What is meant by F/# of 2.0 or F/2.0 of lens?
While selecting lens for an omnivision image sensor, I have to meet one requirement from customer which is confusing that is,
"Requirement of f/# of 2.0"
We know f/# means Focal_length/Focal_number, which is the measure of aperture diameter. My question is
1. How f/# influence lens selection?
2. What happens if it is fixed to f/2.0? Means, can I say this much area will be focused?
3. what happens if I fixed to any other aperture diameter f/2.8, f/4.. etc. ?
Thanks in advance..
F-Number affects speed and depth of field. Try a Google search. You can do it!
Yeah that I know. I have searched more about it.
In the case of camera lenses we have option to change to our desired f/#. But while on boards (phones, other camera application electronic boards) we use a single f/# and my question is how we can fix it to a single value?
we can say f/2.0 and f/1.8 both have relatively almost same depth of field right? can we quantify it?
It also depends on focal length. Use a depth of field calculator.
Hi Volker,
Thanks for the info. But why most smartphones use F/1.7 F/2.0 F/2.2 these ranges only? why dont they choose higher F-number? I think there is a reason for that...
larger F#= slower speed, i.e., you need more exposure time (or more light).
Why not read a bit about specification of recent smart phone cameras?
None of it has variable aperture, thus camera lens f-number is designed for highest possible sensitivity with useful depth of focus. Most smart phone cameras have fixed focus, only a few, e.g. Samsung S8 have variable focus.
I know it is fixed. I specified these f/# of different smart phones. redmi have F/2.0, samsung F/1.7 etc..
This is my question, can we quantify it?. one thing is DOF calculator, which is also depending on camera manufacturer..
WHAT is your question? You keep saying you understand about f# and then you ask questions seeming to indicate that you actually DON'T understand. Depth of field does NOT depend on camera manufacturer. It is not a hard constant, as you need to define what is considered "in focus" and what is not, i.e.'acceptable circle of confusion'.
Exactly, and in the DOF master online calculator we can choose the 'acceptable circle of confusion' in the dropdown list, at the end of the list.
@vishnuk, if you don't know what number to use, maybe the CoC calculator at the bottom of the page can help
http://www.dofmaster.com/digital_coc.html
but as barry wrote, it's only some estimate of what looks "sharp enough".
Hi,
Thanks for the info barry and volker. Let me read more about COC.