does focusing distance matters?

[longkangman]

DOF is governed by 3 factors i) aperture, ii) distance between subject to background, iii) focal length used.

Thanks got it, I back to read basic book liao.. :lovegrin:
Foget one thing the aperture. :embrass:

 

[Artosoft]

DOF is governed by 3 factors i) aperture, ii) distance between subject to background, iii) focal length used.

Eh....,

I though DOF (Depth of Field) governed by 4 factors:
1) Lens' Aperture.
2) Distance between camera to subject.
3) Lens' Focal Length.
4) CoC (Circle of Confusion). This a bit long/difficult to explain.

Regards,
Arto.

 

[zhang3feng]

Eh....,

I though DOF (Depth of Field) governed by 4 factors:
1) Lens' Aperture.
2) Distance between camera to subject.
3) Lens' Focal Length.
4) CoC (Circle of Confusion). This a bit long/difficult to explain.

Regards,
Arto.

Hi Artosoft, kind to share what is CoC??:think:

 

[Artosoft]

Hi Artosoft, kind to share what is CoC??:think:

Google it .

Here is one for your reading pleasure:
http://en.wikipedia.org/wiki/Circle_of_confusion

Regards,
Arto.

 

[zhang3feng]

wah very chim... :sweat: but thx artosoft! :thumbsup:

 

[Artosoft]

wah very chim... :sweat: but thx artosoft! :thumbsup:

Hehehe...

Yeah... CoC (Circle of Confusion) always confuse me too :bsmilie: . But it is exist with purpose.

CoC is something like to determine how blur is blur....:bsmilie: .

Regards,
Arto.

 

[lsisaxon]

ya, after after the stated distance will be infinity..

Then it doesn't matter at all.. Some lenses are made to focus with less turn than others. If you compare Carl Zeiss ZF lenses with Nikon's you will find that the amount you have to turn is nearly a whole complete rotation. The reason given is that you can get a more accurate focus, but it's not good for press photography where you need speed... However, for today's AF, the mechaism is so accurate that it shouldn't matter at all.

 

[theRBK]

Then it doesn't matter at all.. Some lenses are made to focus with less turn than others. If you compare Carl Zeiss ZF lenses with Nikon's you will find that the amount you have to turn is nearly a whole complete rotation. The reason given is that you can get a more accurate focus, but it's not good for press photography where you need speed... However, for today's AF, the mechaism is so accurate that it shouldn't matter at all.

yeah...if you try 28-105 f3.5-4.5 focus ring, it's only like 1/4 turn...and they only mark from 0.5-2m and then infinity...no space to mark focus distance with more detail

 

[Artosoft]

yeah...if you try 28-105 f3.5-4.5 focus ring, it's only like 1/4 turn...and they only mark from 0.5-2m and then infinity...no space to mark focus distance with more detail

Maybe the lens manufacturer should put LCD to display focus distance .

Regards,
Arto.

 

[theRBK]

Maybe the lens manufacturer should put LCD to display focus distance .

Regards,
Arto.

:think: :bsmilie:

 

[yowch]

Simpler to understand CoC with ACTUAL PRINT SIZE. If you print small (say 1" x 1.5", that's really small), even a picture out-of-focus will look quite sharp. But a large print (say 2' x 3', that's poster size), even at F16, very well focused and good sharp lens, the depth-of-field may still be too narrow depending on your subject depth (thickness).

Certainly helps to buy a book (try Riceball at Adelphi) and read up on the mechanics of photography.

 

[JLLJ]

Maybe the lens manufacturer should put LCD to display focus distance .

Regards,
Arto.

Then all non-AFD lens has to retire or sell cheap bec no kick if your focus distance LCD show ??? with non-D lens.