Pentax only produced the 100 mm macro-lens at the
time of testing,); Olympus only produces a 50 mm
macro-lens, which takes magnification differences
between analogue and digital formats into account.
The lenses chosen for this study were kept as close as
possible to a 100 mm equivalent (for 36 mm analogue
film). Nikon and Fujifilm use a small sensor, which does
not fill the 36 mm film-area. A magnification factor of
approximately 1.5 applies. This magnification factor was
adjusted by choosing a 60 mm macro-lens for those
cameras.
Methods
Ease of use
All cameras were initially set on automatic mode
(factory preset); with the flash turned on. The intra-oral
exposures were taken at approximately 1:2 magnifica-
tion. The aperture selected by the camera was recorded
and checked for suitability, particularly depth of field.
Homogeneity of illumination was checked for suitability
by assessing shadows on the image. There is a reverse
relationship between the f-setting and the aperture: the
larger the number of the f-setting the smaller the
aperture and the larger the depth of field. These settings
were found to be too small for all cameras (the aperture
was too large, giving poor depth of field) and were
therefore changed to aperture priority mode; the
aperture was closed to at least f522, which gives good
depth of field (Figure 2). The camera was then used for
extra-oral photography and the settings changed again
until appropriate, in this case an aperture of at least f58.
The number of changes necessary between the settings
was recorded. The camera was only considered metering
‘through the lens’ (TTL) if the flash settings did not need
to be changed.
Quality of the photographs: Color-fidelity
For consistency, intra-oral photographs (front, right
and left lateral views) were simulated by taking pictures
of a demonstration-model (Ormco), against a green
background (Figure 3). A non-clinical method was
preferred to taking images of a patient: the 10 cameras
were not all available at the same time and changes in
oral hygiene may have influenced color consistency over
time. Even if all cameras had been tested on one patient
on one occasion the discomfort would have been
considerable. The white balance selection was auto for
all cameras. The images were subsequently downloaded
on a ‘SONY VAIO’ (Sony Corporation, Japan)
computer. The computer screen was adjusted to project
Journal of Orthodontics JOR3338.3d 11/7/06 19:17:05
The Charlesworth Group , Wakefield +44(0)1924 369598 - Rev7.51n/W (Jan202003)
Table 1 Cameras tested and specifications
Body
Canon EOS
350D
Canon EOS
20D Fujifilm S3Pro
Konica -
Minolta 7D Nikon D100 Nikon D70s Nikon D50 Olympus E1
Olympus
E300
Pentax *ist
DS
Meagpixels (rounded figure) 8 8 12 6 6 6 6 5 8 6
Body (UK list price without
VAT in Euro)
770 1243 2206 1409 1348 858 746 1226 919 858
Flash MR-14 EX MR-14 EX SB 29S R 1200 SB 29S SB 29S SB 29S SRF - 11 SRF - 11 AF 140 C
Guide number 14 14 11 12 11 11 11 11 11 14
Macro Speed-light (UK list price
without VAT in Euro)
490 490 466 490 466 466 466 662 662 515
Macro - Lens 100 mm 100 mm 60 mm Nikkor 100 mm 60 mm Nikkor 60 mm Nikkor 60 mm Nikkor ED 50 mm ED 50 mm 100 mm
Macro - Lens (UK list price
without VAT in Euro)
588 588 539 919 539 539 539 453 453 551
Unit - Weight (in grams inclusive
batteries)
1612 1874 1891 2329 1765 1660 1605 1768 1688 1324
JO September 2006 Features Section Comparison of digital SLR cameras 3
