F5.6= dept???

oakfieldphotography.com

Hi everyone, i hope you all can help me here.
Before i ask the questione remember that i am of an age when learning something new takes several attempts and non use of theory. Ok here we go.
I recently bought a canon nifty fifty 1,8. I am getting some great shots and unreal video footage from this lens eventhough its the baby in the bunch. What i want to know is when i choose a F stop what measurement (roughly) have i in focus at F5.6 or F1.8 or has this to do with distance from your subject matter?
Now please dont thrash me within an inch of my life if this is mentioned on this website somewhere else as i tried the search option but cant come up with any information.

Regards
Patrick.:D

Richard

Focus and depth of field are distinct. All autofocus lenses will obtain their focus wide open, regardless of the aperture setting. They will close down the aperture when you press the shutter release. So you are focusing at 1.8. The depth of field changes with the distance to your subject (the closer, the narrower) and with the f stop (the greater the number, the more DOF). Your camera probably has a DOF preview button on it, which will temporarily close the aperture to the f stop you have selected and let you see the DOF in the viewfinder. It takes some getting used to--since it is closing the aperture the image in the viewfinder becomes darker. With practice, you can learn to spot the changes in DOF despite the darker view.

HTH.

ziggy53

Larger f-stop openings, like f1.8, have very shallow DOF, meaning that you need to be very selective upon your choice of prime focus. For people and animals it is generally best to select focus upon an eye and it is best to choose a single AF point closest to the subject in the scene composition. Try not to "focus and recompose", especially at close proximity, as this can induce focus error.

At smaller f-stops you have more DOF. If this is your intent remember that there is a little more DOF behind the subject than before the subject. There is a common misconception that the DOF is split to 33% before the subject and 66% behind the subject. The truth is that the relationship varies with AOV/focal length and distance to subject.

For a good "feel" for how DOF affects particular lens/camera/distance combinations, refer to this site:

http://www.dofmaster.com/dofjs.html

oakfieldphotography.com

Thanks Richard for your quick reply.
I thought that if i could judge the distance between my camera and its subject i could choose the dept of field by looking at the subject and its background to deliberatly set what i want in focus.
I dont know how to explain this in any other way than i will have more control of what i want in focus around and in front and behind my subject.
I know i could press the dof button but there is only so much you can see through the view finder.
Is there a theory on this? Mabey a table i could follow?

Regarda
Patrick.:D

Richard

oakfieldphotography.com wrote: »

Is there a theory on this? Mabey a table i could follow

Check out the link Ziggy posted.

oakfieldphotography.com

ziggy53 wrote: »

Larger f-stop openings, like f1.8, have very shallow DOF, meaning that you need to be very selective upon your choice of prime focus. For people and animals it is generally best to select focus upon an eye and it is best to choose a single AF point closest to the subject in the scene composition. Try not to "focus and recompose", especially at close proximity, as this can induce focus error.

At smaller f-stops you have more DOF. If this is your intent remember that there is a little more DOF behind the subject than before the subject. There is a common misconception that the DOF is split to 33% before the subject and 66% behind the subject. The truth is that the relationship varies with AOV/focal length and distance to subject.

For a good "feel" for how DOF affects particular lens/camera/distance combinations, refer to this site:

http://www.dofmaster.com/dofjs.html

Exactly what i was looking for. Thanks again Ziggy53.

Regards Patrick:D

Brett1000

ziggy53 wrote: »

At smaller f-stops you have more DOF. If this is your intent remember that there is a little more DOF behind the subject than before the subject. There is a common misconception that the DOF is split to 33% before the subject and 66% behind the subject. The truth is that the relationship varies with AOV/focal length and distance to subject.

For a good "feel" for how DOF affects particular lens/camera/distance combinations, refer to this site:

http://www.dofmaster.com/dofjs.html

there are also APPS for that! - iPhone, Android, etc.