Film choice is very personal. Each film-developer combination provides a result with a "personality", which can be unique to the person who does the processing. Identical film-developer combinations, in the hands of different people, can produce significantly different results.

You MUST devise your own tests with YOUR equipment and YOUR procedures! ... AND... EVALUATE YOUR RESULTS AGAINST YOUR STANDARDS!

Extreme enlargements are frequently used to compare film resolution and grain. The result of this series of tests leads me to question that approach in favor of seeking an answer to the question -
"For a given situation, equipment mix, and print quality standard, to what degree can the negative be enlarged before the film itself becomes the critical factor?"

Enlargeability is a function of both film and scene characteristics.

While I have not been able to produce, at 72ppi, images which accurately illustrate the differences in granularity, resolution, and personality between the films tested, I did discover some of the factors which influenced the results.

• Accuracy of focus.
• Accuracy of film registration in the camera - film thickness may be a factor.
• Stability of the camera.
• Nature of the film emulsion.
• Precision of exposure -
  • Overexposure can cause sharp dense edges of the negative to "bleed" into less dense areas.
  • Over and under exposure affect the contrast of the negative, which affects apparent sharpness.
• Grain structure - sharp (and to an extent larger) grain may add "crispness" which is interpreted as image sharpness.
• Scene luminance range - high contrast scenes and objects with great density differentials appear sharper.
• Developer selection, and development procedure.
  • "Edge effects" - reduced agitation can cause developer exhaustion along high contrast edges which can enhance the appearance of sharpness.

Apparent GRANULARITY is influenced by the following:

• Nature of the film emulsion - slower film tends to be finer grained.
• Developer - composition and concentration cause significant grain and accutance differences, can dissolve or soften edges of the grain clumps
• Development scheme - agitation scheme and "wet time" can influence grain and accutance.
• Density of the negative - grain is most evident in "middle" gray areas and least noticeable in the low values. The nature of the scene has great influence on the apparent granularity.

IMAGE CHARACTER is influenced by the following:

• Contrast is inversely related to emulsion speed.
• Luminance range generally increases with emulsion speed.
• Spectral response varies, even with B&W film.
• Image personality is greatly influenced by the shape of the film characteristic curve.
• The effects of reciprocity. Long exposures can significantly increase contrast, providing a powerful tool for influencing image character.
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