hi,
i am sure everyone knows this but i thought it would be good to
post this for those coming from the autofocus world.
Here's a method for ensuring that objects are sharply
focused without actually having to refocus everytime an
object moves.
Answer: Depth of Field & Hyperfocal distance.
This is very suitable to street shooting, where objects are always
on the move, and yet, there is a range of distances
where the objects are.
Here's an example, say you decide on f8 aperture,
and you spot a subject at 3m out. Most of us will
adjust the focus ring and twitch it around until the
rangefinder patch is aligned.
here how it looks like on most rf lens.
here's an explanation. the white box shows:
8, that's the aperture.
3, that's the distance in metres.
the pink box shows alot of details too,
the low ring does the DOF markers, "16 11 8 | 4 2 * 2 4 | 8 11 16"
The aperture chosen is f8, looking at the distance scale
above the DOF market( f8 on the left and right of the DOF marker), shows
that at f8, the distance that is in focus is about 1.75m to 10m.
So basically, at f8, and the lens is focused is at 3m, anything from
1.75m to 10m is also in focus.
Here's another example, say the object is at infinity, say 20m out.
focusing on the lens, produces something like this:
this tells us that at f8, if the lens is focused at infinity (centre),
the closest focus is 4m ( the left DOF marker f8, between 3-5m)
ie. anything from 4m to Infinity is also in focus.
A better way to achieve the last example would be to use
hyperfocal distance to focus:
I put the aperture on f8.
Next I put the infinity marker on the focus ring to rest
ontop of the f8 on the DOF marker (see yellow ring).
On the left side, the closest focus is around 2.2-2.4m
this means that when I focus this way, at f8, anything from
2.2/2.4m all the way to infinity is in focus. which is a tighter
focus than the previous example where it is 4m onwards.
At the most extreme, if i put the aperture at f16, and put the
infinity marker on the rightmost f16 mark on the dof market,
then anything from 1.1/1.2m to infinity is in focus.
of course, at f8 or f16, the corresponding shutter speed
will have to be adjusted as well.
cheers!
raytoei
i am sure everyone knows this but i thought it would be good to
post this for those coming from the autofocus world.
Here's a method for ensuring that objects are sharply
focused without actually having to refocus everytime an
object moves.
Answer: Depth of Field & Hyperfocal distance.
This is very suitable to street shooting, where objects are always
on the move, and yet, there is a range of distances
where the objects are.
Here's an example, say you decide on f8 aperture,
and you spot a subject at 3m out. Most of us will
adjust the focus ring and twitch it around until the
rangefinder patch is aligned.
here how it looks like on most rf lens.
here's an explanation. the white box shows:
8, that's the aperture.
3, that's the distance in metres.
the pink box shows alot of details too,
the low ring does the DOF markers, "16 11 8 | 4 2 * 2 4 | 8 11 16"
The aperture chosen is f8, looking at the distance scale
above the DOF market( f8 on the left and right of the DOF marker), shows
that at f8, the distance that is in focus is about 1.75m to 10m.
So basically, at f8, and the lens is focused is at 3m, anything from
1.75m to 10m is also in focus.
Here's another example, say the object is at infinity, say 20m out.
focusing on the lens, produces something like this:
this tells us that at f8, if the lens is focused at infinity (centre),
the closest focus is 4m ( the left DOF marker f8, between 3-5m)
ie. anything from 4m to Infinity is also in focus.
A better way to achieve the last example would be to use
hyperfocal distance to focus:
I put the aperture on f8.
Next I put the infinity marker on the focus ring to rest
ontop of the f8 on the DOF marker (see yellow ring).
On the left side, the closest focus is around 2.2-2.4m
this means that when I focus this way, at f8, anything from
2.2/2.4m all the way to infinity is in focus. which is a tighter
focus than the previous example where it is 4m onwards.
At the most extreme, if i put the aperture at f16, and put the
infinity marker on the rightmost f16 mark on the dof market,
then anything from 1.1/1.2m to infinity is in focus.
of course, at f8 or f16, the corresponding shutter speed
will have to be adjusted as well.
cheers!
raytoei
