Push Pull Processing by liamei12345

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									KODAK: Processing: Push / Pull Processing                                              http://motion.kodak.com/US/en/motion/Support/T ec...



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          KODAK IMAGECARE Program                  Push / Pull Processing
          Laboratories Directory
                                                   Eastman Kodak recommends a controlled ECN-2 process (as specif ied by the H-24 manual)
          Transfer Facilities Directory
                                                   f or the optimum perf ormance of all of its color negativ e f ilms. Howev er, it is recognized that
          People & Planet                          creativ e control and/or phy sical limitations may dictate exposing f ilm under less than ideal
                                                   conditions (i.e. normal exposure). This may necessitate the use of push / pull chemical
           FAQ
                                                   processing conditions to compensate f or the non-standard exposure / speed conditions that
                                                   are used f or the f ilm.
          Technical Information
           Glossary of Motion Picture              Normal ECN processing = 3 minutes (180 sec.).
           Terms                                   This is the recommended processing time used f or normal ECN exposure - (exposure of f ilm
                                                   at the rated speed index supplied by the f ilm manuf acturer)
           Lab Tools & Techniques
           Processing Inf ormation                 Pull processing - compensation f or ov er exposure of ECN f ilm by underdev elopment of the
                                                   chemical processing
            Shedding New Light on
            Darkroom Illumination                         Pull 1 = 2 minutes 30 seconds (150 sec).
            Antif oggant AF2000
            Negativ e Control Strips               push processing - compensation of under exposure of ECN f ilm by ov er-dev elopment of the
            Nanof iltration                        chemical processing

             Push/Pull Processing                         Push 1= 3 minutes 40 seconds (220 sec)
            Process Techniques                            Push 2= 4 minutes 40 seconds (280 sec)

            Sound Negativ e Perf orations          All processing conditions are to be operated @ 106F ( 41.1C). These Push / Pull conditions
            Shoreline Ef f ects                    are to be regarded as starting positions f or any laboratory . The times may be v aried to
                                                   achiev e LAD densities equal to the original normally exposed negativ e.
            Biological Growth (Slimes)
            Turbulation Guide                      Push Processing
           Processing Manuals
                                                   The f ollowing comments prov ide additional sensitometric inf ormation relativ e to the f ilm
           Storage                                 perf ormance as a result of the application of push processing.

           Transportation                          Push processing is achiev ed in the laboratory by reducing the transport speed of the
                                                   processing machine, thereby increasing the dev elopment time. Push processing is of ten
           Film Packaging Components
                                                   used to recov er density f rom under exposed camera originals. Ideally , the density loss f rom
           KEY KODE ID Numbers                     under exposure is exactly compensated by the increased density prov ided by push
           Technical Inf o Bulletins               processing. The compensation is not perf ect howev er, and the f inal result is ty pically higher
                                                   contrast images with a color bias and reduced photographic speed. Increased granularity is
          PSA                                      also a by -product of push processing. These ef f ects are generally independent of f ilm code
                                                   or emulsion dif f erences.
          Kodak End Credit &
          Sponsorship Logos                        Sensitometry:

                                                   Contrast:
                                                   Contrast build up f rom pushed processing is generally most dramatic in the bottom (cy an
                                                   and magenta) lay ers of negativ e f ilm and least dramatic in the top (y ellow) lay er. This is
                                                   because dev elopment is a dif f usion limited process. Contrast mismatch problems are
                                                   introduced with pushed processing resulting in high red to blue and high green to blue
                                                   contrast. The relativ ely high red to blue and high green to blue contrast of the negativ e
                                                   produces y ellow highlights and blue shadows in the print when mid-scale neutrals are
                                                   balanced. In many cases the y ellow highlights may hav e a red bias because the mismatch
                                                   tends to be higher in the cy an lay er compared to the magenta lay er. It should also be noted
                                                   that contrast mismatch v aries with exposure; stronger ef f ects with ov er exposure, weaker
                                                   ef f ects with underexposure. Under exposure, combined with pushed processing, tends to
                                                   lessen the ef f ects of increased contrast f rom pushed processing alone. Dif f erences in
                                                   exposure and scene content may hav e a signif icant ef f ect on the perception of color in the
                                                   resultant print, when pushed processing is used.




1 of 2                                                                                                                                              09/07/10 02:51
KODAK: Processing: Push / Pull Processing                                                http://motion.kodak.com/US/en/motion/Support/T ec...



                                                     Speed:
                                                     ER speed increases with Push processing may be signif icantly less than needed to of f set
                                                     speed loss f rom under exposure. With the giv en conditions abov e, Push 1 processing
                                                     produces ER speed increases of less than a 1/3 of a stop and Push 2 produces ER speed
                                                     increases of around 1/2 of a stop. Push 2 taken in combination with two stops of under
                                                     exposure represents a stop and a half loss in real speed. The end result is smoky shadows in
                                                     prints.

                                                     Granularity:
                                                     Regarding granularity , the f ollowing general comment is true: push processing increases the
                                                     granularity f or all f ilms. Further, it is apparent that under exposure also produces increases in
                                                     the granularity f or all f ilms. The combination of push processing and under exposure may
                                                     produce additiv e increases in granularity up to the extent of 10-12 units, compared to normal
                                                     exposure / normal processing. It seems probable that some customers might complain about
                                                     grain (and color rendition) when comparing under exposed , push processed originals to
                                                     normal exposure and normal processing conditions.

                                                     AMT:
                                                     AMT (sharpness) numbers decrease with under exposure with all f ilms. The combination of
                                                     under exposure and push processing produce lower AMT's compared to normal exposure,
                                                     normal processing. The loss in sharpness f rom under exposure may not be objectionable in
                                                     pictures howev er, because this loss may be compensated subjectiv ely by the apparent
                                                     increase in sharpness associated with the higher contrast f rom push processing.

                                                     Summary (Push Processing):
                                                     Push processing is not recommended as a means to increase photographic speed. Push
                                                     processing produces contrast mismatches notably in the red and green sensitiv e lay ers ( red
                                                     most) compared to the blue. This produces reddish- y ellow highlights, and cy an- blue
                                                     shadows. Push processing also produces signif icant increases in f ilm granularity . Push
                                                     processing combined with under exposure produces a net loss in photographic speed, higher
                                                     contrast, smoky shadows, y ellow highlights and grainy images, with possible slight losses in
                                                     sharpness.

                                                     Pull Processing

                                                     Summary (Pull Processing):
                                                     In a similar analy sis, pull processing combined with ov er exposure of ECN f ilm, produces a
                                                     noticeable improv ement in granularity , a reduction in ov erall contrast, a slight color bias
                                                     (y ellow shadows and blue highlights) with no perceptible change in sharpness.

                                                     References

                                                            Motion Picture Camera Techniques - Dav id Samuelson
                                                            American Cinematographer - Rod Ry an
                                                            Motion Picture Film Processing - Dominic Case prov ide general guidelines f or
                                                            achiev ing pull and push processing conditions to compensate f or ov er and under
                                                            exposures on camera negativ e f ilms. The f ollowing recommended conditions were
                                                            deriv ed f rom public domain inf ormation:
                                                            Eastman Color High Speed Negativ e Film 5293 by G. Kennel et.al., SMPTE Journal
                                                            Oct. 1982
                                                            Graininess in Motion Pictures, 1984 SMPTE presentation by R. C. Sehlin f or push and
                                                            pull processing of ECN f ilms.




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