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Thread: Stop Down or Use Tilt for DOF

  1. #11

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    Re: Stop Down or Use Tilt for DOF

    Quote Originally Posted by cowanw View Post
    Regarding diffraction, I am reminded of Weston's Pepper number 30 shot at f 256.
    https://petapixel.com/2017/08/15/fam...exposure-f240/
    Imagine how much sharper it could have been if it had not been ruined by diffraction!

    Attachment 168851
    Weston was using an older system of aperture designation (US I think). In that system, 256 is equivalent to about f/64. For an 8x10 camera, that's not yet in the range where diffraction is a problem.

    @OP: As Bob points out, placing your plane of sharp focus to optimize depth of field is a good way to keep diffraction at bay. If you use the near-far focus method described in the "How to Focus the View Camera" article on the home page, then a good way to check if your plane of sharp focus is optimally positioned is to find the minimum distance between near and far focus for a given subject. Keep in mind that if you use tilts/swings, the "near" and "far" focus points are not necessarily the closest or most distant, rather those that are in front of and behind the focus plane. For example, if you use front tilt to get a near object and a distant mountaintop in the plane of sharp focus, the "far" focus point will be close to the base of the mountain.

    Best,

    Doremus

  2. #12

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    Re: Stop Down or Use Tilt for DOF

    Possibly, although it was a 4-6 hour exposure (which does not really answer the question)
    "So, Edward made his own stops for his lens, eventually settling on a f/240 aperture — essentially turning the view camera into a pinhole camera. With such a smaller aperture, exposing Pepper No. 30 adequately with natural light required an ultra-long exposure time of about 4-6 hours." according to Kim Weston.
    Bill
    "There are a great many things I am in doubt about at the moment, and I should consider myself favoured if you would kindly enlighten me. Signed, Doubtful, off to Canada." (BJP 1914).

  3. #13
    Mark Sawyer's Avatar
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    Re: Stop Down or Use Tilt for DOF

    Considering Weston was shooting indoors at a small f/stop, 4-6 hours isn't outrageous, especially figuring in bellows extension to twice life size, (that's 4x exposure time right there), plus reciprocity failure. I believe Weston was rating his pinhole aperture by conventional f/stops, not the US System, but I don't know if that was the f/stop for the lens at infinity or with the bellows racked out. Regardless, diffraction is seldom an issue when contact printing, even with ridiculously small apertures. It's when you start enlarging you see the loss of resolution.

    Getting back to the original question of stopping down vs. using tilt, stopping down would be preferable if you're not enlarging enough for diffraction to be an issue. Using front tilts will throw the lens off-axis, although that might be compensated for with rise/fall, while front or rear tilt can cause keystoning, which may or may not be an issue with the image. And btw, the Scheimpflug thing never works in the real world; the universe always has something sticking out from the plane of focus...
    "I love my Verito lens, but I always have to sharpen everything in Photoshop..."

  4. #14
    Lachlan 717
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    Re: Stop Down or Use Tilt for DOF

    To me, diffraction has been made too important a consideration over the last 10-15 years.

    Why?

    Due to bloggers and lens-reviewers on the internet.

    In the early days of digital, there was enough iterations and reiterations of both equipment and technology for even hacks (you know who you are, Ken) to get a following by just reporting the glaringly obvious differences in products.

    However, a combination of slower reiterations and a flood of quasi-experts meant everyone's ramblings were the same.

    So, along comes some "expert" who differentiates his/her review with a formally minor consideration (diffraction at very small apertures), differentiates his/her review with it, leading to a Pavlovian pack of salavating bloggers taking the concept as a primary consideration.

    The same is true, in my opinion, of micro-contrast, bokeh, sun stars, vignetting wide open, zoom breathing, coma, CA and so on.

    Yes, they're considerations, but the relative importance of them has been made way too critical by digital reviewers and their Lemming desciples.
    Lachlan.

    You miss 100% of the shots you never take. -- Wayne Gretzky

  5. #15

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    Re: Stop Down or Use Tilt for DOF

    Hi All,
    I decided to just try out my lenses and see what is sharp and what isn't. I first decided to do something in my studio. I had some Spanish Moss and ferns from fallen branches from Harvey so I set them up by a window. The aperture was f/45 and I was using Acros 100 at EI 50 and Xtol 1:2. The was using my Fujinar 150 mm f/6.3. When I print this out on Epson Hot Press Natural at 5x7 inches, it doesn't look bad, but the top fern leaf does look a bit fuzzy. My DOF was around 4 inches. The subject was about 18 inches from the lens. Not a great shot but I felt it was decent for my first 4x5 still life. The balls of moss were in front of the log so the subject plane was tilted. But I was shooting slightly down, and I did not feel any of the tilts I tried improved focus.

    Next I went outside in open shade and shot a test target with my 150 mm Fujinar, and my 210 mm Schneider APO Symmar f/5.6, both at f/16, and f/45. I messed up the Fujinar test, but this is the result of the 210 mm lens test. I can sort of see more fuzziness in the f/45 shot. I am using a Nikon D5100 to copy the negative and this might also be part of the problem. I realize that this is not a scientific (objective) comparison.

    What do yu'all think?

    Steve

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  6. #16
    Ron (Netherlands)'s Avatar
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    Re: Stop Down or Use Tilt for DOF

    your lenses might be front or back focussing when stopped down....


    ...found this on the different f-stop systems:
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  7. #17
    8x10, 5x7, 4x5, et al Leigh's Avatar
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    Re: Stop Down or Use Tilt for DOF

    Quote Originally Posted by Lachlan 717 View Post
    So, along comes some "expert" who differentiates his/her review with a formally minor consideration (diffraction at very small apertures), differentiates his/her review with it, leading to a Pavlovian pack of salavating bloggers taking the concept as a primary consideration.
    The same is true, in my opinion, of micro-contrast, bokeh, sun stars, vignetting wide open, zoom breathing, coma, CA and so on.
    Yes, they're considerations, but the relative importance of them has been made way too critical by digital reviewers and their Lemming desciples.
    Hmmm...

    It seems I agree 100% with Lachlan for once. Will wonders never cease?

    - Leigh
    If you believe you can, or you believe you can't... you're right.

  8. #18
    8x10, 5x7, 4x5, et al Leigh's Avatar
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    Re: Stop Down or Use Tilt for DOF

    Quote Originally Posted by Ron (Netherlands) View Post
    ...found this on the different f-stop systems:
    The "Uniform System" progresses by powers of 2. Each step = the previous step times 2.

    The "International" scale progresses by the square root of 2. Each step = the previous times 1.414214.
    This is why our aperture scale looks so weird.

    What that does is make the AREA of each aperture = half or twice the AREA of the adjacent aperture.

    -Leigh
    If you believe you can, or you believe you can't... you're right.

  9. #19

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    Re: Stop Down or Use Tilt for DOF

    Quote Originally Posted by Lachlan 717 View Post
    To me, diffraction has been made too important a consideration over the last 10-15 years.

    Why?

    Due to bloggers and lens-reviewers on the internet.

    In the early days of digital, there was enough iterations and reiterations of both equipment and technology for even hacks (you know who you are, Ken) to get a following by just reporting the glaringly obvious differences in products.

    However, a combination of slower reiterations and a flood of quasi-experts meant everyone's ramblings were the same.

    So, along comes some "expert" who differentiates his/her review with a formally minor consideration (diffraction at very small apertures), differentiates his/her review with it, leading to a Pavlovian pack of salavating bloggers taking the concept as a primary consideration.

    The same is true, in my opinion, of micro-contrast, bokeh, sun stars, vignetting wide open, zoom breathing, coma, CA and so on.

    Yes, they're considerations, but the relative importance of them has been made way too critical by digital reviewers and their Lemming desciples.
    Face it, if they could take photos, they would not be writing! L

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