移軸鏡的新奇功效 Special Effect by PC Lens

上期的網誌我跟大家玩了一個沒有獎的問答遊戲，我給大家兩張用相同鏡頭以相同參數拍攝的照片，但照片顯然有所不同，現在，我們再一次看看那兩張相片吧	Last time in my blog I asked what makes the difference of the two pictures using same lens, same setting.  Let us see the two pictures again.
下面是那兩張照片，(A)全部清晰，(B)只有水平中間部份清晰： The following are two pictures I used as example.  (A) being clear and sharp while only the central horizontal part of (B) is sharp:
(A)	(B)
其實(A)是一般的拍攝方法，由於網門與鏡頭及感光元件平行，只要中間部份對焦，其他的部份也可以對焦，因此整個網門都影得一清二楚。 不過(B)圖中的鏡頭與感光元件並不平行，所以縱然調教到中央部份對焦，網門的上半部及下半部都不能合焦，形成這樣一個特別的效果。	Photo (A) is just taken by normal camera setting where the lens and the light sensitive element (CCD/CMOS) are parallel to each other.  As the door is also parallel to them, this will guarantee once a point is in focus, the whole door will be in focus too. In (B), the lens is not parallel to the CCD/CMOS.  Although the central part is in focus, the other part does not.
上面的貓照片，大家會發覺很奇異地只有最近鏡頭的眼睛是合焦的，其他部份，雖然與鏡頭的距離相若，依然不能合焦。原理也是一樣，是相鏡的鏡頭與感光元件並不平行所做成的。 不過，你會問，為何要弄到鏡頭與感光元件不平行呢？又如何才可以弄到他們不平行呢？ 其實答案是移軸鏡。	The same effect can be seen from the above picture of a cat.  To make the eye and only the eye in focus, I use a lens that is not parallel to the CCD/CMOS when I take this picture. Of course, you may wonder why we need to arrange them not in parallel and how we can do this. The answer lies in the production of PC (perspective correction) lens.
移軸鏡其中的一個作用就是讓鏡片的軸可以移離相機的主軸，這樣就可以產生一些特別的效果。 一般來說所謂移軸，可以是鏡片的主軸與相機主軸保持平行的平移，亦可以是把兩條主軸形成一個角度的傾移，前者不在這裡說明了，這裡只想說說傾移的一些效果。 下面是一幅我拿著相機在書枱前拍攝平放在書枱上一份文件的結果，由於相機與文件並不是相互平行而景深有限，所以只有部份文件是清楚的。	PC lens is a special type of lens that allow the lenses in it deviate from the principal axis of the camera so that special effect can be achieved. There are usually two types of movement of the lenses.  One is shift and the other is tilt. The effect of shift will not be covered here.  I will only say something about the effect of tilting the lenses. The picture below shows the effect of taking the photo of a document on a table when holding the camera near the table.  As there is an angle between the camera and the document and the sharpness is limited by the dof, only part of the document is sharp.
利用移軸鏡的傾移作用，在相同的情況下，沒有減少光圈，我可以得出下面的結果。	With the help of the tilt of the lens of a PC lens, I can obtain a much better result even thought I have not reduce the aperture of the setting.
原來光學裡有這麼的一條特別的原理，就是當鏡片的面與感光元件的面有所相交時，就會出現一個與他們一同相交的面，而這個面的所有部份都是合焦的。	The secret lies in a theory saying that there is a plane with which it meets the intersection of the lens' plane and film's/sensor's plane that the whole plane is in focus.  When the document is that plane, all the words in it can be read clearly.
好好的利用這個原理和一枝移軸鏡，我們就可以拍出比一般鏡頭有更廣清晰範圍的照片了。 不過，你亦可以反其道而行知，利用移軸鏡頭的傾移效果，把原本該是一清二楚處在焦平面的東西移離焦平面，使只有一小部份清楚，這正是我在上一篇網誌中所做的。多了一層技巧，也許在你設計你的照片時你可以做得比別人更加不同了。	Thus you can see we can obtain photos with wider "dof" by the tilting of a PC lens. However, no one limits you from doing just the oppose.  You can use a PC lens to deviate a plane that is in focus originally so that only a small part of it is in focus.  My last blog is showing pictures of this type.  Hope this will widen your ability in designing your photos.

冇獎遊戲

今日對住飛機籠隻門影左兩張相，如下

(A)

(B)

(A)同(B)都係在同一情景，同一相機同一鏡頭影，光圈快門都一樣，兩都都未有用軟件改動，不過(A)相整個飛機籠門都清楚，但係(B)就只有中間部份清楚，上下都失焦。想問，究竟點解會咁呢？

答中冇獎，答案下個blog解說。

村狗黑熊自白

我就係村中三黑B中地位最高的黑熊，平時好少有機會同大家見面，因為，村狗始終是村狗，有人關心已經萬幸，真不敢想可以做blog的主角。

我的歷史大家或者都知道一二，前面果個就係我biological 媽咪，佢對我地好關心，我地都咁大，佢仲周不時保護我地。樓梯上面果個就係囡囡，佢比我地早來到這條村，以前佢有個同伴叫仔仔，不過，因為受傷死了，之後我媽咪來了這裡，囡囡比佢留低，我媽咪叫做咪咪，生左我地幾個，有D比人收養左，但係我地有三個黑色的留低陪媽咪，除左我黑熊，仲有黑臉同黑妹。

我都唔知我daddy係邊個，不過你睇下我三七面個樣，你話似邊個呢？

最近媽咪經常比我四圍去，仲周不時可以坐在村中的路上。

仲可以出到行巴士的大路，見到路上面的牛牛。

我其實有D驚，我諗媽咪想我接手做村狗的領袖，但係這裡的生活危機四伏，身為領袖要識好多野，我閱歷又唔深，真係唔知是否可以做一個合格的領袖。不過囡囡同咪咪都係女生，加上囡囡年紀都大，一定要有狗接班，我們三兄妹中，黑妹女生又細膽，黑臉就最冇用，唔敢企出泥，我想唔做都唔得。

仲有，大家有冇見到我耳仔的白點，那不是什麼好東西，是我們狗狗的大敵牛蜱，我地連命仔都未必可以顧到，做領袖真係談何易容。都係先學下在地盆巡邏個款先...

~~黑熊上

無聊影幾張相玩下

枱面忽然多左個小funny monkey，不如同佢影張相，又當習作練習下佈光：

因為佢出世都好一段日子，個頭有D蹟，無辦法，不過佢個身通透精瑩，下面打燈影又真係好靚女。

順手影多幾張其他：

(1) 我屋企個無線電話

(2) 好靚的有葉橙

(3) 支135 DC F2人像鏡

張張相燈光setting都有D唔同，不過唔講了。

Capture the beauty of maple tree

九月十月間我去了一趟加拿大的多倫多，正值那裡楓葉轉紅的日子，本該是拍攝楓葉的好時節，可惜我帶同兩狗同行，照顧他們之餘已無能力拍照，所以沒有可見人的作品；但手頭剛有一本 11月12月的DIGI Photo雜誌，談的正是拍楓葉的事，雖說他的範例照片不甚了了，技巧也是老生常談，也不妨拿來分享。 工具方面，他提議你要有腳架，中長鏡加廣角鏡，外閃，CPL濾鏡及快門繩/遙控。 採光： 側順光最好，可以保有影像細節與層次，逆光運用得宜時可以拍出透明的質感，所以他提議的拍攝時間是早上7時到9時半及下午2時到4時半左右。 天氣： 他認為陽光好的日子可以有較艷麗的結果，也有藍天白雲作背景，因此要配合CPL使用，令天更藍，也減少葉面反光以增加楓葉的艷麗，但陰天也可以拍出另一番風味，雨天也可以把水點的效果，總之，天氣沒有選擇，不拍是損失。 曝光：盡量用RAW拍攝以便日後微調，他說只要1/3eV到1eV的加減，已經有戲劇性的變化。為了令風中微光之下仍然可以拍出清晰的效果，最好用高ISO及上腳架，有時亦要加外閃補光。 焦段：日本擁有楓林及楓葉大道，可以用廣角表現；要拍特寫時，當然要用中長焦，這時要考慮背景的顏色，不要選與楓葉同樣紅的背景。視角方便，可以考慮用大片藍天做背景，這時當然要加CPL及補光。	I have been to Toronto at the turn of Sept this year and was fortunate to see the beauty of maple leaves turning red.  However, my pictures on these leaves are nothing outstanding.  After returning Hong Kong, I see an article in the Nov+Dec issue of DIGI Photo telling us the methods we should employ in taking pictures of maple tree.  Although their sample pictures are just ordinary and the methods described should be known to us already, I think it is still worth to summarize it here. For the equipment to take with you, it suggested you should have tripod, tele and wide angle lenses, external flash, CPL and remote. As the best light is side light which would not flatten the leaves, the best time suggested for taking pictures of maple trees are from 7 to 9:30 in the morning and from 2 to 4:30 in the afternoon.  When you can manage the backlight, you can show the texture of the leaves. Sunny days would promise more colorful and saturate picture.  And you can add blue sky and white clouds as background.  Thus, use CPL to darden the blue sky for a even saturated result and CPL also cuts the reflection of the leaves to show its colors.  If it rains, you may try to shot the raindrops on the top of the leaves.  Thus, don't withdraw when you think weather is not promising.  Shot is also better than not shot. Try to take your pictures at RAW mode as it enables you to adjust its exposure later more easily.  A change of 1/3 eV to 1eV would make a dramatic change to the photo.  In order to deal with the wind, you should use high ISO and sometimes use flash to adjust the brightness of the trees/leaves. When you want to take the whole forest of maple tree, you have no choice but using wide angle lens.  When you try to take a closeup shot of a leaf on the top of a tree, you cannot do without a tele lens.  Try to make the leaf stand out from the background by choosing background other than red.  Can adjust your point of view so that the blue sky is used as background.  In this case, don't forget to add CPL and use flash to light up the leaf.
下面是幾張我在加拿大拍的楓照： The following are some pictures I took in Toronto:
不要忘記地面上也是一片楓葉地氊﹝我的太太及兩隻狗狗成了背景﹞	Don't forget the leaves on the ground (the leaves are so beautiful that my wife and my dogs get not noticed).
即將變紅的楓葉近攝，用藍天做背景，但未有加CPL	A closeup view of maple leaf.  Blue sky is used as background but no CPL.
天氣不佳，也不是不拍的借口	Don't give up when weather seems not promising
不是季節也不是罷影的借口，找個對比就可以拍了	Don't give up when it is still not the right moment.  You can show the contrast.
不必只影一片紅，要有多種不同的顏色才使畫面豐富，這也是沒有用CPL的呢	A mix of different colors is better than just color red.
紅葉不多時，找點別的興趣	When red leaves are too rare, you can concentrate on other things.

Tips on taking pictures on cats

有人在討論組中問怎麼樣拍貓，心想，自己也拍貓多年，其實有沒有任何心得呢，不如總結一下。所以，在討論中說了下面的觀點.... 找個簡單的背景，是你成功的主要因素，因為家中一般有不同雜物，拍出來的效果不好，好在貓兒細小，一塊白色的小牆足夠了。下面是在街拍的一隻流浪貓，由於背景為白牆，突出花貓的效果良好。

Someone asked in a discussion group how cats can be photographed beautifully.  Having taking cat photos for years, I assume I have my ways so I summarize the method I usually employed as below. A simple background is the keyfor success.  Luckily cats are small creatures that merely a small part of an empty wall is enough.  The following picture shows a street cat I shot with a white wall as background.

沒有簡單的背景，可以用大光圈虛化，不過效果未必管用。這是我家的貓，雖然用f2.8虛化背景，但仍然影響效果。

When simple background is not found, we may apply large aperture to blur the background.  This although helps but not necessary gives satisfactory result.  In the picture below I use f2.8 for my cat but the effect is only acceptable.

都是在家中拍的，用光差效果把背景除去。

Another method is to use different of brightness level to make the background looks dark.

焦距選擇方面，其實跟你要的效果掛勾吧，不過太廣角的話，要考慮貓兒跟你有多熟，可以有多接近，太長距離的話，家中的位置足夠工作嗎？ 這是50mm在D700全幅機拍的，50mm在我家中工作比較合適，由於是自己的貓，也不怕太近接拍攝。

Different focal length creates different effects.  But if you are using a super wide angle lens, be sure the cat lets you come as close as a few cm.  On the other hand, you need to take into account whether the space inside a house be large enough for using a tele lens. The cat below is taken by a 50mm lens on D700.  This standard lens is quite suitable for working inside my home for my cats.

拍特寫的話，可以用中長焦，這是用85mm在全片幅上的情況。但要留意景深，會否不足夠表現。

Use tele lens for close-up shots.  This is by a 85mm lens on a full frame camera.  You need to check whether the dof is enough for you to put the interest part of the cat in.

用135mm拍的話，可以離開遠一點工作，對不熟悉的貓兒比較合適。

Use 135mm lens when you need to work at a greater distance to help the cat to feel more easy.

當然，你可能有特殊視覺效果需要，這是用14mm在D70上拍的，相當於21mm的效果，工作很接近，但可以做出你所需要的效果。

When you need a very special effect, you may consider using a super wide lens.  This is done by a 14mm lens on D70 (equivalent to 21mm in full frame camera).

燈光方面，盡量用自然光，否則貓眼會因閃光而不自然，出現紅/綠眼睛或合上眼；如非打燈不可，試離機引閃，效果會好一點。利用窗戶提供眼神光是一個好辦法。用燈引閃的效果﹝指N牌的CLS﹞機頂引閃的光已足以令貓兒合上眼睛。 自然光加貓向著窗戶創造眼神光。

Use natural light if possible.  Flash will make the eye of the cat looks strange like looks green/red or closed.  If flash is a must, try put the flash unit away from the camera.  If the CLS system of Nikon is used, the commander camera flash will make the cats close their eyes. The picture below shows the effect of using natural light while the reflection of the window makes there a bright spot in the eye.

引閃的光已令她合上眼睛。

The commander flash closes the cat's eyes

戶外的光最好。

If possible, use natural light.

貓一般比狗難拍點，主因是一怕陌生人二沒像狗的聽話，所以要拍好的話要多點耐性，不是可以短時間跟他們混熟，所以除了拍靜態的照片外，可以找點逗貓棒之類跟他們玩，順便拍動能的照片。 用玩具拍動態照片：這個玩具可以讓貓自己獨個兒玩，讓你自己專心拍，不過我家雜物太多，拍這些動態的相片，背景難以控制。

Cats can be more difficult to photo than dogs.  One reason is that they are not so trained to obey commands and the other reason is that they are afraid of strangers.  Great level of patient is needed.  So, you've better find some cat toys to play with them and try to take pictures when they are playing. The following picture shows my cat who is playing.  This is a toy that the cat can play by itself.  So you are free to take his picture.  As the cat moves everywhere, you can hardly control the background.

這是放手讓貓兒跳起時影的，可以說是擺拍，但勝在一個人可以完成，拍這個我選用廣角自動對焦，亦可以用泛焦讓成功率增加。 俯角可以稍稍避開雜亂的家中雜物。

This picture is taken when I drop the toy for the cat.  I can do it all by myself alone without anyone helping me.  To make the picture easier to take, I use a wide angle lens, AF.  Hypofocusing technique may be employed too. Choosing a looking down angle will make the background clear from the things in my home.

讓貓兒們自己玩耍時抓拍也是一個好主意，有不錯的動態

You can also make snap shots while cats are playing by themselves.  This usually gives photos full of energy.

還有用光可以更大膽一點，令你的作品更與別不同

May be you can employ more creative lighting to make your picture unique.

最後，找點道具與貓兒一起拍攝也是很好的點子

Finally you can use anything at your home to give the picture a special feeling.

我家生物多樣化

住在新界邊遠地方，肯定是少見人的地方，可是，人是不多，卻不是沒有其他生物，下面這些是常見的，大概見怪不怪了：

1. 飛蛾 ─ 這些多數晚上出來活動的生物是最易入鏡的了，因為活動能力不高
   
   
2. 牛 ─ 這些被遺棄的生物，幸好還有寬大的郊野公園供他們生活
   
   
3. 蛙類動物 ─ 這些小東西也幾常伴我左右，不過入冬就小見了
   
   
4. 猴子 ─ 這些人類的近親近來經常在這一帶出沒，幸好未做成太大滋擾
   
   
5. 海邊生物小蟹 ─ 這小生物每年總有點時間會跑到山上來探訪我們
   
   
6. 蛇 ─ 總不想碰上他們，因為不小心的話會被咬的，他們也不幸，總會死在車輪下呀。
   
   
7. 石龍子 ─ 噢，不要跑進屋內，貓兒不會放過你們呢。
   
   
8. 蝴蝶 ─ 這裡有許多品種，是賞蝶的好地方呀
   
   

實在是說不完的，不過，近日多了點生物，有南來的白鷺，還有....

• 你說這是什麼呢？
  
  
  
  ﹝箭豬？﹞
• 這可不是走失的家豬呀
  
  
• 還有這些怎麼不吃草的牛牛