wrong what? (or live with the limitations)

Discussion in 'Large Format Cameras and Accessories' started by Ruvy, Oct 30, 2005.

  1. Ruvy

    Ruvy Member

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    Hi
    Still learning so no surprise finding lots of problems to overcome. One of which is shooting from a close distance subjects that behave less friendly than expected ;-). All of the following images were shot from a distance of one meter or less with Plaubel Peco profia view camera and caltar II N 150mm. All required heavy tilting (lots of front and often additional back tilting - all for sharpness only) and f32 but even so, All I could have done was to get this part sharp or the other but not all of it.

    Question are: 1. Am I using the right lens for the job (maybe a longer and further placed lens would have solved the problem)?
    2. Wouldn't I have been better off without tilting?

    I have seen some posters place a little icon of an image and when you point to it the full image opens up (unlike what I have done bellow) can someone explain how its done?

    Anyway, here are the problematic images:
    base or front?
    [​IMG]

    back or front?
    [​IMG]
     
  2. gbroadbridge

    gbroadbridge Member

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    There are no images. Are you sure you haven't posted a shortcut instead of an actual file?
     
  3. Ole

    Ole Moderator Staff Member Moderator

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    I can see the images...

    And the answers are: 1: Yes (no), and 2: Maybe...
     
  4. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator

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    You're in the macro range, so DOF is going to be pretty short. I'm guessing magnification here is about 1:2 in the second image (size of the image on film:actual size of the object).

    The choices are either to try to use that short DOF in an interesting way, or shoot a smaller format, so the magnification ratio will be smaller given the same field of view and DOF will be greater (though it's not going to help that much).

    The only reasons to use a longer lens would be if you needed more working room for lighting, or if you felt it would give you a more natural perspective. 210mm is a common focal length for studio tabletop work on 4x5", for instance.
     
  5. Paul Sorensen

    Paul Sorensen Member

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    As for whether you would have been better off without tilts; on the first image if your lens had been paralell to the film plane, the base of the stand would have been more in focus. Of course, the top would not have been in focus as well. I suspect your best results, assuming that having everything in focus your goal, would have been either no tilt, or tilting so that the plane of focus is paralell to the ground. That combined with stopping down another stop or two might have gotten you closer to having everything in focus and, at the very least, the focus would have looked more natural.
     
  6. gbroadbridge

    gbroadbridge Member

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    I see the images now too. My apologies for the short comment before.

    Graham
     
  7. Bob F.

    Bob F. Member

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    Impossible to say if you could have got better DoF without being there and trying it, but I can attempt an answer to a couple of points... Tilting the back has much the same effect as tilting the front (tilting in the opposite direction) so you may want to avoid confusion and only tilt one of them.

    Changing lens will make no detectable difference to the DoF that you get (this has been debated endlessly in other threads...).

    The icon you mention is a function of the web browser in which you view the image. If an image is larger than the current browser window, there is the option for the browser to reduce the size of the image so that it fits within the window. The icon is added by the browser to allow you to see the image at its full size. Depending on the browser, the option is called something like: "Enable automatic Image Resizing" or "Resize large images to fit the browser window".

    Cheers, Bob.
     
  8. User Removed

    User Removed Guest

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    Use a wider angle lens, and get a shutter that stops down more then 32.
     
  9. Ole

    Ole Moderator Staff Member Moderator

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    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.
     
  10. Alexz

    Alexz Member

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    Bob, just a side note:
    I'm now in my learning curve in theoretical LF, and according to Simmon's well known book (or at least as I understood this particular issue), tilting back has lesser effect on DOF comparative to tilting front. According to him, to obtain desirable focus plane usually front tilt is used whilst back tilt is more useful for perspective correction, for instance. Of course, back tilt also alters focus plane (all according to Scheimpflug law), but in far lesser effeciency then front tilt.
     
  11. Bob F.

    Bob F. Member

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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...
     
  12. Donald Miller

    Donald Miller Member

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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
     
  13. Paul Sorensen

    Paul Sorensen Member

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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 Files:

  14. Alexz

    Alexz Member

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

    Ruvy Member

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    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
     
  16. Ruvy

    Ruvy Member

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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


     
  17. Ruvy

    Ruvy Member

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    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
     
  18. Donald Miller

    Donald Miller Member

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    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.)
     
  19. Ruvy

    Ruvy Member

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    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)