Langford’s Advanced Photography 7th Edition

2 LANGFORD’S ADVANCED PHOTOGRAPHY

Because digital scanning backs physically track across the camera image plane throughout
an exposure, subject matter is limited to still-life as both camera and subject must remain still for
a couple of minutes. Therefore they cannot be used with flash, and using tungsten illumination
you must avoid any lighting intensity variations (such as minor flickering) because this will show
up as a band across the picture. A full colour image of many millions of pixels is built up line by
line to give image files at the top end of the scale of over 400 MB.

Clearly, dealing with files of this size is a completely different matter compared to the
convenience of using digital SLR. There are huge storage requirements involved and processing
must be done predominantly on a peripheral computer, therefore digital large format is much
more likely to be used in a studio setting than its analogue counterpart.

Comparing digital and silver halide

camera equipment

Advantages of digital:

● You get an immediate visual check on results (for example, displayed on a large studio monitor screen).
● No film or lab costs, or liquid processing in darkrooms.
● Sensitivity can be altered via ISO speed setting to match a range of lighting conditions.
● Exposure can be checked using the histogram to ensure correct scene intensity/contrast and to prevent

highlights being ‘blown out’.
● You can erase images, and reuse file storage, on the spot.
● Colour sensitivity is adjustable to suit the colour temperature of your lighting.
● Camera images can be transmitted elsewhere rapidly and wirelessly.
● Digital image files can feed direct into a designer’s layout computer – ideal for high-volume work for catalogues, etc.
● Extensive ability to alter/improve images post-shooting.
● Digital image files are theoretically permanent, if correctly archived.
● Silent operation.

Disadvantages of digital:

● Much higher cost of equipment; this includes powerful computing back-up with extensive file capacity (RAM)
necessary for high-resolution work. The technology is continuing to develop, meaning that equipment may
require frequent updating, another source of expense.

● There are a huge range of knowledge and skills required to keep up with changes in the imaging systems, to
ensure that your methods match standard workflows within the industry and to maximize the potential of the
equipment. This needs extra investment from you in terms of both time and money.

● Digital workflow is not simply restricted to capture, but requires an imaging chain consisting of other devices
such as a monitor and printer.

● Correct colour reproduction of a digital image from input to output requires the understanding and
implementation of colour management which is a complex and still developing process.

● Silver halide film still offers excellent image resolution at low cost – roughly equivalent to 3 billion pixels for every
square centimetre of emulsion. Also colour prints, particularly in runs, work out much cheaper by traditional
neg/pos chemical methods.

● The limits to final acceptable image size are highly influenced by the number of pixels per inch the camera sensor
codes within a file. So when planning a large final print you must start with a camera delivering sufficient pixels.

● High-resolution systems based on scanning are limited to still-life subjects.
● Cameras with digital sensors, like computers, are adversely affected by heat (i.e. from tungsten lamps).

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CAMERA EQUIPMENT 2

■ The 35 mm film format is the smallest used by sectors of the professional photography SUMMARY
professionals. These systems are the most market still work with film.
portable, versatile and the cheapest, with the ■ Professional digital camera systems aim to
largest range of accessories. Using 35 mm match image format and resolution for the
camera equipment you gain the benefit of latest three main formats used in film systems.
technology at competitive prices. However, ■ Currently, digital cameras use one of two
equipment may be either too automated or types of image sensors, the charge-coupled
offer excessive options which get in the way. device (CCD) or the complementary metal-
Consider manual override to be essential. oxide semiconductor (CMOS), both of which
■ Medium-format cameras offer a sensible use a silicon-based ‘array’ of picture sensing
compromise between equipment mobility and elements (pixels) to convert light falling on the
final image quality. As well as SLR and direct sensor into electronic charge.
viewfinder types, shift cameras and monorail ■ Once the image has been recorded on the
designs are made for rollfilm format. Often image sensor, it is processed, transferred off
they allow use of interchangeable film the chip, and stored as an image file,
magazines, instant picture and digital backs. consisting of binary digits (‘Bits’) representing
However, equipment is expensive, and has a the image data. If archived properly, a digital
smaller range of lenses than 35 mm. Using this image file may be stored permanently and
format also means less depth of field and reproduced as many times as required without
narrower choice of film stock. any loss of quality.
■ Large-format view cameras demand a ■ Digital images are sampled: spatially, they
slower, more craft-knowledgeable approach. consist of discrete non-overlapping elements
They tend to be expensive, yet basic. The range usually arranged in a rectangular grid. They
of lenses is limited, with relatively small are also sampled in terms of their colour values
maximum apertures, but most often give (quantized), as pixels may only take a fixed
excellent coverage to allow you to utilize range of values, determined by the bit depth
comprehensive movements for architectural, of the image file. These two factors determine
still-life and technical subject matter. You can the image file size, ability to represent fine
shoot and process pictures individually, and detail and ultimately the quality of the final
their size means that large prints show unique image.
detail and tonal qualities. ■ Resolution has a number of different
■ It is vital to have reliable camera technique – meanings in digital imaging and it is useful to
get into the habit of routine precautionary understand these different definitions.
checks before and during shooting. Look Fundamentally it describes the detail-recording
through the back of the empty camera to see ability of an imaging system. Resolution of a
that the shutter, aperture and flash work and digital image is normally expressed in terms of
that there are no obstructions. Take an instant- number of pixels. Resolution in a digital camera
picture shot before and after a session. Carry a also refers to number of pixels, but may refer to
spare body or some back-up camera; an exposure interpolated resolution rather than the real
meter; spare batteries – plus a screwdriver. resolution of the chip and can therefore be
■ Digital imaging is now the dominant means misleading as a figure of merit. For other
of image production for the consumer devices, resolution is usually quoted in terms of
photography market, but remains a numbers of pixels (or dots) per inch – this
developing area. The high cost and limitations defines the level of detail captured at input and
of larger digital formats mean that certain the dimensions of the image at output.

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2 LANGFORD’S ADVANCED PHOTOGRAPHY

■ Although the front-end design of digital aimed at the serious amateur, are usually SLR
cameras, particularly for professional formats, in design and tend to have many of the
is the same as that of film cameras, digital features of professional 35 mm cameras.
cameras have a number of features and ■ For the professional market, a number of
settings not required with film. These are manufactures now make 35 mm full-frame
changed via a software user interface, either SLRs, which are designed to match their film-
on an LCD screen on the back of the camera or based equivalents in terms of quality and
remotely using a peripheral computer. This features. These are currently significantly more
offers you a huge range of options at your expensive than either the film versions or the
fingertips, but it adds an extra layer of semi-professional SLRs.
complexity to the capture process, however ■ There are a range of medium-format digital
this is counterbalanced by the ability to view camera systems available. A few manufacturers
immediate results and adjust as necessary. make SLR cameras, but many professionals opt
■ Digital camera settings to change the white for digital backs designed to be used with
balance of the sensor and ISO speed rating to existing equipment. Currently, the sensor
match illumination means that a wider range dimensions are smaller than the 120 mm film;
of imaging conditions are catered for by the however image quality is generally regarded
same sensor. Correct exposure in digital as equivalent.
cameras is further aided by the image ■ Large-format digital systems are usually
histogram, allowing fine tuning of brightness digital backs containing either an area CCD
and contrast. In film systems sensitivity and array of smaller dimensions than large format
colour balance is achieved using different film films, or a tri-linear array of CCD elements
stocks and filters and is therefore a more scanned across the image. Full-frame sensors are
complicated and time-consuming process. more difficult to successfully manufacture to this
■ The physical dimensions of digital image size. The scanning backs, which do match the
sensors vary widely and are often smaller than imaging area of the equivalent films, require
film formats. This has implications for the optics still-life subjects and non varying light sources to
of the cameras, as the smaller format means prevent image artefacts such as banding.
that shorter focal length lenses will produce the ■ The decision to move to a digital workflow
same field of view as those used on film requires careful consideration. The technology
cameras. Shorter lenses mean smaller cameras continues to evolve and equipment will need
and larger depth of field. More recently to be updated on a more regular basis than
professional cameras containing full-frame film-based systems.
sensors that are the same size as their ■ Digital camera systems are more expensive
equivalent film format have been developed. and require understanding of a range of
For these cameras, there is no change in terms different issues on top of those required for
of field of view or depth of field when lenses film photography. However, the versatility of
for equivalent film formats are used with them. the systems and the ability to view and alter
■ Digital camera systems may be loosely images immediately post capture offer
classified according to the market that they profound advantages compared to the time
are aimed at. The largest section of the market required to produce an image using film.
comprises compact cameras and mobile phone ■ Top-end digital cameras can deliver results
cameras. These vary hugely in design and fully the equal of equipment using silver
features. More expensive than these are semi- halide materials; capital cost is far higher,
professional (Prosumer) cameras, which are although reducing every year.

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CAMERA EQUIPMENT 2

1 This project involves the use of the Adobe RGB and file format to JPEG (high PROJECTS
histogram as an exposure tool: quality).
(c) Take shots of each scene using the
(a) Set up a still-life scene using a variety of different white balance methods available: (i)
objects, including a test chart, if you have one, Auto-white balance, (ii) Pre-set to the light
such as the Macbeth colour checker chart. If not, source or colour temperature and (iii) Using
ensure that there are a range of colours in the custom white balance (you will need to check
scene and that there is one white, one black and the instructions for the camera to do this – it
one mid-grey object included. Set the lighting so usually requires a reference frame of a white
that there is a range of approximately seven object).
stops between shadows and highlights (you can (d) Download the images to your computer
check this by zooming in and taking exposure and view them side by side on screen in an
readings from these areas). imaging application such as Adobe Photoshop.
(b) Ensure that a memory card is in the Identify the method that works best for each
camera, turn the camera on and perform a light source.
complete format. Set the speed to 200 ISO. Set
the colour space, if possible, to Adobe RGB. 3 This project involves the capture of a scene
(c) Take 5 bracketed exposures, in using the different ISO speed settings to
increments of 1 stop, from 2 stops below investigate the effect on image quality and
correct exposure to 2 stops above. noise levels:
(d) Ensure that the histogram is displayed
when the images are played back. Examine how (a) Use the camera on a tripod for one
the shape of the histogram changes as the scene in daylight conditions and another scene
exposure changes. Identify the point at which with low light conditions (not night
shadows or highlights within the image are conditions, but indoor using natural light, for
clipped – this will show on the histogram as a example).
peak at either side. Your camera LCD screen may (b) For each scene shoot a range of images
also display clipped areas within the image. using all the possible ISO speed settings on
your camera.
2 This project involves investigating the ease (c) Download and examine your images in
of use and results obtained using the different Photoshop. Zoom into areas of shadow and
methods of setting white balance in your mid-tone.
camera: (d) Identify at which ISO speed noise begins
to be visible and in which areas it is most
(a) Select a number of scenes under different problematic. You may find you get different
lighting conditions, e.g. daylight, tungsten, results depending on the lighting conditions.
and fluorescent. In each, include a white (e) You might want to further extend this
object, such as a sheet of paper, and a mid- project by trying out some noise removal
grey object, such as a Kodak grey card. techniques (see the Image Manipulations
(b) Set the speed to 200 ISO throughout. chapter).
Find correct exposure, set colour space to

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3 Choosing
lenses

Fine image quality depends a great deal on having a good lens, but you will find that even
good lenses are only intended for a limited range of working conditions. Optics which
excel under one set of circumstances can give quite poor results under another. This
chapter explains some of the problems faced by lens designers and manufacturers, and shows
how every product is a compromise between what today’s technology will allow and what
we as photographers will actually buy. It also helps you to understand the lens quality data
in manufacturers’ technical literature, and what to look for when buying a lens, new or
secondhand. Special types of lenses are discussed too, in terms of practical handling and
suitability for different kinds of photography. With the recent increase in popularity of digital
still cameras (DSCs), consideration to the requirements of lenses for DSCs is given. The
advantages and disadvantages of using existing lenses designed for 35 mm film cameras in
digital single lens reflex cameras (SLRs) are examined.

The lens designer’s problems

We all tend to take a modern lens for granted. It is just accepted as an image-forming
collection of glass elements, somewhat overpriced and easily damaged. In fact, every
good lens is really a skilfully solved set of problems concerning the control of light.
Designing a lens means juggling image quality, the picture area covered, consistency over a wide
range of subject distances, an acceptably wide aperture – and finally coming up with something
which is not too large, heavy or expensive to manufacture.

Glass

The designer’s raw material is optical glass, which starts as a molten mixture of chemicals,

including barium, lanthanum and tantalum oxides. According to its chemical content, each type

of glass has a particular (1) refractive index

Substance Mean RI* (RI) and (2) dispersive power (Abbe number).
RI relates to the light-bending power of a
Vacuum 1.000
Water 1.333 glass. Since the RI of an optical material varies
Magnesium fluoride 1.378 with frequency and hence wavelength, it is
Fused silica 1.458 normal to measure RI at a specific wavelength.
Hard crown optical glass 1.519 This is done for several well-known emissions,
Common window glass 1.528 for example, the wavelength of light near the
Lead crystal drinking glass 1.538 middle of the spectrum (typically, 590 nm
Dense flint optical glass 1.927 yellow, see Figure 3.1). The higher the RI, the
Diamond 2.419 more steeply oblique light entering the glass is

*Measurement at wavelength 590 mm

Figure 3.1 Some refractive index values. changed in direction.

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