VOL.10 NO.12 DECEMBER 2005
Dr. Chun-bon Law MB, BS (HKU), MRCP (UK), FRCP, FHKAM (Medicine)
Consultant Geriatrician, Department of Medicine and Geriatrics,
Princess Margaret Hospital
Dr. Chun-bon Law
Prologue of film processing company for developing your film.
On the other hand, digital camera enables you to adjust
Photography has never been my favourite hobby until ISO, white balance for each photo with the click of a
about 2 years ago when I bought a DSLR camera button and you may "develop" your photo in your
(digital single lens reflective, i.e. camera that can change home computer. In other word, you are in total control
the lens). It was a new model, the first of its kind that so that it is hard to take a photo that is too bad to print.
sell under 10K. Excited, I took a short photography Archiving is also much easier than conventional photos.
course organised by the camera company where I For an average user or amateur, digital photography
learned a few simple photo taking & editing techniques. offers convenient, fun and economy that conventional
The techniques were simple but amazingly effective. photography cannot match. The down side of digital
When I started taking photo for my daughter (Beg my photography is that it actually takes more time, effort,
pardon, my wife too!), I realised I have fallen into the skills and knowledge from you if you are serious about
trap of the company. I was addicted to digital your photos.
photography. I bought books, extra lenses, extra memory
for my computer, software for digital photo editing.....
Money-wise, it was not cheap but still affordable. What Choosing a compact digital camera
was killing me was the time I spent on it. So be
Compact digital cameras (camera that cannot change
forewarned, unless you have ample time, don't try it!
the lens) in the market are generally quite good. Most
people do not make good photos mainly because of
inadequate skill and knowledge. Nevertheless, a
reasonable equipment is a basic requirement for good
Users generally have an impression that a 7 mega-pixel
camera will make better image than a 4 mega-pixel
camera. The fact is if you only view images on
computer monitor or print at 4R, there is hardly any
noticeable difference. Additional pixels is only of
significance if large scale print is required or if you crop
Several frequently under-reported but important
properties relate to the
speed of operation of a
The pros & cons of digital photography digital camera. "Boot-up"
time of a digital camera is
Compared with conventional film based photography, important for snap shot.
digital photography has distinct advantages. Firstly, the If you are shooting
ability to preview your image not only makes you more children and events, you
certain about the quality of the image but also bring would like your camera
immediate feedback to the subject of the photo. This is to be ready to shoot as
especially important when taking photo for children. In soon as you turn it on. I
fact, preview is fun even for adults. Secondly, digital had a camera that took 6-
photos are cheaper to take. You may take as many 7 seconds to be ready and
pictures as you like with no extra cost as long as you do by the time it was done,
not print them. The third advantage, and arguably, the subject was no longer
disadvantage of digital photography is the ability to interested. For compact
control various aspects of your image during and after camera, 2-3 second is
photo taking. ISO, white balance are set once you put your acceptable. Shutter lag
film-roll into a conventional camera. You are at the mercy time is the time lag
VOL.10 NO.12 DECEMBER 2005
between shutter is pressed and the actual shutter release. use a longer optical zoom. Digital zoom is a useless
It is important if the subject is moving such as children at feature.
playground. A pre-focus shutter lag time of 150ms to
200ms is noticeable but acceptable. A related property is For average user, I recommend the following specification:
the time required for the internal flash to re-charge.
1. Four to five mega-pixels.
There are times when everybody freezes just to wait for
2. Start-up time of less than 3 second, shutter lag less
your flash. Several seconds feel like ages.
3. Powerful internal flash with an effective range of 15
4. Lens as big as you can tolerate for a compact camera.
5. Movable preview LCD with histogram displace.
For even better quality, look for DSLR.
General advices on taking digital photos
Imagery in digital photo is coded in gray scale and
because of the intrinsic property of the light sensing
device; there is more information in the lighter area
of a digital image. Therefore, a slightly over-exposed
photo can be recovered and become a great photo but
The property of preview is also important. Big LCD has not for an under-exposed image. Try to take picture
the advantage of better preview picture but it sucks up with exposure that put the peak of the image
electricity. I find movable preview LCD an extremely histogram on the right hand side.
useful feature. I can view and take picture at odd angle Digital photo is susceptible to colour cast and it may
that sometimes do wonders. Image histogram is a
be difficult to remove. If your camera has a custom
feature not many users know but it is actually a very
white balance function, be sure to know how to use
useful tool for judging exposure.
it. It will save you a lot of processing time afterward.
JPEG is generally an adequate archiving format if you
Use the lowest possible compression for JPEG. JPEG
are not going to do extensive editing on your photos.
compression is lossy, that is, image information will
RAW is a format that store "raw" camera data: the
be lost forever each time you make changes to your
original information captured by the CMOS/CCD
image. A low compression file withstands editing
without any alternation. Software is required to convert
better than a highly compressed file. With storage
the data into image. The advantage is that you may
device getting cheaper, there is no reason to
alter many parameters, such as exposure setting
compress your image beyond what is necessary.
without loss of image quality. However, image will be
worse if you do not have the expertise to "convert" the Be bold to experiment. Fully utilise advantage of
RAW data. Unless you are committed digital digital photos as you can always delete unwanted
photographer, RAW is not useful to you. images, try to take photo differently. You'll be
Battery is another consideration. The ability to use
generic 2A or 3A battery is a very useful feature. You Edit your digital
may not want to bring the charger with you when you photo. Simple
are travelling and it is also much cheaper. The number editing can do
of photos a fully charged battery can take is also an wonder to your
important consideration. photo and
therefore, to fully
Last but not the least, is the optical component: the lens.
take the advantage
Lens is critical for image formation. The focal length of
the lens decides the "angle of view" of a picture. For
compact digital camera, because of the small size of
image sensing device (CMOS/CCD), an excessive wide prepared to learn to
angle will cause significant distortion and long optical use image editing
zoom may require some form of image stabilising software.
feature or high ISO setting to be functional. To test out
if the optical zoom of a compact camera is of practical
use, I recommend performing the following tests: 1. use
wide angle and shoot at objects with straight lines.
Look at preview for distortion. 2. Set the lowest ISO,
and under normal lighting condition, shoot at
maximum zoom. Magnify preview and check for image
blurring. In general, compact camera with a larger lens
can take better picture in low light condition and can