"X" / On Zone Focusing

Another non-finder snap by P&S DC. Since I am doing a lot of non-finder street quick snap, the focusing speed of the DC is very important. I was and still using the Fujifilm F10, and the response time is quite good.

For non finder snaps, the old masters will use zone focusing (or pre-focusing), ie. use relative small aperture eg. f/8, and pre-focus the lens to something like 3 or 4 meters, and most common subject will fall into the depth-of-field...... It sounds complicated, but it's actually very simple and basic photographic skill. This technique is getting lesser attentions, and I guess there are a few reasons behinds:
- Modern cameras have very fast and reliable AF system, so there is no need for zone-focusing (sorry for Pentax, the K20D + DA21 combo sometimes let me down in non-finder shots).
- The depth-of-field idea is actually an approximation: ie. the photo will 'looks' sharp for 'reasonable' viewing distance. Reasonable means you are looking at a 4R photo at around 25cm distance. So if you scale-up your photo 100% on screen, it's not sharp at all. Too bad most people do zoom-up on in computer to closely look at the photos, and zone focusing just don't work for this kind of critical scrutinization.
- MOST IMPORTANT REASON: most modern lenses do not have a depth-of-field scale... so there is no way to use the lenses for zone-focusing.

What are you looking for? / On Cross Processing

With the new Aperture 3, there is a lot of different 'presets' of common digital effect, Selinium tone is one, and this one is Cross Processing. Aperture will show a quick thumbnail preview of the effect when you mouse-over on different presets, so you will know how the image will look like before clicking on it. It's real fun!

This Cross Process effect (there are two different cross process presets in Aperture 3) resembles the E-to-C effect in the film age. "E" refers to E6, which is the Kodak process for color reversal slide films; and "C" refers to C41, the Kodak process for color negative films. People actually get this idea by accident: some people mistakenly used the C41 to process color reversal slide, and they find the processed slide to be of high contrasted and mis-colored. Some people like the surreal feeling, and intentionally use E-to-C as a creative tool of photography.

It's the old days. Now we have digital processing, and you don't need to know a lot about technical to try different color effect. Many new programs also have this kind of effect build-in, so all you need to do is one mouse click. HOW GOOD IT THAT!!

An off-finder street snap with wide angle, cropped and leveled. "Cross Process1" effect in Aperture.

"Passed by...." / On Selinium Toner

An old snap with slide (yes, the expensive slide). This shot was shot on ISO100 slide, handheld at approx. 1/4s, scanned with film scanner, and digitally altered to monochrome with Selinium tone.

Speaking of Selinium tone, it is actually more than an artistic style.

In the good old days of black-and-white photography, the photo paper was treated with chemicals. Because of the acidic nature of the 'fixing' process, b/w photos are prone to color fading over time, particular when photos are not washed in running water long enough. For additional stability of the photo-print, an additional step called 'toning' is often used. Most toner will alter the color of the print, e.g. Sepia Toner will add a brown tone to the print. Selinium Toner is the most stable toning chemical, and often used in gallery display.

The depth-of-field myth on APS-DSLR

A common question: "how does the depth-of-field on 1.5X crop factor (APS size) compare to full-frame film?"

I don't want to go into the theoretical and mathematical details of depth-of-field. So I will use a Palm program to solve this. The circle-of-confusion used by the program is 30um for full-frame, and 25um for APS-DSLR.

In short, the DOF is affected by: focal length, shooting distance, aperture, and film (sensor) format. So the above question is a tricky question because it has 2 different answer. The DOF on 1.5X DSLR is bigger then 135 full-frame, and it's also smaller. It all depends on how you look at the question.

First, if you are using 'equivalent' lens on your DSLR, shooting at the same position, using the same aperture.... the DOF on DSLR is greater than full-frame film. eg:
full-frame: 75mm lens, f/2, distance=2m
APS-DSLR: 50mm lens, f/2, distance=2m
You will get the same framing and perspective with the above 2 setting. But the DOF with APS-DSLR will be bigger than full-frame 135:
DOF of full-frame: 1.96m to 2.04m, ie. 8cm
DOF of APS-DSLR: 1.92m to 2.08m, ie. 16cm

So, many people say full-frame has more 3D feeling than APS-DSLR. The main reason it the difference in DOF: a shallower DOF gives more 3D feeling.

On the other hand, if you are using SAME LENS, shooting at SAME DISTANCE, than the DOF of APS-DSLR will be shallower than full-frame 135, eg:
full-frame: 50mm, f/2, distance=2m, DOF=1.91m to 2.10m, 19cm
APS-DSLR: 50mm, f/2, distance=2m, DOF=1.92m to 2.08m, 16cm
So if you are going to use the DOF scale on your lens, the DOF on APS-DSLR will be approx. 1/4 stop shallower.

Understanding Bokeh

Here is a very clear and easy to understand webpage about bokeh.

Bokeh means the out-of-focus appearance, and it's a very important element to render the 3D feeling in a photo.

The Accidental Angle

For most photographic subjects, you have the freedom to choose from infinity numbers of moment and take the photo. In scenery photography you may choose from different weather and different times in a day. In portrait photography you may ask the model to post differently and capture the moment you think best. In wildlife photography you can choose to 'live' in wild and wait for the best moment if you wish to.

For most photographic subjects, you have the freedom to choose from infinity numbers of photographic angles. Move the camera a few inches left or right; Standing or knee down; switch to a different focal length... you can have a different view point to the subject. For some special lens or sheet films, you can also have the liberation of lens movement to alter the perspectives and DOF of the photo.

For most photographic subjects, you will also have certain degree of control on the lighting. You can choose the time-of-day for scenic photos. You can choose the shooting angle or decide to use a fill-flash in portrait. And you have the total control of lighting in studio shots.

It's all different in snap shots.

In my opinion, snap shots is to freeze the sudden moment with a photo: at that moment, at that angle, with that lighting, that everything. Since it's the photography about what's happening, it requires the photographers to have extremely fast response. You have to aim the camera, focus, control the exposure, and press the shutter. Even with modern day automatic cameras, you still have to aim and shoot.

Even thou you have practiced your skills, you still have to train you observation skill. Everything you come-across in your life is from an ACCIDENTIAL ANGLE, and you have to identify what's photo worthy.

At best, you should be able to predict what will happen, and have your cameras all readied when thing happens. In Robert Capa's Famous photo "Death of a Loyalist Soldier", he knew the poor soldier will get shot when the young soldier charged forward, BEFORE the shot in his head - according to an interiew with Robert.

It is so difficult to do snap shot, and therefore it's difficult to get a truly good snap. And that's why I am so fascinated about snap shots. I never been able to produce really good snaps, and that’s what keep pushing me to do it.

My not very successful snaps of accidential angles are here.

Golden Section / 黃金比例

note: an old article written 2 years ago, in Chinese.

在看攝影書時, 構圖一節總少不免提及黃金比例或黃金分割, 教讀者幻想畫面橫直各分三等份如九宮格, 並將主體放在幻想線的交叉點上. 但幾乎所有的攝影書都沒有進一步說明甚麼是黃金比例. 我對黃金分割的建議並不熱衷, 但看多了其他的書本, 有一點的了解, 擬文道出我所知的. 由於看的都不是科班用書, 如此文內容有錯, 請予指正.

首先, 黃金比例嚴格地說是 1:1.618; 亦可說成 0.618:1. 說成三分一, 只是為了簡化. 有龜毛的廠商對此很執著, 賓得就曾出了一個有黃金比例格線的對焦屏, 當中用的是真正的黃金比例而不是1/3.

單從上面的數字看來, 1.618 這數字夠特別, 1:1.618 = 0.618:1 = 1:(0.618+1), 即 a:b = b:(a+b), 數學上實在夠美. 這數字如 pi 一般, 是不盡的, 來源就是一個數字系列: 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, ...... 當中每一個數字都是前兩個數字之和. 當這系列一直向上, 每兩個相鄰數字的比例就是1.618! 我試用 Excel 計算, 在第 25 行以後 Excel 便投降了, 算出了的黃金比例值為 1.618033989.

確是一個特別的數字. 但很多數字如圓周率 (3.14159265358979323846264...), 自然對數 (2.718281828...) 等都很特別, 為甚麼 1.618 會被視為黃金比例? 為甚麼數字的遊戲又會跟攝影拉上關係?

那可有點邪門.

原來這樣的一個數字, 廣泛存在於自然界之內. 你肚臍到地面的距離, 跟你的身高的比例, 正是0.618. 你的前臂長度, 正是你手臂全長的 0.618 倍. 腳的長度跟手臂的情形一樣. 在很多不同的生物上, 情形也是一樣, 很多的長度比例也是 1.618是 1.618. 最出名的例子是鸚鵡螺: 那螺旋狀的螺殼相鄰的兩層的半徑比例就是 1.618. 甚至於某一些昆蟲族群中, 雌雄的比例也是 1.618.

這奇怪的現像於文藝復興時期發現, 很多的學者都醉心於這數字, 如達文西就偷了大量的屍體量度各骨骼的比例並發現很多地方都是 1.618. 但人類知其然, 卻不知其所以然, 直至今天, 人類仍不能解釋為甚麼這數字在自然界中是這樣普遍. (會不會 chaos theory 可解釋一二? 我不清楚.)

當時的人認為這數字是天上來的, 並十分推崇. 很多的藝術家, 在其作品中嚴守黃金比例, 作品包括有繪畫, 石像, 建築, 甚至音樂. 我不懂藝術, 就由懂藝術的人來舉證吧.

大抵因為自然界中普遍存在著的關係吧, 人類早習慣了看依照這個比例的東西, 故看見嚴守黃金比例的藝術品都感到舒服. 而今天的攝影書上, 亦都會認為依黃金比例構圖的作品看上去較為舒服而不呆板.