F-Stop

Examining Depth of Field.


When operating a camera manually it helps to understand this...
F-Stop = diameter of the aperture / focal length. Picture below.

F Stop e.g. f/16 setting lets in the least amount of light (small diameter) and a long depth of field
F Stop e.g. f/4 setting lets in the most light(large diameter) and a shallow depth of field


Shutter Speed = how long the actual "exposure" takes.
Because I'm changing the F Stop I also have to change the Shutter Speed to get the correct exposure.
Aside from understanding that...the depth of field is what I'm interested in.

Ok, now my test of "Depth of Field".


Here's my experiment.
Using my standard zoom lens DT 18-70mm f/3.5~5.6 up-close.


F Stop e.g. f/22 gives you a longer depth of field or in other words...a longer distance in focus.
But can't see a noticeable difference between these first two pictures with this long shot of about 60 feet.
I think it's because there are too many images in this picture.
Can you see a difference ? I can't.


Shutter speed is 25th of a second and f/22 stop/aperture



F Stop e.g. f/8 gives you a shorter/shallow depth of fields or in other words...a short/shallow distance in focus.
Shutter speed is 200th of a second and f/8 stop/aperture





BUT here you can see the difference with a shorter shot of 6 feet


Again...
F Stop e.g. f/22 gives you a longer depth of field or in other words...a longer distance in focus.
Shutter speed is 25th of a second and f/22 stop/aperture
Did not use a tripod or picture would be clearer. My camera has stability control.



Again...
F Stop e.g. f/8 gives you a shorter/shallow depth of fields or in other words...a short/shallow distance in focus.
Shutter speed is 250th of a second and f/5.6 stop/aperture



So what's my conclusion?
For landscape shots...manual is not necessary.
For close-up shots where you want the background to be blurry use a small F Stop.
Also there's always different lenses, but don't feel I have a need for that now.
Although a Macro Lens might be nice.
Still learning to use a DSLR...any suggestion/advice is welcome.

My camera info is located at the bottom of side bar.