[onjo3]

之前有聽過一個叫csmacro既師兄
分享關於zoom同prime景深 ge分別

我有一個問題:

example:
if 我用 5d (FF)+ 100mm f/2 + x1.4 = 140mm

咁我係咪仲可以做到 140 f/2.8 ge 景深 ???
or只係100mm f/2.8 ge 景深 ???

if 我用 50d (APSC)+ 100mm f/2 = 160mm
但係只可以做到100mm f/2 ge 景深, 不過張相拉近左, 對不對??

thx~

[sx813]

5d (FF)+ 100mm f/2 + x1.4 = 140mm F/2.8

50d (APSC)+ 100mm f/2 = 160mm F/2.8

[wesleyyau]

> 50d (APSC)+ 100mm f/2 = 160mm F/2.8
呢個點計 F2.8?

[Obi-Wan]

if 我用 5d (FF)+ 100mm f/2 + x1.4 = 140mm

咁我係咪仲可以做到 140 f/2.8 ge 景深 ??? <=== YES

if 我用 50d (APSC)+ 100mm f/2 = 160mm
但係只可以做到100mm f/2 ge 景深, 不過張相拉近左, 對不對?? <=== YES

[reflexboy]

Re: if 我用 50d (APSC)+ 100mm f/2 = 160mm
但係只可以做到100mm f/2 ge 景深, 不過張相拉近左, 對不對?? <=== YES＜======NO! 影像係根本無拉近到！請勿傳播錯鋙訊息！免得影響dcfever公信力！

[Obi-Wan]

reflexboy

u can disprove me by posting photos or if u like u can start a new thread & let me teach u

[reflexboy]

My point has been typed here for a few times since last year. And I'd spent enough time on you and your rubbish.
U wanted to teach me huh? Unfortunately, your credibility had dropped to a negative figure long ago! And u are surely not qualified to do so.
If u have something solid other than "<====YES/No" ! Just show it to the public. Otherwise, please keep your big mouth shut!

[reflexboy]

Speechless??? Or surfing the Internet for an answer?

[sar999]

放大 ≠ 拉近

[Obi-Wan]

High EQ ppl will not irritate low EQ ppl.

If someone says something u do not agree, the reasonable response is to show the proof what was wrong.Oth

Similarily if any brothers found obi-wan wrong, it is reasonable to ask the proof. If no proof, it's no point to discuss. I did not say I was right but if u can't show it was right, may be I was right!

I will not response to someone who does know what safety shutter speed is, while keep on bugging others.

Happy shooting!

[wesleyyau]

http://en.wikipedia.org/wiki/APS-C
哈哈... 真係唔知應該叫放大定係拉近...
用APS-C/APS-H 只係FF 中央o既成像咁去理解...好似簡單D...

[reflexboy]

Such answer is expected! And you did that a few times.
Don't act like a gentleman obi wan. You are not! You are only an uneducated coward!

Quote<<<<<<<<<<<<<<<I will not response to someone who does know what safety shutter speed is>>>>>>>

And that's why you are hiding! Good day!

[iso100000000]

讓我試試用這個方法解釋一吓:


如果用加咗1.4X增距鏡，佢係利用光學原理去改變鏡頭焦距，就等如另一支鏡頭。

例子: 假如100mm有4片玻璃(原本鏡頭)，而家再加2片玻璃(增距鏡)去將原本的光線扭曲改變為140mm的焦距，就算是不十足都有九成似一支140mm的特性。

就如兩支不同廠，而同焦段的鏡頭一樣，它的鏡片組合也不一樣，散景也各有特性，但應該是140mm應有的散景。


不會像APS-C機只是將影像裁出放大，而不是改變焦距，所以相片景深也不會改變的。

以上根據我的經驗和知識去回答，未有十足科學根據，不過我會去測試引証因我有1.4X增距鏡。

[onjo3]

anyway, i understand the truth now,
just no need to argue,
thx, both~

[SleepingIII]

影响景深的是实际焦距，而不是等效焦距。把（100mmf/2+1.4x）视为一个（而不是两个）光学结构，其实际的焦距为140mm，而且光圈值为f/2.8（因为光圈值等于实际焦距/通光孔直径）。但是50D+100mmf/2，实际焦距还是100mm，实际光圈值为f/2。
明白？