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  1. #11

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    My results with T-max 100 film in Xtol 1+0 (solvent) and FX-1 (Acutance) don't show much difference in resolution.Photomicrographs of negatives of test chart, numbers on chart are resolutions in line-pairs per millimeter.
    Lens was Canon ef 50mm f1.8 at f5.6.
    Attached Thumbnails Attached Thumbnails xtol tmax.jpg   FX-1 tmax.jpg  

  2. #12
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    Quote Originally Posted by Alan Johnson View Post
    My results with T-max 100 film in Xtol 1+0 (solvent) and FX-1 (Acutance) don't show much difference in resolution.Photomicrographs of negatives of test chart, numbers on chart are resolutions in line-pairs per millimeter.
    Lens was Canon ef 50mm f1.8 at f5.6.
    Considering the size and contrast differences, it is a bit hard to judge.

    PE

  3. #13

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    Quote Originally Posted by CBG View Post
    If something is the best advice, then why would the OP want less.

    In the case of suggesting "The Film Developing Cookbook", the OP got a very good piece of advice. The book contains far more information than would be manageable to communicate within the constraints of a forum.
    I do own a copy.

    While it explains the difference (which is rather obvious) between accutance and resolution; it does not present any useful information on how developer type affects resolution.

    While Bill Troop is a photochemist, the primary author (Steve Anchell) is not.
    Digital Photography is just "why-tech" not "high tech"..

  4. #14

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    Quote Originally Posted by RalphLambrecht View Post
    My response may not be precisely what you're looking for, but hopefully it helps to clarify a couple of thinks.

    To me, sharpness (or image clarity) has three components, resolution, acutance and contrast. With 'acutance' I mean 'edge contrast' and with 'contrast' I mean overall image contrast. Film development has a large influence on acutance and contrast but only a minor influence on resolution, which is mostly coming from a good lens combined with a fine-grain emulsion.

    Certain film developers work better for acutance than others, but one very important aspect of acutance is the development technique. Optimum acutance requires standing development. Rotation and even 30s-interval inversion techniques destroy most of what a good acutance developer can do.

    By the way, subjective image evaluations clearly show that there is an importance ranking for the three components of sharpness.

    1. contrast (high)
    2. acutance (high)
    3. resolution (low)

    A high-contrast image looks sharper than a soft one, and high acutance is often mistaken for resolution (that why unsharp masking works). Resolution is not necessarily seen as sharpness. Indeed, a high-contrast, low-resolution image is often perceived as being sharper than a low-contrast, high-resolution image. If you have a choice, go for acutance and contrast and forget resolution (it works for digital, it will work for you).

    To prove the point about digital, I have not measured a on-chip resolution of more than 60 lp/mm on any digital camera, but good 35mm lenses combined with fine-grain film can easily achieve over 100 lp/mm. Still, you would be hard pressed to see the difference between the two on an 8x10 print. Why? At that magnification, the resolution of both is beyond human detection, but increasing the acutance of the digital image is as easy as a mouse click. The story quickly changes in favor of film at larger magnifications.
    Very interesting point about the relative importance of the three components of sharpness.

    I have read on the web that with the emergence of thin emulsion films in the 1950s, lens designers shifted their emphasis to optimizing contrast across the frames, rather than outright maximization of resolution.
    Digital Photography is just "why-tech" not "high tech"..

  5. #15

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    Quote Originally Posted by aldevo View Post
    I do own a copy.

    While it explains the difference (which is rather obvious) between accutance and resolution; it does not present any useful information on how developer type affects resolution.

    While Bill Troop is a photochemist, the primary author (Steve Anchell) is not.
    Developers that limit the migration of silver halide during development may result in a more precise reduction. A developer that tans and hardens the gelatin during development may reduce the effects of irradiation and infectious development (spreading of silver development beyond the exact image boundaries). Pyro staining developers also tan the gelatin, but there are other reducers that also tan and harden gelatin. Ron may want to mention a few.

    To obtain the maximum resolution requires that the film be given correct exposure and development. To much of either will result in spreading of the silver development outside of the image area.

    Sandy king
    Last edited by sanking; 06-15-2009 at 02:38 PM. Click to view previous post history.

  6. #16
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    Quote Originally Posted by RalphLambrecht View Post
    To prove the point about digital, I have not measured a on-chip resolution of more than 60 lp/mm on any digital camera, but good 35mm lenses combined with fine-grain film can easily achieve over 100 lp/mm. Still, you would be hard pressed to see the difference between the two on an 8x10 print. Why? At that magnification, the resolution of both is beyond human detection, but increasing the acutance of the digital image is as easy as a mouse click. The story quickly changes in favor of film at larger magnifications.
    Not entirely. Digital has a linear grid for the 'dots'. Film grain moves with the light and processing, thus is uneven in it's distribution. This gives the blacks in film a much richer look and the greys in digital a much more linear graduation.

    Depending on the shot, film and digital will show different aspects of the lens. The same, yet different.

  7. #17

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    Quote Originally Posted by Photo Engineer View Post
    I have made a rather extensive series of posts on macro and micro edge effects and the contrast effects that also take place. You may want to look them up to further extend your understanding of this.

    PE
    Exactly the sort of response I was hoping to get.

    I will look them up. Thanks, PE!
    Digital Photography is just "why-tech" not "high tech"..

  8. #18

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    Aldevo,

    I think you have it exactly right, except that D-76 is considered a moderately fine grain developer rather than an accutance developer. For the best resolution, you probably don't want the highest accutance developer. Best resolution is usually acheived with a lower contrast light-to-dark transition, whereas highest accutance is acheived with a higher contrast light-to-dark transition.

    Charlie Strack

  9. #19
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    Developers can be maximized for any two of the following: Grain, sharpness and speed. Normally, you cannot maximize all 3 but you can strike a happy medium.

    Alan's experiment above is one of the best comparisons I have seen on APUG in spite of my comments. More like it should be done to "prove" a theory or observation.

    PE

  10. #20

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    Quote Originally Posted by Photo Engineer View Post
    Developers can be maximized for any two of the following: Grain, sharpness and speed. Normally, you cannot maximize all 3 but you can strike a happy medium.

    Alan's experiment above is one of the best comparisons I have seen on APUG in spite of my comments. More like it should be done to "prove" a theory or observation.

    PE
    But is not the lens the limit of resolution in Alan's test, not the developer? I have done tests by contact printing high resolution chrome on glass targets and with Tmax-100 I was able to get somewhere around 160-180 lines per mm with pyro staining developers.

    Sandy

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