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 KZbin 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。
@alexngphoto8 ай бұрын
Thanks
@user-pg5rt7ju4f8 ай бұрын
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.
@user-pg5rt7ju4f8 ай бұрын
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?