Photography by wanghonghx


									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
                                                                          your image.

                                                                          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.
                                                                       than 150ms.
                                                                    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
                                                                                                           of        digital
     the lens decides the "angle of view" of a picture. For
                                                                                                           photography, be
     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


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