Photography

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for my computer, software for digital photo editing..... Money-wise, it ... The pros & cons of digital photography.
VOL.10 NO.12 DECEMBER 2005

Lifestyle Editorial

Photography 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 Photography has never been my favourite hobby until about 2 years ago when I bought a DSLR camera (digital single lens reflective, i.e. camera that can change the lens). It was a new model, the first of its kind that sell under 10K. Excited, I took a short photography course organised by the camera company where I learned a few simple photo taking & editing techniques. The techniques were simple but amazingly effective. When I started taking photo for my daughter (Beg my pardon, my wife too!), I realised I have fallen into the trap of the company. I was addicted to digital 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 was killing me was the time I spent on it. So be forewarned, unless you have ample time, don't try it!

of film processing company for developing your film. On the other hand, digital camera enables you to adjust ISO, white balance for each photo with the click of a button and you may "develop" your photo in your home computer. In other word, you are in total control so that it is hard to take a photo that is too bad to print. Archiving is also much easier than conventional photos. For an average user or amateur, digital photography offers convenient, fun and economy that conventional photography cannot match. The down side of digital photography is that it actually takes more time, effort, skills and knowledge from you if you are serious about your photos.

Choosing a compact digital camera Compact digital cameras (camera that cannot change 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 photos. 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.

The pros & cons of digital photography Compared with conventional film based photography, digital photography has distinct advantages. Firstly, the ability to preview your image not only makes you more certain about the quality of the image but also bring immediate feedback to the subject of the photo. This is especially important when taking photo for children. In fact, preview is fun even for adults. Secondly, digital photos are cheaper to take. You may take as many pictures as you like with no extra cost as long as you do not print them. The third advantage, and arguably, disadvantage of digital photography is the ability to control various aspects of your image during and after photo taking. ISO, white balance are set once you put your film-roll into a conventional camera. You are at the mercy

Several frequently under-reported but important properties relate to the speed of operation of a digital camera. "Boot-up" time of a digital camera is important for snap shot. If you are shooting children and events, you would like your camera to be ready to shoot as soon as you turn it on. I had a camera that took 67 seconds to be ready and by the time it was done, the subject was no longer interested. For compact camera, 2-3 second is acceptable. Shutter lag time is the time lag

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Lifestyle between shutter is pressed and the actual shutter release. It is important if the subject is moving such as children at playground. A pre-focus shutter lag time of 150ms to 200ms is noticeable but acceptable. A related property is the time required for the internal flash to re-charge. There are times when everybody freezes just to wait for your flash. Several seconds feel like ages.

VOL.10 NO.12 DECEMBER 2005

use a longer optical zoom. Digital zoom is a useless feature. For average user, I recommend the following specification: 1. Four to five mega-pixels. 2. Start-up time of less than 3 second, shutter lag less than 150ms. 3. Powerful internal flash with an effective range of 15 feet. 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

The property of preview is also important. Big LCD has the advantage of better preview picture but it sucks up electricity. I find movable preview LCD an extremely useful feature. I can view and take picture at odd angle that sometimes do wonders. Image histogram is a feature not many users know but it is actually a very useful tool for judging exposure. JPEG is generally an adequate archiving format if you are not going to do extensive editing on your photos. RAW is a format that store "raw" camera data: the original information captured by the CMOS/CCD without any alternation. Software is required to convert the data into image. The advantage is that you may alter many parameters, such as exposure setting without loss of image quality. However, image will be worse if you do not have the expertise to "convert" the RAW data. Unless you are committed digital photographer, RAW is not useful to you. Battery is another consideration. The ability to use generic 2A or 3A battery is a very useful feature. You may not want to bring the charger with you when you are travelling and it is also much cheaper. The number of photos a fully charged battery can take is also an important consideration. Last but not the least, is the optical component: the lens. 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 angle will cause significant distortion and long optical zoom may require some form of image stabilising 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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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 not for an under-exposed image. Try to take picture with exposure that put the peak of the image histogram on the right hand side. Digital photo is susceptible to colour cast and it may be difficult to remove. If your camera has a custom white balance function, be sure to know how to use it. It will save you a lot of processing time afterward. Use the lowest possible compression for JPEG. JPEG compression is lossy, that is, image information will be lost forever each time you make changes to your image. A low compression file withstands editing better than a highly compressed file. With storage device getting cheaper, there is no reason to compress your image beyond what is necessary. Be bold to experiment. Fully utilise advantage of digital photos as you can always delete unwanted images, try to take photo differently. You'll be amazed! Edit your digital photo. Simple editing can do wonder to your photo and therefore, to fully take the advantage of digital photography, be prepared to learn to use image editing software.