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  1. #11
    Bob F.'s Avatar
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    Have not heard of front/back tilt giving a different DoF - certainly perspective is different as you can clearly see on the gg, but I am not aware that DoF is different once sufficient tilt is applied to get the focus plane at the same optimum angle for your subject. As the lens focal length and magnification is the same, I would not expect a change in DoF. Perhaps others with a fuller mathematical/optical knowledge can comment if this general rule changes in these close-up situations...

    Cheers, Bob.

    P.S. Ignore my Web browser diversion - I see Ole understood your question while I misunderstood it...

  2. #12

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    I will address your questions using your second image as the example in what follows.

    Determining the principal plane of focus is the first thing that one should do when photographing an image of this type. If the vertical orientation of the small statue is chosen the principal plane of focus then the depth of field required is from the front of the bath to the rear of the bath. (fairly large distance in this example)

    If conversely the horizontal level of the water in the bath is chosen as the principal plane of focus then the depth of field required is the height of the small statue to the level of the water. (much less, in this example).

    If I would have taken this image I would have placed the horizontal axis of the camera about 20- 30 degrees above the top and in front of the small statue. I would first have tilted the entire camera downward using the tripod head. Then I would have worked with my front tilt on the camera to bring the front of the water and the rear of the water in the bath into focus. I would next have focused the camera by using the front rise/fall and rear focus to focus on the knees of the small statue and lastly stopped down the lens to bring everything into acceptable focus.

    Good luck.

    Donald Miller

  3. #13
    Paul Sorensen's Avatar
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    Hey, the icon issue. When you post, there is a button at the bottom that says "manage atachments." Click it and upload your photos. What you get is a little area at the bottom of your post that has thumnails and says "attached files."

    I have done it so you can see what I am talking about. The attachment is a screen shot of this form.
    Attached Thumbnails Attached Thumbnails post.jpg  

  4. #14

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    Sorry Bob, I didn't mean DOF, I was rather talking about focus plane. Sort of typo...

  5. #15

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    Quote Originally Posted by Donald Miller
    I will address your questions using your second image as the example in what follows.

    If I would have taken this image I would have placed the horizontal axis of the camera about 20- 30 degrees above the top and in front of the small statue. I would first have tilted the entire camera downward using the tripod head. Then I would have worked with my front tilt on the camera to bring the front of the water and the rear of the water in the bath into focus. I would next have focused the camera by using the front rise/fall and rear focus to focus on the knees of the small statue and lastly stopped down the lens to bring everything into acceptable focus.

    Good luck.

    Donald Miller
    Thank you Donald, you have added one direction and one step I didn't use in that image however in the first image choosing a direction didn't make much difference it was either the front of that bath that will OOF or its base depending on the direction.. There is however one thing you have mention that I am not sure I fully understand. The way I work is first set rise and fall if needed to set the proper composition, than use the move the front standard until the rear of the scene is sharp and than tilt the front standard till the front of the scene is sharp. most of the time I have to go back and forth with the linear movement of the standard and its tilt until I get the entire range sharp. Often I hit a limit (dictated by the presence of the bellow) of how much the front can tilt at which point I start with rear standard tilting. I am not sure I am doing it right but this is another story. What was interesting in your comment is that you use the front rise to focus - can you explain what and how?

    Thanks

    Ruvy

  6. #16

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    Paul and Bob

    Thanks for explaining about making the thumbnail. I like how the thumbnail looks and feels better than the way I have presented it on this thread - will try it next time

    Ruvy


    Quote Originally Posted by Paul Sorensen
    Hey, the icon issue. When you post, there is a button at the bottom that says "manage atachments." Click it and upload your photos. What you get is a little area at the bottom of your post that has thumnails and says "attached files."

    I have done it so you can see what I am talking about. The attachment is a screen shot of this form.

  7. #17

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    Quote Originally Posted by Ole
    Wider angle lenses do nothing for DoF at there reproduction ratios. Wider (shorter) or longer lens lets you work closer or farther away, nothing else.

    The reason your pictures show up in full size is that you used the "[ IMG]" tag. If you had put the pictures in as an attachment instead you would have had the thumbnails.
    Thank you David and Ole,
    I always look for a magic bullets to make my life easier. I have a problem with my 150mm and intend to replace it with another lens that will be my only lens until I master the camera. Your definite reply on this thread helped me decide to replace the 150 with same.

    thanks
    Ruvy

  8. #18

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    Quote Originally Posted by Ruvy
    Thank you Donald, you have added one direction and one step I didn't use in that image however in the first image choosing a direction didn't make much difference it was either the front of that bath that will OOF or its base depending on the direction.. There is however one thing you have mention that I am not sure I fully understand. The way I work is first set rise and fall if needed to set the proper composition, than use the move the front standard until the rear of the scene is sharp and than tilt the front standard till the front of the scene is sharp. most of the time I have to go back and forth with the linear movement of the standard and its tilt until I get the entire range sharp. Often I hit a limit (dictated by the presence of the bellow) of how much the front can tilt at which point I start with rear standard tilting. I am not sure I am doing it right but this is another story. What was interesting in your comment is that you use the front rise to focus - can you explain what and how?

    Thanks

    Ruvy
    I am not sure that you caught the distinction of the primary plane of focus.

    There are two that are possible in your image. The first is vertical (the orientation of the small statue. The second is horizontal (the orientation of the surface of the water in the bath).

    Since the linear measurement of the surface of the water is greater then the linear measurement of the statue and vertical elements in the image, it makes sense to choose the greater linear measurement for the primary plane of focus. This is accomplished by using camera tilt via the tripod head and the front tilt of the camera. In other words...the surface of water at the rear of the bath and the front of the bath are the first two points of sharp focus accomplished by overall camera tilt and front standard tilt.

    Once this is accomplished the depth of field in the image becomes the other orientation (the vertical elements including that of the statue). This point of focus into this depth of field would be approximately 1/3 of the height of the vertical elements. This focus point would be accomplished by using the rising/falling front.

    Stopping the lens down is the last step in the process.

    (It is important to grasp that the depth of field in my description is not front to rear but rather top to bottom.)

  9. #19

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    Quote Originally Posted by Donald Miller
    I am not sure that you caught the distinction of the primary plane of focus.

    There are two that are possible in your image. The first is vertical (the orientation of the small statue. The second is horizontal (the orientation of the surface of the water in the bath).

    Once this is accomplished the depth of field in the image becomes the other orientation (the vertical elements including that of the statue). This point of focus into this depth of field would be approximately 1/3 of the height of the vertical elements. This focus point would be accomplished by using the rising/falling front.

    (It is important to grasp that the depth of field in my description is not front to rear but rather top to bottom.)
    What you describe sounds very basic, yet, when discussing the vertical depth of field I don't understand why/what governs the 1/3 you have mentioned (though intuitively it sounds right)

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