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Thread: DOF vs Tilt

  1. #11

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    Re: DOF vs Tilt

    Quote Originally Posted by cmcdarris View Post
    ... My question is this: Why not just use DOF of the large format lens and just leave the Large Format camera “zeroed out”, ie - no tilt? Setting it on f64 will surely give sharp detail from foreground to background in the scene. Thanks for the input.

    Charlie
    Charlie,

    LF photographers are always trying to optimize aperture and shutter speed. The reasons for this are directly related to the size of the film (i.e., more important the larger the format). There are many situations where one simply can't stop down enough to get everything into sharp focus without either getting into diffraction degradation or ending up with a shutter speed that is impossible to use with a moving subject.

    Firstly, as has been pointed out, the sharpest aperture for most LF lenses is around f/22. Ideally, one would want to shoot at that aperture or as close to it as possible. So, when the DoF at f/22 won't do the job, one can often use tilt and swing to reposition the plane of sharp focus in order to be able to shoot at f/22 or thereabouts. For many shots, especially those with tall objects close to the camera and important distant objects, there isn't much tilt you can apply. However, you'd be surprised how much even a little helps with aperture choice. I shoot architecture a lot, often a building with a bit of foreground. I can often save a stop or two by simply tilting the front standard so that the plane of sharp focus includes a close foreground object and the top of the building This then becomes my "near" and whatever is farthest from that becomes my "far." I can often reduce focus spread significantly (see the articles on the LF home page about focusing the view camera and choosing the f-stop). FWIW, however, my most used f-stop is f/32. This gives me prints up to 20x24 without enough diffraction degradation to bother me.

    Secondly, we often have to use a faster shutter speed than would be optimal in order to stop movement in the scene, especially with landscapes. Wind, moving water, etc. require relatively fast speeds, which in turn, need wider apertures. Again, we can often use tilt/swing to reposition the plane of sharp focus to allow us to get the objects in the scene in sharp-enough focus and gain a stop or two wider aperture which can then allow the shutter speed to be faster.

    A third consideration is image manipulation. Often we want to emphasize a foreground object, emphasize convergence or change the relative size of objects in the scene. This is done by tilting the back. Many use wide apertures and tilt/swing to manage the in-focus and out-of-focus areas in their images. These, however, are less-directly related to DoF and aperture size.

    Hope this helps,

    Doremus

  2. #12

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    Re: DOF vs Tilt

    A Doremus pointed, a tilted plane of focus is not only used to place subjects in focus, but also to place objects in the scene out of focus, this allows for awesome creative effects.

    Like in this image https://www.flickr.com/photos/colton...125592977@N05/

    or this one, there is OOF under flowers, and in the lake:

    https://www.flickr.com/photos/timpar...125592977@N05/

  3. #13

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    Re: DOF vs Tilt

    Doremus

    Although it isn't pertinent to this thread, I just came across an article from you in an old edition of 'View Camera' which featured this terrific image:-

    http://www.doremusscudder.com/Death-...66&s=570&id=63

    regards

    Andrew

  4. #14

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    Re: DOF vs Tilt

    Quote Originally Posted by Andrew Plume View Post
    Doremus

    Although it isn't pertinent to this thread, I just came across an article from you in an old edition of 'View Camera' which featured this terrific image:-

    http://www.doremusscudder.com/Death-...66&s=570&id=63

    regards

    Andrew
    Andrew,

    Thanks for the compliment and directing people to my website I think the image in the article was the first one in the gallery, "Zabriskie Point, Dawn" in case any are curious as to exactly which image you are referring to.

    BTW, my article on basic field camera movements used to be on the free articles page of the View Camera website. I'm not sure it's still there. If anyone is interested, I'll happily send them my pdf-proof of the article (complete with typos).

    Best,

    Doremus

  5. #15

    Re: DOF vs Tilt

    Modern LF lenses tend to be optimized for f22, but this is not always the case for vintage lenses. The f22 ideology appears to come from the LF-Group f64 of everything in the image must be sharp. Images made on LF sheet film does not always need to have it's optics stopped down to f22 or smaller to achieve overall image sharpness. There are many factors that affect overall image sharpness and the aperture required to achieve this.

    Example, Group image made using a 8 1/2" Kodak Commercial Ektar in barrel with a Sinar shutter on a Sinar 5x7 camera on a honking heavy Gitzo tripod with Sinar Pan-Tilt head. Taking aperture was full open, f6.3. This had to be due to the time of day, potential movement of the individuals in the image and slow film speed. The resulting image is plenty sharp for prints up to 4-5x.

    https://secure.meetupstatic.com/phot...416541752.jpeg


    Point being, there are a host of factors that affect overall image sharpness and the orthodoxy of stopping down to f22 or smaller is required being simply not always true.
    It does require camera stability (weight), precision (often metal with precision made mechanicals), proper use of camera movements as needed, heavy and stable tripod then optics that are not optimized for the f22 and smaller aperture ideology. As perviously mentioned, f22 is not a commonly used aperture on 5x7 for the images I'm making. Typical would be f16 with carefully applied camera movements for image made near infinity focus or far distances, using larger apertures is often much less significant problem. At shorter image distances (lesser increased the problem greatly), achieving sharp definition overall can become challenging to not possible.


    The microscope image makers using film have a similar problem of exposure time due to low level of light reaching the imager. One of their solutions is similar to making night images with film, increase the film exposure time to allow the image to form on the film over an extended duration of time. This reduces the unstable images that are out of sync with the image being gathered over the time of exposure.



    Bernice

  6. #16

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    Re: DOF vs Tilt

    Quote Originally Posted by Bob Salomon View Post
    You can open up a lens to, say, 5.6 but you would stop down a lens to f32. But on 45 that would also be in diffraction. Most lenses for 45 perform optimally at f22.
    Yes, I know. I was just commenting on DoF calculations.

  7. #17

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    Re: DOF vs Tilt

    Although it doesn't seem like it when you start out, tilts and shifts actually make your life a lot easier and are pretty intuitive to use in real-life situations. I came up from shooting medium format and wouldn't be without movements and my LF camera now . It really does make certain pictures much easier to capture and shifts are brilliant for fine tuning compositions on a tripod.

  8. #18
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    Re: DOF vs Tilt

    I have heard it called depth of focus. You can change the plane of sharp focus now that you are a 4x5 guy.

    To the OP: knob focus on the far.....tilt for the near. Do this wide open and then re-focus a few times as needed. You will be amazed what you can get kinda sharp at 5.6 with a 210 mm lens. The subject, the focal length of the lens and the distance to the subject have everything to do with being able to get the focus right.

    Sometimes you just cant get it all.

    When you get all you can wide open.....then you stop down to F-16, 22, 32 to get the rest. It's not fast but, it can be fun.

    Don

  9. #19

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    Re: DOF vs Tilt

    Thanks Doremus, appreciated indeed

    regards

    Andrew

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