)
Light meters return a reading to turn the whole scene to an average of 18% reflectance, mid grey or Zone V.
Exposure meters come in a variety of flavours but are primarily those which are integral to the camera and those which are hand held.
Integral Meters
Integral Meters or TTL metering uses a mechanism in the camera, which measures the light coming through the lens. The camera then reads the aperture (for AE exposure) and suggests the correct shutter speed. Modern cameras use centre weighting and other computer controlled patterns to ensure that the exposure is right. The software used is very sophisticated and some cameras even use memory sticks to store preset conditions such as seaside, snow, mountains etc. Although this is all very impressive, the camera still does not know what the subject matter is, so there is no substitute for doing the job by hand where time and circumstance permit
Hand Held Meters
There
are two types of hand held meter. Incident and reflective, incident requires
the operator to be close to the subject which is great for portraits but not so
good for landscapes. Reflective readings can be taken from the camera position,
but take readings of objects which may skew the result depending on the
reflectance of the object. For example if the reflective surface is a white
wall then the wall will be produced mid grey, which is not desirable.
Spot Meters
Spot meters can take readings from very localised objects. The accurate spot meters will read a 1 degree arc, less accurate meters read 5 degrees. Spot meters are very useful for reading grey cards.
Flash Meters
Flash meters read the amount of light that is delivered in a studio flash setup. Meters can be either set to wait for a big burst of light or operated by a synch lead. As most cameras will only operate at certain shutter speeds with a flash system, the meter just delivers an F stop.
Grey Card
A grey card is a piece of cardboard which has 18% reflectance. This enables the grey card to be read by whichever metering system is required and the meter should produce accurate results.
Bracketing and Under / Over Exposure
Under exposure and over exposure are errors in the exposure calculations, but bracketing is hedging ones bets. Some cameras will bracket a 1/3 stop either way of the mean. Bracketing ensures that the shot will come out as you intended. This is very useful with transparency as the exposure latitude is very narrow.
Film
Construction
Anti-scratch Layer
This layer protects the emulsion from physical damage
Emulsion
This layer contains the halides which form the photographic images
Adhesive Layer
This layer bonds the emulsion to the film base
Film Base
A transparent layer which supports the image
Adhesive Layer
This layer bonds the anti halation and anti curl layer to the base
Anti-Curl/ Anti-halation Coating
This layer prevents the film being exposed from the rear and stabilises the laminate to prevent curling.
Film
Types
35mm
Films
120 Films
5x4 Films
|
Formats |
Description |
|
APS |
Advanced Photo System – The film self loads and will produce a variety of picture shapes |
|
35mm |
The most popular format, sprocketed and supplied in a canister |
|
110 |
A small format cartridge film |
|
120 |
Roll film for medium format cameras |
|
220 |
A longer version of 120 film |
|
Sheet |
For technical, monorail & field cameras etc |
Black & White Print Film
Black and white print film produces a negative for printing onto photographic paper
Black & White Transparency Film
Black and white transparency film produces a slide for viewing through a projector or high resolution scanning
Colour Print Film
Colour print film produces a negative for printing onto photographic paper
Colour Transparency Film
Colour transparency film produces a slide for viewing through a projector or high resolution scanning
Film
Speed
Film speed in measured by a number of scales but the most common is the ASA (American Standards Association) or ISO (International Standards Organisation) depending on the country you are in. Each time the film speed doubles or halves, it is equivalent to 1 stop. A shot taken at f2.8 for 1/60 sec on Technical Pan could be taken at f32 on Delta 3200.
General Film Speeds are:
|
ISO |
Example Film |
|
25 |
Kodak Technical Pan |
|
50 |
Ilford Pan-F Plus Fuji Velvia |
|
100 |
Kodak T-Max 100 Inford Delta 100 Fuji Provia Kodak Gold |
|
160 |
Fuji NPS Kodak Portra |
|
200 |
Kodak Gold Fuji Superia Kodak ED |
|
400 |
Ilford Delta 400 Kodak T-Max 400 Fuji Provia Fuji Neopan |
|
800 |
Fuji NPZ |
|
1600 |
Fuji Superia Fuji Neopan |
|
3200 |
Ilford Delta 3200 Kodak TMX 3200 |
Film Latitude
The latitude of a film is the amount of exposure error the user can make before the picture degrades noticeably.
Black and White Print and Colour print film have quite a high latitude ie at least a full stop either side of the ideal. However slide film has a latitude of about 1/3 stop either side of ideal.
Film
Spectral Sensitivity
Film is receptive to certain regions of the electromagnetic spectrum
Panchromatic Film
Colour Films are generally sensitive to the whole of the range of visible light, however some films are balanced for specific lighting conditions which ‘corrects’ the film to show what we as humans would see. Examples are:
EXAMPLES OF COLOUR FILM FOR TUNGSTEN
Black and white films are, in the main panchromatic, which means that they are equally sensitive to light across the spectrum. Some examples are:
EXAMPLE B&W FILMS
Orthochromatic Film
Orthochromatic film is sensitive to the blue end of the spectrum, reaching the wavelength which produces green light, but not red. This film is still used today for line drawings and some graphic arts applications as well as the medical industry. Examples are:
Fuji UM-MA – Mammography film
Kodak Precision
Line Film LPD7 – Duplicate Film
Kodalith Ortho
– Lith printing film
Infra Red
Film
Infra red film
is used in both scientific and creative photography. It is a panchromatic film
which has sensitivity skewed to the red end of the spectrum. Examples of Infra
red film are:
Kodak High Speed
Infra-Red
Ilford SFX 200
Konica 750nm 120
Infra-red Film
Filters
Filters modify the light, which reaches the film by light filtration. Some filters are quite severe and some are just enhancers such as warm up filters. Colour and black and white filters are quite distinct but can cross over such as a polarising filter.
Here is a list of colour filters:
|
Filter |
Comments |
Factor(stops) |
|
1A |
Skylight – UV absorbing. Often used to protect the front of the lens and left in place permanently |
0 |
|
81A |
Warm Up |
1/3 |
|
82A |
Light Blue filter to eliminate Red cast |
1/3 |
|
80 |
Tungsten correction |
2 |
|
85 |
For using Tungsten balanced film outdoors |
2/3 |
|
FL |
For correction of fluorescent tubes |
1 |
|
Polariser |
Reduces reflections |
1 1/3 |
|
ND |
Neutral Density – has no effect on colour or tone, just allows longer exposure times |
Variable |
Here is a list of black and white contrast filters:
|
Filter |
Comments |
Factor(stops) |
|
#6 |
Yellow filter for moderately darkening blue skies |
1 |
|
#12 |
Deep Yellow filter or minus blue filter |
1 1/3 |
|
#11 |
Light yellow/green filter enhances blue skies and some foliage. Also corrects for tungsten lighting |
2 |
|
#23a #25 #29 |
Red filters of increasing severity which deepen blue skies and darken foliage. Also increases contrast in landscape photographs |
2 2/3 3 4 1/3 |
|
#47 |
Blue filter lightens the sky and darkens foliage |
2 2/3 |
|
#44 |
A cyan filter which simulates orthochromatic film |
3 |
|
Polariser |
Eliminates glare by only allowing light from one plane to enter the camera |
1 1/3 |
|
ND |
Neutral Density – has no effect on colour or tone, just allows longer exposure times |
Variable |