More DOF Calculator b*llsh#t

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Archive 2009 · More DOF Calculator b*llsh#t

Jman13
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p.2 #1 · More DOF Calculator b*llsh#t

David Clapp wrote:
I am afraid so. If I set any of my old Cotax lenses to the hyperfocal distance claimed on the lens, the results are way out when examined at 100% in RAW.

That was my whole point: Viewing an image at 100% is the equivalent of examining like a 50" print. It is no different than with film.

Jul 31, 2009 at 03:14 PM

mawz
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p.2 #2 · More DOF Calculator b*llsh#t

jcolwell wrote:
David Clapp wrote:
...Remember that great statement "oh I just focus a third into the scene", well if your happy with that then great, but if you earn a living from imagery thats a lacklustre approach.

It's also incorrect with most lenses, see Harold Merklinger's "The INs and OUTs of Focus", at http://www.trenholm.org/hmmerk/#TIAOOF. Apparently, some lenses optimized for wide aperture portraiture do have critical focus in the forward part of the DOF, to give better background separation and blur. This is not the case for most lenses, where cricital focus is in the middle of the DOF.

Part of the issue is that DoF is not actually distributed as the 1/3-2/3 rule suggests. The math says that the distribution changes at different focal lengths and distances. Ctein had a good write-up on DoF over at <a href="http://www.theonlinephotographer.com">TOP</a> last month.

DoF scales have always been oriented towards the average user, which currently means 8x10 prints held at arm length. Until the average print size changes dramatically you won't see a change in DoF marking habits. They're never going to make DoF scales oriented towards large prints, they'd be far too pessimistic for most shooters.

Jul 31, 2009 at 03:18 PM

David Clapp
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p.2 #3 · More DOF Calculator b*llsh#t

thrice wrote:
I agree with Richard on this one, when shooting Landscape I use my 5D Mark II like a miniature view camera, assessing the horizon and the foreground until I feel there is an acceptable DOF still keeping the horizon in focus.

For you David as I know you're considering a 5D-II I will describe this in detail. I will set up the camera in front of the desired scenery, turn on MLU, 2s timer and my remote.

I then press the live view button. A rectangle appears which I move down to the nearest foreground element. I then Press the magnification button twice to get 10x magnification and if this compositional feature is in focus (set to infinity but f/11-f/16) I'll usually just take the shot.

If it isn't I'll turn the focus ring until it just comes into focus (pretty obvious in live view) then use the joystick above the rear wheel to move the area being magnified up to the horizon and I'll just double check that is still sharp, and stop down as necessary until it is. Sometimes a little more tweaking is required but this is the gist of it.

I can easily view focus at f/13 after the sun has gone down on an overcast day. I'm pedantic so after I've checked focus I'll turn off live view and wait about 10-20s to allow the sensor to cool before I fire the shutter but I doubt it makes a difference

Try this, its very similar, thats a great method by the way so thanks for letting people know -
1. Set to f16, focusing to manual
2. Engage live view
3. Move 10x square to horizon feature
4. Engage DOF preview button (this will shut the aperture down and give a hyperfocal Live View) and adjust shutter speed to get a bright view
5. Focus the lens closer to you, but keep the infinity feature in focus.
6. Release DOF preview. Now the horizon will look totally out. Press it again and it snaps back into focus.
6. You have now set the lens hyperfocally at f16 (well as accurately as you can all things considered)

I just concern myself with the horizon features and I am happy to let the foreground features go a little. It works really well. Its also totally brilliant for focusing a tilted 24mm TS-E.

BUT it still has proved to be a little troublesome for me, especially when shooting very wide. Its often hard to focus like this at 14-16mm.

Also I dont want to be checking this very often if I can help it. Moving and repositioning the camera often causes me to nudge the camera focusing without me knowing. I know once the lens is tested, I have made my charts, I dont even have to use the above method, I can just set the camera to a particular point and off I go, knowing I will have the most DOF the lens can give me hyperfocally without losing infinity focus.

Edited on Jul 31, 2009 at 03:57 PM · View previous versions

Jul 31, 2009 at 03:22 PM

Brambling
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p.2 #4 · More DOF Calculator b*llsh#t

David

I came to the same conclusion using the Zeiss or Zuiko lenses on a DsII. The solution I came up was to use half the hyperfocal distance unit for any particlar aperture. So for F16 set infinity on the F8 lens marker - try it and see if this works for you

Mike

Jul 31, 2009 at 03:30 PM

edwardkaraa
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p.2 #5 · More DOF Calculator b*llsh#t

Nothing new about that. It was always known that DOF is equally distributed for macro shots, but with distant subjects, the 1/3-2/3 rule only applies to wide angles, while telephotos behave the opposite way. Not sure about standard lenses though

mawz wrote:
jcolwell wrote:
David Clapp wrote:
...Remember that great statement "oh I just focus a third into the scene", well if your happy with that then great, but if you earn a living from imagery thats a lacklustre approach.

It's also incorrect with most lenses, see Harold Merklinger's "The INs and OUTs of Focus", at http://www.trenholm.org/hmmerk/#TIAOOF. Apparently, some lenses optimized for wide aperture portraiture do have critical focus in the forward part of the DOF, to give better background separation and blur. This is not the case for most lenses, where cricital focus is in the middle of the DOF.

Part of the issue is that DoF is not actually distributed as the 1/3-2/3 rule suggests. The math says that the distribution changes at different focal lengths and distances. Ctein had a good write-up on DoF over at <a href="http://www.theonlinephotographer.com">TOP</a> last month.

DoF scales have always been oriented towards the average user, which currently means 8x10 prints held at arm length. Until the average print size changes dramatically you won't see a change in DoF marking habits. They're never going to make DoF scales oriented towards large prints, they'd be far too pessimistic for most shooters.

Jul 31, 2009 at 04:26 PM

David Clapp
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p.2 #6 · More DOF Calculator b*llsh#t

"It was always known that DOF is equally distributed for macro shots" - I didnt know that. Cheers Ed

Jul 31, 2009 at 04:34 PM

Toothwalker
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p.2 #7 · More DOF Calculator b*llsh#t

edwardkaraa wrote:
Nothing new about that. It was always known that DOF is equally distributed for macro shots, but with distant subjects, the 1/3-2/3 rule only applies to wide angles, while telephotos behave the opposite way. Not sure about standard lenses though

It is unclear how the 1/3-2/3 myth ever got started. Any lens used at sufficiently close
focus yields a DOF distribution (front:rear) of 1:1. Any lens used at hyperfocus yields a
distribution of 1:Inf. Somewhere in between there will be a distribution of 1:2, but you'll have to look for it.

Jul 31, 2009 at 05:19 PM


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