Focal length and depth of field

Focal length and depth of field

by Husam Jubran -
Number of replies: 1

Hi, 

I have a small question, we learned that "large f --> large rb", but when f is large enough, we get in both the denominator and the numerator approximately f^2 ( because the other f's in the denominator won't effect), thus, changing f doesn't have effect on rb. is that correct or am I missing out some details? 


Thanks in advance,

Husam

In reply to Husam Jubran

Re: Focal length and depth of field

by Chen Zhao -
I agree with you on this point, but I would say that in reality f can rarely be "large enough". For example rb will become larger if f is changed from 1 to 2.