It seems to me that on my Canon T3i, the sharpest I can get image is at f8. But even at f8, not everything is in focus and you have to pick and choose. I am guessing to get more in focus I have to close the aperture more. But going beyond f8 leads to aperture diffraction, so that also puts the image out of focus as well. I can't seem to find a hyperfocal sweet spot, between f8 and diffraction. Any thoughts? Thanks.
Question about shooting hyperfocal.
- Thread starter ironpony
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At that point, you really have to pick and choose. The best that you can probably do is at F/8 (which may or may not be the sweet spot depending on the lens), and place the focus to a nice spot, maybe where ever infinity just becomes in focus. That way, you have the widest range of things within the depth of field you're given.
Leon Bailey
Well-known member
Yeah, the sweet spot depends on the lens I believe. What lens are you using?
stefancolson
Well-known member
Use your lens as wide as possible at the focus plane will increase in size. You'll get a lot closer to holding everything in focus at 18mm than you will at 55mm. f/8 @ 18mm should be everything from a few feet out to infinity in focus.
Okay thanks. That makes sense, as to some of my video results. What if I am on a rooftop though, and I want to frame the view of the buildings in a way though in which I need to go to say 35mm or further longer than 18 at least? Is there a formula I should do as to what the aperture should be at different focal lengths?
j1clark@ucsd.edu
Veteran
The Hyperfocal distance is based on lens length, aperture (f-stop), and the circle of confusion based on a given enlargement/viewing size.
The wiki gives two definitions:
1) Definition 1: The hyperfocal distance is the closest distance at which a lens can be focused while keeping objects at infinity acceptably sharp. When the lens is focused at this distance, all objects at distances from half of the hyperfocal distance out to infinity will be acceptably sharp.
2) Definition 2: The hyperfocal distance is the distance beyond which all objects are acceptably sharp, for a lens focused at infinity.
Therefore the Hyperfocal distance will change given changes in f-stop and focal length and viewing size...
I would suggest getting either these iPhone Apps, as both give the Hyperfocal distance for various camers, with various lens lengths and f-stops...
http://www.chemicalwedding.tv/toland.html
http://www.davideubank.com/Good_Focus/pCAM_Film+Digital_Calculator.html
For example using my GH-1... with my 'zoom lens' at 25mm (these sorts of things are approximate, as the markings on the lens could be in error... both in focal length and/or f-stop...).
Lens focal length: 25mm
Lens f-stop: f/8
From the above mentioned Toland iPhone App:
Hyperfocal distance (Principle Focus plane): 17' 1" (get out your measuring tape... that's why you see it being used on BTS segements on the DVD/BD disks... they are making sure the principle plane of focus is exactly where the actors are going to be, and that any movement on the actors part will be in the 'Depth of Field' for the given lens settings.)
From the above mentioned pCam iPhone App:
Hyperfocal distance: 17' 2"
So within a small tolerance... the same...
Both of these Apps calculate the 'principle plane of sharp focus', which is 17' 1-2" depending. Using definition 1, both calculate that objects falling between 8' 7" on the near side, and things receding into the 'infinite' distance on the far side of that principle plan, would be in 'focus' for the given Depth of Field.
If your object is closer than 8 feet, it will become 'blurrier' depending on how close it may be to the camera.
stefancolson
Well-known member
Great info from j1clark as usual. There's also a web-based app that will do DOF calculations: http://www.dofmaster.com/dofjs.html
Moseph
Veteran
Kodak also has a great iPhone app that does the same thing, among other things.
Okay thanks, that helps a lot. It seems when I am shooting a scene with actors though, that you still need to pull focus on f8, if an actor moves more than say a foot or less. How come it's that way on f8 at an 18mm wide shot, but when getting landscape establishing shots, it comes out much more hyperfocal? Or at least this is what I saw a camera man doing while shooting a scene I helped with.
j1clark@ucsd.edu
Veteran
I don't know what the phrase "it comes out much more hyperfocal"... means...
The Hyperfocal distance relates to Depth of Field and 'acceptable sharpness' or 'acceptable fuzz' if you will. It does not change the plane at which the lens is focused for 'sharp' focus. To account for movement of the actors focus will still be 'pulled' if critical focus on them is required.
stefancolson
Well-known member
The depth of the focus plane is (in part) determined by the subject's distance from the lens. If you try to shoot someone 4' away, even at f8 on your lens at 18mm, you're going to get a much shallower plane of focus than if the person was standing 10' away. That's why you can get big swaths of landscape in focus with a more open aperture than you can actors at closer distances.
What I mean is, is that it comes out much more sharp. I figure if I can get a whole landscape looking sharp, then why not a whole scene with actors in different places of the room. But I guess they need to be further, which is what I guessed might be the case. Thanks.
j1clark@ucsd.edu
Veteran
Think of it this way... if one is shooting a subject with sharp focus at 8'... and they move 4 feet... either way... they have moved a significant amount... if the plane of sharp focus is 600 feet out. and the subjects move from 596 to 608 feet... not much of a change...