Focus-Recompse: Can I get your thoughts?

Discussion in 'Beyond the Basics' started by MarcusM, Jun 12, 2008.

  1. MarcusM

    MarcusM TPF Noob!

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    What are your thoughts on "Focus/Recompose" where you lock the focus, normally with the center AF point, on the part of the shot you want to be in focus, and then you recompose to achieve the desired framing?

    I got in this habit of doing this all the time since learning it in my photography class at tech school (back in 1997, before digital cameras were commonplace)

    I read this article recently and I am wondering if this is the reason for a lot of my shots that come out slightly soft?
    http://www.outbackphoto.com/workshop/phototechnique/essay06/essay.html

    The problem with using the other AF points is that often times they don't allow me to compose the shot as I desire - especially since my 300D doesn't have AF points located on all the "rule of thirds" points, although I have been using the other AF points more often now than in the past.
     
  2. JIP

    JIP No longer a newbie, moving up!

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    Why not just use manual focus??
     
  3. MarcusM

    MarcusM TPF Noob!

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    I don't really like the manual focus of today's cameras - it is too hard to tell when it is perfectly in focus, compared to the manual focusing of older film cameras and takes way too long to be sure.

    I do get a confirmation beep when the area of focus happens to be under an AF point with my manual focus, but then I might as well use Autofocus.
     
  4. Socrates

    Socrates TPF Noob!

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    The math is wrong. The 2.676" figure should actually be less than an inch. Assume a 6' correct distance. Then, estimate the distance from her chest to the bridge of her nose to be one foot. Six-squared plus one-squared = 37. Then, the square root of 37 is approximately 6.08 so the focus error is 0.08 foot or slightly less than an inch, much less if my one-foot estimate is too large. Finally, check the DoF for that distance with your lens with whatever aperture you prefer using. Measure with a micrometer and cut with a hatchet.

    Do an experiment. Focus the "wrong" way and then immediately focus the "right" way and see if your lens moves.
     
  5. epatsellis

    epatsellis TPF Noob!

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    Here's an option, swim against the tide and shoot film. Next thing you know, you'll be shooting medium or large format and actually taking the time to compose and get teh exact shot you want. (I'lll probably get hell for this..)

    Of all the cameras in various formats (from 35mm/digital to 20x24), I own 2 autofocus cameras, one is my Nikon F4 and the other my Fuji S2. I don't think it makes one a better or worse photographer, other than you will spend an extra second or two working on composition and framing.


    erie
     
  6. RyanLilly

    RyanLilly No longer a newbie, moving up!

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    I do think that the article over exagerated this problem, Although with focus and recompose there will be a difference in distance it is usually quite small, probably about the same variation created by you or you subject taking a deep breath, between the time you focus and press the shutter.

    Also the article is missing information:

    "When shooting a portrait at a wide aperture, 2-3 inches of focus error can make the difference between just right and just crap. Here's an example; it was shot with a 100mm f/2 lens wide open. Depth of field is about 2 inches, maybe less, look closely at the back of the left hand and the designs on the shirt and you will see how narrow it really is:"

    The DOF will not always be 2 inches, the distance from the camera to the subject will also have an effect, any thing requiring this much control will no doubt call for a tripod, a patient model,and some skill to achieve accurate results anyway, so its kind of a moot point

    Basically yes in very particular situations it could be a problem, but the article makes a mountain out of an anthill. Plus he only offers correctly focused photos with no incorrect photos for comparison.

    To sum up, I often don't have time to fiddle with pesky focus points, often by the time you get it right the subject has moved on. If you in the studio and have lots of time, than use whatever method you like.

    I love to focus and recompose almost as much as I like "Focus, exposure lock, an recompose."
     
  7. Garbz

    Garbz No longer a newbie, moving up!

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    Even with old film cameras I pointed my split prism at the subject, manually focused and recomposed. I'd hate to try this in todays viewfinders with no focusing aid.

    The article also applies exclusively to tripods. There's no saying that what the error is between focusing and recomposing handheld because you're not rotating the camera on an axis 20cm below the lens.

    Mind you for things like macro photography focus and recomposing often isn't an option, especially with a tripod.
     
  8. RyanLilly

    RyanLilly No longer a newbie, moving up!

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    Also the article does make a good point about may people thinking that their new lenses back focus. I think that many people coming from kit lenses are not used to the new "fast" lens that they just bought and do not have good control of DOF.
     
  9. Josh66

    Josh66 Been spending a lot of time on here!

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    I just tried this with my 100mm Macro, it did move a little between the center & leftmost focus points (350D, on tripod).
     
  10. Socrates

    Socrates TPF Noob!

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    Interesting. How close were you focusing?
     
  11. Josh66

    Josh66 Been spending a lot of time on here!

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    Probably about 3 feet, maybe a little more.

    Later today I think I'll do more testing on this, I'll print out some targets and see if I can see a difference at 100%.
     
  12. JerryPH

    JerryPH No longer a newbie, moving up!

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    I do it all the time, and the focus is as sharp as the lens physically permits the pic to be. Technique, I bet is the biggest issue.

    I bet that if I was to watch a video of you doing this, you press the shutter 1/2-way, focus, recompose, and before you stop moving... CLICK!

    If this is happening and the camera is not on a tripod, make SURE you are still 100% before you press the shutter down the rest of the way. Not doing so likely has nothing to do with the focus being off, but because of the motion blur you are causing.

    Thats my guess.
     

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