What Kodak says about "C41 Push Processing"

Discussion in 'Film and Processing' started by steve_levine, Feb 1, 2004.

  1. This should add some fire to the fuel?
    Push Processing

    The following comments provide additional sensitometric information
    relative to the film performance as a result of the application of
    push processing.

    Push processing is achieved in the laboratory by reducing the
    transport speed of the processing machine, thereby increasing the
    development time. Push processing is often used to recover density
    from under exposed camera originals. Ideally, the density loss from
    under exposure is exactly compensated by the increased density
    provided by push processing. The compensation is not perfect however,
    and the final result is typically higher contrast images with a color
    bias and reduced photographic speed. Increased granularity is also a
    by-product of push processing. These effects are generally
    independent of film code or emulsion differences.


    Contrast build up from pushed processing is generally most dramatic
    in the bottom (cyan and magenta) layers of negative film and least
    dramatic in the top (yellow) layer. This is because development is a
    diffusion limited process. Contrast mismatch problems are introduced
    with pushed processing resulting in high red to blue and high green
    to blue contrast. The relatively high red to blue and high green to
    blue contrast of the negative produces yellow highlights and blue
    shadows in the print when mid-scale neutrals are balanced. In many
    cases the yellow highlights may have a red bias because the mismatch
    tends to be higher in the cyan layer compared to the magenta layer.
    It should also be noted that contrast mismatch varies with exposure;
    stronger effects with over exposure, weaker effects with
    underexposure. Under exposure, combined with pushed processing, tends
    to lessen the effects of increased contrast from pushed processing
    alone. Differences in exposure and scene content may have a
    significant effect on the perception of color in the resultant print,
    when pushed processing is used.

    ER speed increases with Push processing may be significantly less
    than needed to offset speed loss from under exposure. With the given
    conditions above, 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.

    Regarding granularity, the following general comment is true: push
    processing increases the granularity for all films. Further, it is
    apparent that under exposure also produces increases in the
    granularity for all films. The combination of push processing and
    under exposure may produce additive 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

    AMT (sharpness) numbers decrease with under exposure with all films.
    The combination of under exposure and push processing produce lower
    AMT's compared to normal exposure, normal processing. The loss in
    sharpness from under exposure may not be objectionable in pictures
    however, because this loss may be compensated subjectively by the
    apparent increase in sharpness associated with the higher contrast
    from push processing.

    Summary (Push Processing):
    Push processing is not recommended as a means to increase
    photographic speed with Kodak C41 materials. Push processing produces
    contrast mismatches notably in the red and green sensitive layers (
    red most) compared to the blue. This produces reddish- yellow
    highlights, and cyan- blue shadows. Push processing also produces
    significant increases in film granularity. Push processing combined
    with under exposure produces a net loss in photographic speed, higher
    contrast, smoky shadows, yellow highlights and grainy images, with
    possible slight losses in sharpness.

    Pull Processing

    Summary (Pull Processing):
    In a similar analysis, pull processing combined with over exposure of
    Kodak C41 films, produces a noticeable improvement in granularity, a
    reduction in overall contrast, a slight color bias (yellow shadows
    and blue highlights) with no perceptible change in sharpness.
    Fuji & Ilford have similar warnings on their web sites.But I
    suppose the PHOTO.NET film processing "experts" will disagree?
  2. EricM

    EricM Planet Eric

    Steve is referring to this thread, to bring anyone interested up to date.


    Why he is posting this common knowledge and claiming to add fuel to a fire is beyond me. These known results of 'gain for loss', with push/pull processing posted here, have nothing to do with him being wrong there.
  3. I like making quotes to. From the "Common Dreams Newsletter":
    The original term moron was coined by an American Psychologist in New Jersey during the early part of the century. Moron was added to the US version of the IQ test to screen out people who looked intelligent but weren't. A moron was considered to have an IQ between 50-75.
    I'm not aware you can safely decrease the transport time of a dip -n- dunk processor if it's the conventional hydrolic type (Kodak is obviously referencing a mini-lab roller transport), although if you tweak the flux capacitor just right..... I'm also wondering if this Kodak tech tip you dug out of their archives also had a 'Shirley' wearing love beads, ala 1970's reference materials. The comment about 'smoky shadows' in prints would indicate some films around, circa, 1980s as well since all the modern C-41 and E-6 films don't have issues with fog at a 1 stop push. VPS didn't behave well when pushed, and neither did VPH as per my personal experience with them, and this appears the technology level being addressed here - 15year old films. I've seen Kodak publications claiming PRN had less contrast than Portra NC as well.
    When you increase processing time you increase granularity and contrast, and when you decrease processing time you decrease granularity and contrast. Are we learning something here, or is there a point to this other than the part time 18yr old at Motofoto knows more about C-41 management than than you ever will.
    In regards to "Expert", which you put in quotes to obviously bring attention to the fact there's an inferiority complex at play, I used to be so good at judging our C-41 lines I didn't even need to run control strips because I could visually tell by looking at HD minus LD on a reference neg exactly where the plots lied visually. I then used to make bets with our C-41 lab rat and see if I could come within 2-3 points of the actual plot when he ran the control strip. I won about 2/3 of the time.
    Your continued claims that E-6 and C-41 films can't be pushed is like saying Boeing Corp. doesn't build airplanes, but just helicopters, and is really detrimental to giving proper advice in this forum. Given the signal to noise ratio of the Internet though it's not unexpected. It's one thing to have a disagreement, but some of us who have pushed a lot of film in our life times and worked at professional labs are really wondering if you are honestly this ignorant.
    Somebody else play with this guy....I have other things to do.
  4. I was given a Flexcolor processing kit by Kodak when it came out; in the 1970's. The Kodak C41 seminar then said to keep the temperatures the same; and decrease/increase the time; for a asa drop/increase. They also said that this a real slight decrease/increase in real asa; not like wild claims by B&W developing changes with radical changes being possible in asa.. My friends old lab either faked off the C41 processor; to add a time to the development. I have also heard of increasing the temperarure gambit; if many rolls are to be pushed at once. Today many labs just give their "push c41 customers" more attention; ie do exposure adjustments in printing; and fib and use the same C41 process. The C41 process was made to be a high temperature standard process; to shorten the development time. The older C-22 was alot closer to "normal" developing temperatures; required alot more time.
  5. Using color negative for aerial photo, I have had to push process 70mm portra 160 NC to get enough speed for short enough exposure times. Works excellent = no noticable loss in resolution & color-balance (the possible shift obviously being handled during the color-conversion done during scanning). Agfa recommend push-processing for their C41 aerial color-neg films when the speed is needed.
  6. I've been on duty tonight watching to see what's killing some late night back-up jobs on my AS/400's, so I've had time to do some research.

    I really hate kicking a dog when it's already been hit by the train, but I found the tech pub Steve was referring to. Here's a screen shot from Kodak's web-site, and the references he's making are from 1982/84 and in regards to Kodak motion picture film. So, we're talking about 20yr old film technology, and MP film at that.
  7. {Yawn} Sorry about that. Ok, what was I talking about again? Oh yeah...trying to stay awake here.

    Here's a screen grab from Kodak again. This one is their application matrix from Supra 400/800. Note sports fans that Supra 400/800 are somewhat newer technology than 20yr old MP film.
  8. As instigator of the intitial question on the other post "getting pushy" cross
    referenced within the post which has been corss referenced below, perhaps I
    can comment.......

    Peak Imaging offer a push service on C41 developing. Consumer labs do not
    because (I am told) they can not alter the development time on the automated
    machines which they use to process.

    I sent five films to peak imaging from my holiday, four were pushed C41 (3 x
    Reala, 1 x Superia) and one was standard (unpushed) Reala.

    The pictures came back varying in quality, The superia should have chucked
    in the bin instead, although I suspect that a lot of that was to do with me and
    not the method (tungsten / fluoro bulb colour cast, inability to hold steady on a
    travellator, not focussed correctly etc.).

    The pushed Reala stuff where exposure was OK had a slightly more
    noticeable grain, particularly in complex detailed areas but if I told you it was
    400 speed and not Reala 100 then you would not bat an eyelid.

    If you are really bothered then I can scan and post.

    Just to reiterate that within "Getting Pushy", some told me to throw it in the bin
    as it was "toast".... if I had done that then I would have lost some unforgettable
    holiday memories......
  9. Thanks Scott for correcting Steve's post.

    If all photographers shared Steve's aversion to experimentation, the world of
    photography would be a very dull place.
  10. EricM

    EricM Planet Eric

    Nicholas, I’m glad to hear that all was not lost, and that that thread with all it’s bantering was worth the various burns some of us received amongst the flame throwing. I came back a couple of weeks later asking so.
  11. The constant red herring I see in push process threads is shadow speed. Just because you can't get a dramatic increase in shadow speed doesn't mean pushing is useless. Getting the midtones and highlights where you want them is often enough, and if a little shadow detail goes AWOL it's generally not missed.

    Re: Kelly's assertion that labs fake pushes: Yup, I've seen it done, but if you hold the "pushed" neg up next to a normally-processed neg it's obvious--the mask is denser on the pushed film. If the mask densities match, somebody's got some explaining to do. And yes, I have made a scene in front of other customers before I left the lab for the last time.

    My experience is that Costco/Walmart/Drugstores are hard to make push, but independently-owned 1-hour labs mostly will.

    Notably, in my actual experience (not just theory) NHG II/NPZ pushed 1 and rated at 1200 looks less underexposed and grainy than either of the current 1600-speed films shot at 1200.

    Also, as more and more printing is accomplished digitally, cross-casts are less of an issue--in an enlarger they're unfixable; in Photoshop they're trivial.
  12. If you think you are getting something useful from 'pushing' go right ahead. Dream on.....
  13. EricM

    EricM Planet Eric

    ignore the troll ladies and gents
  14. Hi Nick, good to hear your pics turned out fine. You said there was roll of Reala developed normally. How did it compare to the pushed ones?
  15. Considering Kodak publishes push times it's hard to call push processing expermenting. Kodak's lawyers likely read everything long before we do and anything that might even be close to risky gets cut.
  16. Robert:
    Dream on....
  17. I should add that if you miss the correct exposure slightly (not sure by how
    much though) and / or are out of focus then the prints look cack, particularly if
    your image has loads of pale colour / white.

    However, I forgot to check the negs to make sure they had'nt cheated at the
    print stage... will do that tonight..... I may be eating humble pie tomorrow...
    fortunately I have broad shoulders....

    The stuff that was not pushed and processed normally by Peak Imaging (12
    pounds a go for 36 at 7.5" x 5") looked like Claude Monet had added the
    colour personally. Bear in mind however that all my previous experience is
    with Kodak approved CONSUMER (i.e. 6.50 for 36 exp's at 7" by 5")
    processing.... Despite the hiked expense I now use Peak Imaging as my
    standard lab.

    Perhaps Hans, you would care to guess "push" or "unpushed" to a selection
    of 10 unaltered (I do not have photoshop but I have a flatbed scanner) prints
    of my holiday...... this may put a stop to being labelled a troll.....

    By the way, I always carry some NPH 400 now, and some Superia "Super G"
    1600 in case I am really desparate. If I forget to take it out the fridge then I buy
    Kodak high definition (ISO400) which is even available in UK petrol stations
  18. "The stuff that was not pushed and processed normally by Peak Imaging (12 pounds a go for 36 at 7.5" x 5") looked like Claude Monet had added the colour personally."

    What does this mean? Incorrect colors ? I'm really intersted to get a good idea how your results turned out, as I was one who pushed for pushing in the original discussion.
  19. Dream on, dream on, dream on

    Dream yourself a dream come true

    Dream on, dream on, dream on

    Dream until your dream comes true

    Dream on, dream on, dream on

    Dream on, dream on, dream on

    Sing with me, sing for the years

    Sing for the laughter 'n sing for the tears

    Sing with me, if it's just for today

    Maybe tomorrow the good lord will take you away
  20. Sometimes it gets really comical... Oh yeah.
  21. I never suggested that you cant push color neg films,I only question why anyone would need to?As for chrome stocks,same question?This isnt 1970 ,film manufacturing has come a long way,and high speed emulsions are readily available.The only reasons to push any film,in my ever so humble opinion,would be to correct an exposure error involving a non re-shootable event.To create a special effect or to enable shooting in very low light,in lieu of faster film.The original question here was regarding using zone system type contrast/tonal expansion/contraction development by manipulating procesing times with chromogenic B&W films.I said that this was basically impossible for a variety of reasons,the main one being lack of labs that will alter development of C41 films.In my experience with pushed C41 the emulsion layers when layed out on a graph tend to criss cross,rather than create nice linear H&D curves.Again in my experience,this makes for crappy prints(your mileage may vary).
  22. Right... I am going to start a new post.... all have a sneeky peek at "Getting
    Really Pushy".

    That way the two threads tie together, and this thread can remain on topic.....
  23. EricM

    EricM Planet Eric

    Steve, come on man, how can you say all this within two threads? “I never suggested that you cant push color neg films,I only question why anyone would need to?” “Since the C41 process time & temp is written in stone, Id say no.” “I dont see what differnce exposure makes with film that gets the same time/temp every time in development?” “How on earth does one alter dev times with C41 materials? The labs I use,(Millers & North American)would laugh at the suggestion.” No one has suggested that you get “better” results with pushing. However, some films do look better pulled when over exposed, Provia 400 @ 160 pull 1, and similar method for Velvia 50. Some here have been in situations, repetitively, where you have no choice to shoot at 1250 asa with ambient house lights.
  24. EricM

    EricM Planet Eric

  25. EricM

    EricM Planet Eric

  26. Ah, Eric, I saw your Sarah McLachlan pics and I was wondering if you'd ever shot a Hip concert ... you dog. I think shooting Gord Downie's antics would be fun.

    Back to the regularly scheduled misinformation, courtesy of Steve and Hans....
  27. EricM

    EricM Planet Eric

    Andrew, he is fun on stage! Won't stand still though, hard to get him sharp.
  28. EricM

    EricM Planet Eric

  29. Steve, pushed NPZ performs much better than Superia 1600. I tried
    them side-by-side and it's like Paradise versus Grain City.
  30. The 'pushed' images look really poor...just as I claimed they would...
  31. Prior to my becoming a career commercial photographer,I worked in both motion picture & photofinishing labs in Los Angeles,Ca.During this time I operated cine type and dip & dunk processing machines,and also worked in quality control performing sensitometric analysis of LAD(laboratory aim density) strips.During this time I experimented with every color film available at this time.My tests included varying development time & temperatures,as well as conducting cross processing tests 10 years before this came into vogue.The conclusions were that pushing is never a viable alternative to using faster films.As I have earlier stated,unless the photographer seeks a "special effect".In commercial photographic illustration work,the goal is normally to strive for the greatest quality obtainable by the tools & materials used.This normally doesnt include playing around with developing to change "gammas".At the present time,I work as a wedding & portrait shooter.In this line of work,we dont compromise quality to be trendy or experimentive.You have to take what ever I say with this in your thoughts.In fact none of the wedding labs, or any of the custom labs I deal with will push or pull color negative films.This just isnt done.Even Kodak when it mentions Supra pushes,advises that many labs dont offer this service.As for changing the gamma of chromogenics in an attempt to use zone system techniques,I found that these films dont have reciprocating responses the way sliver based B&W films do.When TCN & Porta B&W first came out I was thrilled with the concept for wedding candid use.I tried both films with scenes with normal brightness ranges exposed at box speed.The results were less than thrilling though.I then found that by lowering the films speed,contrast could be increased slightly.However,with high brightness range scenes,the exposure latitude was terrible.(Normally with silver based B&W films as brightness range increases,latitude decreases).With the chromogenics,we were never able to reach a happy medium in regards to contrast control,unless the scene brightness was controlled and the contrast lowered by lighting.I eventually had several test rolls processed by a lab in NYC that offered push/pull service of C41 films.The results didnt acheive what we wanted either.Exposing for the shadows,and stopping development didnt halt the highlights from burning up.Again,your mileage may vary.
  32. There a three types of photographers who push C41 colour negative film :

    1) Photojournalists working in low light who need to rate their 800ASA films at a
    higher speed.

    2) Editorial and Advertising photographers who push film (often rated at box speed)
    in order to create a look that is subtly different from the mainstream.

    3) Photographers who mistakenly rate their film at the wrong speed.

    Steve, I think you have conceded as much.

    I wouldn't expect a wedding photographer (or his labs) to express much of an interest
    in push-processing - likewise a mainstream commercial photographer, shooting
    packshots, roomsets etc.

    But speak to any pro lab in a big city - a city that has its fair share of fashion and
    advertising photographers - and you will find that C41 push-processing is very
    common indeed.
  33. With digital(and photoshop) replacing film cameras in photojournalism & many illustration tasks.Im afraid pushing color negative films is limited to those that make mistakes in setting ISO & those that dont know any better.
  34. Agreed. One by one, the labs doing this sort of work are going bankrupt.

    But as I save for my 20,000 dollar digital back, I'm quite happy to spend a couple of
    hundred on the push/pull tests that will ensure that my next job looks just the way I
  35. Elliott schrieb:

    "But speak to any pro lab in a big city - a city that has its fair share of fashion and advertising photographers - and you will find that C41 push-processing is very common indeed."

    Perhaps primarily for the color distortion, contrast distortions, weak black or deep tones, and increased grain it provides.....
  36. EricM

    EricM Planet Eric

    Elliot, carry on and leave ‘em to it. I could cut and paste a few threads to demonstrate the contradictions in Steve’s post, as he’s back tracking here, and talking like he’s said all along that pushing film is available and possible. But my time isn’t even worth shoving humble pie down his throat.

    Hans, we were never arguing about the results of pushing. How would an armchair photographer know anyway? Get with it.
  37. Eric,I normally never personally address strangers online.However,in your case Id suggest a double dose of "Mydol".

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