yes, "q" is almost fixed, a very "simple"choice by manuf. based on focLeng. I'm just blabbing offhand, haven't dabble w/ details for decades. good that u, mr.siu, exist . one more person knowing sth more. 1979 ? 44
Smartphone always has a greater depth of field because of its shorter focal length. However in iPhone portrait mode, it can give out shadow depth of field. I believe it uses computer software to achieve it. Am I right ? Thanks!
different optical companies have their own acceptable circle of confusion, for most these days they have come to almost same "standard", i think. Note : depth of field NOT = depth of focus !!!! For close focus (distance) near : far field is (say about ,safe from attacks ) 1:1 Far field increases (i.e. far depth deepens) as focus distance increases (i.e. u r stepping back or equivalent ) to about 1:2 {to be exact find out yourself} @same f/stop, doesn't matter what focal length (i.e. lens) u use, for SAME image magnification (on film or what not, my reservation on whatnot bcs i am not sure i know enough; but still it's image by lens ) the DIF is SAME for ALL lenses. try it. Does not matter whether u r a senior or junior photographer, optical law rules all.
all the different effects u see on using diff. lenses at diff. distances for PRACTICAL photography are Pleasant "deviation" from the above "unpleasant" observation. No offence to anybody, seniors in particular. Happy new year of photos. p.s. FB would ban me again? the truth?
伍sir 講解好清楚，易明
感謝伍Sir用心教導🙏
謝謝伍Sir分享！又上了一個重温課❤
😊多謝伍SIR 🎉🎉
謝謝伍SIR,温故知新,我自己影相都幾十年,景深呢家野由燒菲林年代就交晒學費,估唔到今時今日重有人會咁諗,希望你長命百歲多多提點,尤其班器材控
謝謝伍Sir，長知識了🙏🏻
伍 sir 講解得十分清楚👍
其實景深範圍(景物清晰範圍)係有一個數學公式的，叫「景深公式」，推導呢條公式十分複雜，當然呢度唔係數學 TH-cam 教學，所以不會討論。
在呢條景深公式中，只包含光圈值 F，焦距 f，拍攝距離 L，以及鏡頭彌散圈直徑 q，根據呢條景深公式，就知道景深範圍只同光圈值，焦距，拍攝距離，以及鏡頭彌散圈直徑有關，同其他咩像素啊，觀賞距離啊，放大率啊……等等完全無關，和片幅大小都無關。
數學公式就係定律，冇得呃人嘅，只係好多好多玩攝影嘅人，不太了解，或者根本唔知道有一條景深公式。
就算對於一位本身係學數學，而又冇玩攝影嘅人嚟講，一睇到呢條景深公式，都知道景深範圍同焦距 f，光圈值 F，拍攝距 L 有關，同其他嘢冇關，因為在呢條公式中，只有 F, f, L , q 呢四個參數，而沒有其他參數。呢四個參數( F, f, L, q)只要有其中一個改變，就會令景深範圍改變。
Thanks
yes, "q" is almost fixed, a very "simple"choice by manuf. based on focLeng.
I'm just blabbing offhand, haven't dabble w/ details for decades.
good that u, mr.siu, exist . one more person knowing sth more.
1979 ? 44
始終相機嘅鏡頭光學就係物理學嘅應用，而物理學都係要用公式去計數。所以景深都係要用一條公式去計出嚟，佢係有一個客觀嘅標準。
所以曾有人為了讓人明白深度，叫人改用厚度來理解深度。
另外，在這三個條件相互作用下，影像放大率愈大，景深愈淺(愈薄)
多謝伍Sir
雖然係基本嘢，但仍有很多人未搞清楚。
多謝伍Sir 簡單清晰的講解。👍🙏
😅如果嗰啲人想不清楚，幾時都是不清楚
現在很多人用手機拍照，但總不明白手機長焦為何達不到淺景深，影深是算鏡頭原焦距，不是等效焦距，手機想淺景深祇能求人像模式的假淺景深
咪就係囉。嗰啲本身完全冇玩開相機，只用手機影相嘅人，根本不明白咩叫實際焦距和等效焦距，更加不明白景深嘅原理。
最搞笑係嗰啲只用手機拍攝嘅人，仲話可以拍攝出媲美相機嘅淺景深，真係笑死人。佢哋口話所講嘅「手機都可以拍攝出媲美相機嘅淺景深」，只係依靠軟件 AI 整出來的，根本不是真正意義上嘅淺景深。
謝謝、伍Sir
謝！很清楚！
Not 4R as standard?
請問相機繩是否送完？
繼續送，供應商好捨得
伍Sir解釋得非常清楚👍👍👍👍👍，如果要全部都淸楚，就用移動對焦影幾張啦😂
多謝伍sir❤ 老蛙10mm 都想入手，正啊
多謝伍sir,一直唔明個個張相都唔同大細,廠商點定景深尺
我想睇伍sir講下呢支鏡運用在什麼地方拍攝，真係大廣除咗拍大形建築物真係好小用到，我有老蛙10 18同15 2但10呢個焦距真係不太常用到（我吾係影星的）。
伍sir好嘢勁呀，，小弟去旺角星際找不到現貨，老娃10mm 2.8😊請問伍sir去哪兒有。。多謝
Wao! Nice!
Smartphone always has a greater depth of field because of its shorter focal length. However in iPhone portrait mode, it can give out shadow depth of field. I believe it uses computer software to achieve it. Am I right ? Thanks!
正確
Thanks!@@alexngphoto
Thanks 伍sir 但記憶伍sir 亦曾說過現今科技世代用自動如P或A mode 所有曝光事宜交給相機處理.....這就是沒有或不足基礎訓練下的結果 亦相信雖然伍sir今日講得好清楚 但不足基礎者都是聽到似是如非 轉身忘記的
謝謝了
沒有中文翻譯 很可惜！
thx
学攝影一定要明白。
伍Sir功力深厚呀😅
你好伍SIR, 我前兩日報左你個 course 並交左錢, send 左 confirmation screenshot 去你 WhatsApp 但到而家都未有回應, 你可以跟進下嗎?
Ok, thanks
哈哈，对景深这个概念有疑惑的朋友，建议读一下物理学的“小孔成像原理”就清楚了，自相机诞生以来近2百年以然而依据这个原理，改进的只是感光材料，镜头和快门的设计
小小愚見，景深用深淺區分，比用闊淺區分，可以避免部分新手誤會，縱使講「深景深」有時會感覺累贅
你的建議 很有建設性， 但係景深用闊同窄去形容係一個傳統。
Wide vs Narrow is not equal to Deep vs Shallow
景深的深淺, 拍十多幅不同焦距, 不同光圈, 再用個 軟件, Helicon Focus, 加疊, 任你玩深淺景深, 亦可由近到遠都咁 sharp, 哈哈, 駛乜理 10mm 定 80mm呀。 認為層次或景深不足, 咪影立體相。立體相影要靚, 用兩部48MP啦, 唔駛要高級機架, 國産百幾二百元一部, 包靚過你名厰機呢, 哈哈
thanks
英文叫 Focus stacking, 網上很多地方有教, 而光圈重疊 HDR, 有些機有, 但自拍多幅不同光圈, 比機預設好@@alexngphoto
different optical companies have their own acceptable circle of confusion, for most these days they have come to almost same "standard", i think.
Note : depth of field NOT = depth of focus !!!!
For close focus (distance) near : far field is (say about ,safe from attacks ) 1:1
Far field increases (i.e. far depth deepens) as focus distance increases (i.e. u r stepping back or equivalent ) to about 1:2 {to be exact find out yourself}
@same f/stop, doesn't matter what focal length (i.e. lens) u use, for SAME image magnification (on film or what not, my reservation on whatnot bcs i am not sure i know enough; but still it's image by lens ) the DIF is SAME for ALL lenses. try it.
Does not matter whether u r a senior or junior photographer, optical law rules all.
all the different effects u see on using diff. lenses at diff. distances for PRACTICAL photography are Pleasant "deviation" from the above "unpleasant"
observation. No offence to anybody, seniors in particular.
Happy new year of photos.
p.s. FB would ban me again? the truth?
唔好意思呀伍Sir
不如影出來做出、唔好得個講字
作為聽力障礙人士，有字幕更好！完全聽唔到你表達啲乜，只能夠估！·
抱歉我實在太忙沒有時間做中文字幕
😂 我聽你講
膠攝現場
這段 景深我即刻內心笑一下，對唔住 😅
我都 開聲講兩句， 如果用4x5相機 ,用磨砂玻璃 ,怎樣收景深完全清楚見到.
唔關數碼 像素 問題😢
如果需要詳談的話
伍sir 我可以 示範 畀你😂
假如用 4X5？唔好講中幅啦！都唔知你想表達 D 乜野，不如講埋 8x10 啦！對焦用 loupe 睇添，你講緊傳統菲林機？你寫到用磨沙玻璃，我估你想講用傳統菲林機，響觀景器入面睇到景深清唔清楚，就要部機身有景深預示功能 (可控制鏡頭光圈實時收細/擴大)，同時對焦片有高透光量就較為容易睇得清楚。
完全 明白 , 因為今早趕返工未能詳細講述, 多謝詳細 內容 @@adktk
除左伍SIR三个因素，景深同画幅有关，同一支镜头唔同sensor尺寸，景深唔同。
期待你嘅示範，仲可以一齊食一餐飯！
你肯定冇 聽清楚我講啲乜嘢。
插、插、插😂
多謝伍sir❤
多謝伍sir🙏🏻
多謝伍Sir
多謝伍sir