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Thread: Technique for focusing "into your scene"

  1. #101

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    Re: Technique for focusing "into your scene"

    To maximize DOF in any LF image, I was taught as follows:

    1. Visualize the end product (image) you are seeking
    2. Choose a lens which provides an appropriate Angle of View
    3. For typical landscape scenes, set camera base parallel to the ground (assuming it is flat or relatively so).
    4. Set back perpendicular to base (90 degrees) so that WYSIWYG from a linear distortion perspective. So film is essentially parallel to trees and buildings (again assuming no slope in the scene).
    5. Determine the most efficient plane of focus. Without movements, that is the same as the film plane. With front tilt that diagonal changes to maximize DOF in the entire scene.
    6. Whatever the Plane Of Focus, you will have an area in front of and behind the point of focus 1/3, 2/3)
    7. The DOF for subjects that are closer to the camera is much less than those in the distance, so critical focus should be on subjects closest to the camera first.
    8. Do not use rear tilt unless you cannot maximize DOF by using front tilt. Rear tilt creates linear distortion in the image and though not necessarily discernable in the final image, it adds a new dimension of adjustment which may not be ideal.
    9. If the subject closest to the camera rises above the lower half of the GG, front tilt becomes less useful.
    10. To set tilt for the farthest subject (i.e. trees, buildings etc), intersect the most salient point just below its highest point. Adjust tilt (and swing) by stopping down the aperture while viewing the DOF under the dark cloth.
    11. Use Front Rise to adjust for converging lines as necessary
    12. Use Front Swing very sparingly and only if you are not compromising one part of the image to maximize DOF in another part.
    13. Use an appropriate aperture (don't hesitate to us F64 if necessary).

    Click image for larger version. 

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    Here is an image in which the front tilt was used to maximize DOF. Focused first on the foreground flowers, tilted to intersect just below the tops of the distant trees, stopped down to f16 gradually to see what was not in focus, adjusted tilt accordingly, stopped down to F45. 90MM Nikkor, Velvia 50.

    There is an image by Jack Dykinga (no longer on his website but in one of his books), where he has created a hard core closeup (very close to the camera) of wild columbine flowers which filled the lower part of the image, and he tilted to include the distant mountain in focus. Even stopping down to F45 or beyond, and because critical focus and therefore very limited DOF was available for the high degree of magnification of the flowers, DOF was non-existent in flower stalks deep into the image, and he lost DOF on the lower valley below the mountain. My guess is that he used a 65mm or 75mm lens to create the image.

    Another way to manage DOF in the image if you can't get it with movements, is to reduce the degree of foreground magnification by moving back, using wider angle lens etc, and cropping. Another option though not practical for LF is to use focusing stacking techniques.

  2. #102
    Vaughn's Avatar
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    Re: Technique for focusing "into your scene"

    Alan....You have near/far (fence and base of barn) right next to each other. They cannot exist on the same focus plane using just tilt.
    "Landscapes exist in the material world yet soar in the realms of the spirit..." Tsung Ping, 5th Century China

  3. #103

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    Re: Technique for focusing "into your scene"

    Plane of focus diagonal from just below top of fence to just below top of Conifer in the distance (not the clouds). A small amount of left swing might help as well. With a 150mm my guess is f32 should be sufficient.

  4. #104
    Alan Klein's Avatar
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    Re: Technique for focusing "into your scene"

    Quote Originally Posted by Benjamin View Post
    If you defined your plane of sharp focus at a high angle - from beneath the camera straight to the clouds - it's possible that you've excluded stuff that lies under the lower depth of field plane.

    Do you remember which aperture you used?
    F/22. 150mm lens.

  5. #105
    Alan Klein's Avatar
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    Re: Technique for focusing "into your scene"

    Quote Originally Posted by Vaughn View Post
    Alan....You have near/far (fence and base of barn) right next to each other. They cannot exist on the same focus plane using just tilt.
    So the circled areas are out of focus because I needed swing too??

  6. #106

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    Re: Technique for focusing "into your scene"

    Alan...it looks like you were in the ballpark (given your focus-goals for this image) with respect to image plane adjustment, except that you might have adjusted your actual focus to get a bit closer to those out of focus areas.

    Additionally, you could have gone to f/32 to squeeze out a bit more DOF. This could help in another way also - that while a 150 may begin to show just a bit of diffraction at this aperture, the actual visible effects of this, on a print (unless it is to be very large) will be minimal...but may just be enough to "smooth over" any visible focus transitions between the actual, chemical focus plane and areas slightly away from this plane. I'm not talking about actual DOF here...but "perceived" DOF based on just a wee bit of diffraction occurring at the actual focus plane.

    Perhaps we could add another definition here, as DOF can already be a bit subjective. I guess another way to express this would be to imagine that diffraction itself somehow did not exist...and that you could then be more or less free to stop the lens down to wherever (so long as other conditions did not interfere). Then, imagine what the visible DOF might look like...larger, yes, but with still markedly visible transitional cues. But then add diffraction back into the equation - and the exact focal plane begins to look a bit more like the very beginning of the transitional zone in our "impossible" (no diffraction) example (maybe not on a micro level, but a macro one), and thus the entire transitional zone appears to be extended further. (Not sure if I'm even making sense to myself at this point, but give this some thought).

    Yet another ally here could be just to add a bit of (or a bit more of) contrast-adding filtration and/or processing ...which would further act to enhance the "illusion" of (in focus) sharpness (possibly at the expense of some deep shadow detail). Make sense?

  7. #107

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    Re: Technique for focusing "into your scene"

    Quote Originally Posted by Alan Klein View Post
    F/22. 150mm lens.
    Alan, if this is repetitive apologies, but have you seen this type of diagram (attached)? It's a simplified picture to illustrate what goes on in the case of lens tilt (for example). Might help in visualizing what happens and aid in the discussion.Click image for larger version. 

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  8. #108
    Vaughn's Avatar
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    Re: Technique for focusing "into your scene"

    Quote Originally Posted by Alan Klein View Post
    So the circled areas are out of focus because I needed swing too??
    It might help, but you still might have trouble with that lower right area circled -- swing will make that area worse...you need to go to f45 or f64. The diagram above shows what happened. You just need to widen the DoF to include the ground by closing down the lens.

    F22 sucks if it gives you out of focus areas -- not matter how 'sharp' they are. Sharp renditions of out-of focus-areas are still out of focus!

    But don't forget that where you focus also is very important. Try this 'trick'. Once you have focused your camera and made your movements (try this on a simple scene), with the lens wide open, look at the GG as you slowly reduce the aperture. The near and the far will start to come into focus as you reduce the aperture. If they come into focus at the same time, then you have placed the focus well. If far comes into focus first, you might need to pull the focus in a little until they do (and the reverse if the near comes into focus first).
    "Landscapes exist in the material world yet soar in the realms of the spirit..." Tsung Ping, 5th Century China

  9. #109
    Drew Wiley
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    Re: Technique for focusing "into your scene"

    Unless you are using a precision vacuum or adhesive filmholder, f/22 might not compensate for even potential film sag, at least with 5x7 and larger formats. It's less of a factor with smaller 4x5 film. But the shorter the lens, the more significant lack of precise film plane we be, in terms of ACTUAL focus. None of the fancy-schmancy math on this thread takes into account that fact.

  10. #110
    Alan Klein's Avatar
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    Re: Technique for focusing "into your scene"

    Quote Originally Posted by John Layton View Post
    Alan...it looks like you were in the ballpark (given your focus-goals for this image) with respect to image plane adjustment, except that you might have adjusted your actual focus to get a bit closer to those out of focus areas.

    Additionally, you could have gone to f/32 to squeeze out a bit more DOF. This could help in another way also - that while a 150 may begin to show just a bit of diffraction at this aperture, the actual visible effects of this, on a print (unless it is to be very large) will be minimal...but may just be enough to "smooth over" any visible focus transitions between the actual, chemical focus plane and areas slightly away from this plane. I'm not talking about actual DOF here...but "perceived" DOF based on just a wee bit of diffraction occurring at the actual focus plane.

    Perhaps we could add another definition here, as DOF can already be a bit subjective. I guess another way to express this would be to imagine that diffraction itself somehow did not exist...and that you could then be more or less free to stop the lens down to wherever (so long as other conditions did not interfere). Then, imagine what the visible DOF might look like...larger, yes, but with still markedly visible transitional cues. But then add diffraction back into the equation - and the exact focal plane begins to look a bit more like the very beginning of the transitional zone in our "impossible" (no diffraction) example (maybe not on a micro level, but a macro one), and thus the entire transitional zone appears to be extended further. (Not sure if I'm even making sense to myself at this point, but give this some thought).

    Yet another ally here could be just to add a bit of (or a bit more of) contrast-adding filtration and/or processing ...which would further act to enhance the "illusion" of (in focus) sharpness (possibly at the expense of some deep shadow detail). Make sense?
    If I was to use "digital" printing from a scan, then I would be adjusting contrast and sharpness when I edit in Lightroom. That shows in the larger link for that photo I showed above, copied here: https://www.flickr.com/photos/alankl...7714124881023/ So, I suppose the original f/22 and "out-of-focus" areas will be better?

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