Hyperfocal Distance Question

[Robbo7D]

My depth of field calculator tells me that if I take a photo of an object (lets say a landscape) & that object is approx 200M away, (I use a Canon 7D with f-stop at 10 & focal length at 15mm) that my hyperfocal distance is at 1.2 M. So if I focus at 1.2M, then from 0.6m to infinity should be in focus. Does that sound correct?? I have been reading about focusing somewhere 2/3rds of the distance to the object to get sharp pictures. 1.2M away? That sounds too close! Peoples thoughts please.....

[ameerat42]

The 2nd bit sounds optimistic, Robbo. The closest I can approach your figures is with my shortest lens, an f=28mm:

Subject distance "infinity"
f=28mm
f/11
Hyperf approx: 1.2m to infinity.

Subject distance 1.2 m
f=28mm
f/11
Hyperf range approx: 0.8m to 2m

Did you post a link to this calculator in any other thread?
Am.

[ameerat42]

Well, I might have to eat a hat. I just found THIS HFD calculator and approximated your settings.
Here's the result... (Screen print from http://www.nikonians.org/html/resour...erfocal2.html0 )

[Robbo7D]

The 2nd bit sounds optimistic, Robbo. The closest I can approach your figures is with my shortest lens, an f=28mm:

Subject distance "infinity"
f=28mm
f/11
Hyperf approx: 1.2m to infinity.

Subject distance 1.2 m
f=28mm
f/11
Hyperf range approx: 0.8m to 2m

Did you post a link to this calculator in any other thread?
Am.

Ameerat42,

Calculator is an app for my Android phone. I have used a focal length of 30mm in this example. (please note that subject is 5000 M (infinity)

Subject distance: 5000 M (infinity)
f=30mm
f/11

hyperf distance= 4.34m

So if I focus 4.34 M away I should have sharpness from 2.17m to infinity. Agree?

[kiwi]

id always focus on something 2/3 into the frame personally

[Robbo7D]

Thanks Guys,

Gives me a good opportunity to experiment & get out there & test some theories.

[ameerat42]

While I was "calculating" with my f=28mm lens.... Yes, it would seem to be right, but I'd try some actual shots.
Here are my "test results"...
Am.

[OzzieTraveller]

G'day Neil [& AM]

Your original thoughts are pretty close ...

Firstly one of many standard optical definitions - "infinity" for a camera lens is taken as being 1000 times the focal length
Focus is deemed to be "in-" or "out-of" when the so-called "Circle-of-confusion" becomes "unclear" [but don't let this worry you]

Hyperfocal Distance [HD] can be calculated [as per AM's diagrams], and comes closer to the camera position as the lens is stopped down
If you focus upon the Hyperfocal Distance, then your Depth-of-Field is exactly half the distance between the camera and the HD thru to infinity

Thus - looking at it in reverse - DoF is 1/3 before the point of focus and 2/3 behind the point of focus

Hope this helps [or at least adds to your level of confusion]
Regards, Phil