Aperture and DOF

[Kenneth Elkington]

So I've got a question. Is DOF governed by aperture or light transmission? for example I have two lenses of the same focal length, one is f1.5 the other is f1.6 but they are both t1.8. Will they have the same DOF or different DOF?

 

[David Mullen ASC]

F-stop / aperture size determines DOF, not that there is a real practical difference between f/1.8 and f/1.6... but technically there would be less DOF at f/1.6 than at f/1.8.

 

[michael zaletel]

F-stop / aperture size determines DOF, not that there is a real practical difference between f/1.8 and f/1.6... but technically there would be less DOF at f/1.6 than at f/1.8.

Hi David:

What is the mathematical difference in depth of field between f/1.6 and f/1.8? 12.5%, 11.1% difference?

-michael zaletel
(shooter)

 

[David Mullen ASC]

I'm not sure what the practical application of figuring the percentage difference out would be. What sort of photography needs to know that? For matching CGI efx into the plate?

Math is not my strong suit anyway...

 

[Kenneth Elkington]

Thanks for the info. I've been trying to figure out this conundrum for a while.