July 23, 2010
July 8, 2010
逆光攝影技巧
攝影是光的藝術，光的特性分為光度、光質、光位、光型等許多方面。對於一般的業餘愛好者來說，日常拍攝中最多遇到的可能就是自然光了，用日光拍攝有 利有弊，強大的光度可以保證足夠的色 彩表現，但如果需要特定的光色、光位就需要選擇正確的時間進行拍攝。特別是喜歡拍攝風景的朋友一定會了解，往往等待的時間比拍攝的時間要付出更 多。
拍攝人像要盡量避開正午的陽光直射、拍攝夜景最好是利用Magic Hour的黃金一小時，這些都是在無數次拍攝後的經驗之談，錯過了最佳的拍攝時段，陽光的色溫、角度都會有很大不同，得到精彩照片的概率也就相對難一些 了。不過事事無絕對，有時候正當你覺得陽光相當不適合拍攝，準備收起相機的時候，卻可以得到一些你意想不到的效果。
令人又愛又恨的光源：逆光
逆光，特別是日落時的低角度逆光往往會帶來被攝物體上的強烈陰影對比，造成很大的光比差別，在受光和背光的部分總有很多細節不能兼顧，更不用說逆光 拍攝了(編按：剪影也是其中一個可利用的技巧)。即便是那些價值上萬的高檔鏡頭，擁有較好的抗逆光性能，也難免在完全逆光的情況下出現眩光和自動對焦的障礙，對於普通鏡頭來說就會更加嚴 重。
不過事事無絕對，只要運用得當，結合良好的構圖，逆光拍攝也可以 得到美輪美奐的效果。在拍攝廣角風景、微距甚至人像的時候都可以採用逆光的光位得到不同的效果。
逆光拍攝時可以在物體周圍產生耀眼的輪廓光，強烈的勾勒出物體的外觀：
入門構圖技巧
初學者除了要對基本的器材運用(如測光、對焦)有認識外，構 圖也是其中一個非常重要的課題，好的構圖是拍出好照片的重要元素，各位一定要努力理解、學習和嘗試，Fotobeginner.com 的各位編輯會介紹不同的構圖法則、常犯錯誤和不同的構圖方法，好讓各初學者也能快速上手，現在便先看看一些構圖的基本法則吧！
(一) 適當取捨
其中一項初學者最易犯的問題便是"太貪心"了，很想把看到的全部拍進照片裏，但是這樣會使相片過於複雜、零亂，缺乏一個明確的主題，反而未能讓讀者 看到你想表達的主體。所以第一條法則便是要懂得取捨，作出適當的省略和裁切，魚與熊掌不要兼得，這樣相片的主題便會變得突出了。
(二) 主次要分明
主就是主角、主體，拍攝者最想表達的東西，而"次"就是配角，用來配襯出主角的存在。而在相片中我們可以用前景、中景、背景再配合景深、 距離遠近、位置、色彩等來達成主次分明，讓讀者有一個深刻的印象。
(三) 利用對稱與平衡
相片除了要有主題外，構圖也需要"平衡"，不能東歪西倒，否則讀者便不會看得舒服。拍攝時你可以嘗試把圖片在"視覺"上感到平衡，特別是"視覺"上 的輕重，我看過一本書，它把"視覺輕重"大致上歸納如下：
- 深色比淺色重
- 暗比亮重
- 面積大比面積小重
- 粗線比幼線重
- 密比疏重
- 近比遠重
- 山石比樹木重
- 樹木比水面重
(四) 構圖要穩重
穩重，其實就是不要令畫面"頭大身細"或"上重下輕"，常然不是要每一幅相片也四四正正，不偏不倚，但起碼感覺上不要"東歪西倒"，這個跟(三)的 對稱平衡也有關係，大家可以多參考。
我們可以利用對比來突出主題或令畫面變得有趣，基本上有5個¯以好好利用的對比方法：
明暗：利用一明一暗來帶出主題
大小：利用體積的大小比較來特出主題遠近：利用遠處的景物來突出近的主題(或相反)
顏色：利用顏色的鮮明對比來特出主題
高低：高低可以是實際的高度，也可以利用"仰視"來顯出"高度"，這個方法多用於拍攝建築物。
(六) 互相呼應
互相呼應其實也可視為運用對比的延續，有時兩樣獨立的東西出現在同一個畫面上便會發生有趣的"聯繫"，令讀者有一個幻想的空間，例如小孩的出現可以 襯托出大人，低小的山峄可以顯出另一個更宏偉的山峄，甚至帶出更深層的意思，看看以下的例子：
結論
構圖為一樣重要但比較抽像的東西，以上所介紹的只是一些基本的構圖技巧，但無論怎樣構圖，最重要的也是讓讀者看得舒服，能顯示深度和帶出意義更佳。 有關在實際構圖上遇到的問題將會另外撰文，請密切留意！
July 1, 2010
SPECIAL REPORT: ARE MARATHONS DANGEROUS?
Grave Concerns
SPECIAL REPORT: ARE MARATHONS DANGEROUS?
If running is so good for you, why do people drop dead during marathons every year? A lifelong runner, with help from the experts, finds the encouraging truth behind the scary headlines.
By Amby Burfoot
Deaths During Marathons
In the mid-1970s a California pathologist named Thomas J. Bassler, M.D., advanced the alluring theory that marathon runners might develop a sort of immunity from heart disease. He likened marathoners to the Masai warriors of Kenya and the Tarahumara Indians of Mexico-groups with little or no heart disease. "Marathon runners have much in common with these primitive populations," Bassler wrote. Runners everywhere repeated Bassler's tale to friends and skeptics alike. Then a trickle of case studies proved Bassler wrong, and the party was over.
Since the mid-1970s, three independent groups have collected data on heart-attack deaths during marathons. When the results are pooled together, we're looking at more than 4.5 million marathoners over the last 30 years. Of these, 41 runners died of heart attacks, a rate of one in every 110,476 marathoners. However, the two best of the three marathon studies have produced death rates somewhat higher than this average.
Family doctor and University of Minnesota Medical School professor Bill Roberts, M.D., has been medical director of the Twin Cities Marathon since 1985. Along with Barry Maron, M.D., a sudden-cardiac-death specialist also from Minneapolis, Roberts has gathered death statistics on both the Twin Cities and Marine Corps marathons going back to 1976. During that time, the combined marathons have had 525,700 finishers and seven cardiac deaths, an average of one death per 75,000 runners. Roberts and Maron have also found that this rate is declining, no doubt due to the increased availability of portable defibrillators. At Twin Cities, Roberts has established a goal of reaching any fallen runner with a defibrillator within five minutes. "If you're going to have a heart attack, a marathon is a great place to have one," he says. "Your chance of surviving is about 50 to 75 percent, versus five to 15 percent anywhere else on the streets."
In London, cardiologist Daniel Tunstall Pedoe served as London Marathon medical director from the inaugural 1981 marathon, which he ran in 3:19, through the 2007 event. Pedoe has studied marathoner deaths during all 27 London Marathons. Almost 712,000 runners have completed the race, with eight dying from heart attacks, a rate of one in every 89,000. The eight London deaths included five attributed to artery disease (cholesterol deposits) and three to structural heart abnormalities such as those that killed Ryan Shay and Chad Schieber. The deaths have occurred all along the course-at miles six, 10, 11, 12, 18, 19, 24, and in the finish chute. "Marathon running has a comparatively low, but not negligible, risk, and it's not surprising that people are frightened when they hear about a marathon death," says Pedoe. "That's why we have to keep educating everyone about the lifetime benefits of exercise."
Last December, barely a month after the deaths of Chad Schieber, Ryan Shay, and Matthew Hardy, the British Medical Journal published the biggest-by-far study of deaths during marathons. It was less definitive than the other two, however, since it relied on a search of newspaper articles to determine marathon-related deaths. Nonetheless, the BMJ study, conducted by Donald Redelmeier, M.D., from the Department of Medicine at the University of Toronto, surveyed 750 separate marathon days that were taken from 26 marathons over 30 years. The total number of runners in these races was 3,292,268, and Redelmeier found newspaper articles noting 26 heart-attack deaths. Hence, his ratio is one death in 126,000 runners. Redelmeier's most striking finding was that nearly half of all deaths occurred in the last mile of the race, or after the finish. This conclusion led Redelmeier to advise runners not to sprint at the end. In fact, in his one marathon, he deliberately jogged over the finish in 4:17. "I just tried to finish with a smile," he says.
Overall, Redelmeier concluded: "Clinicians interested in preventing sudden cardiac death might be surprised by the low risk associated with marathon running. [It's about] the same as the baseline hourly risk of death for a middle-aged man."
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