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Thread: Minimal Agitation Negative versus Tray Processed Negative

  1. #21

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    Re: Minimal Agitation Negative versus Tray Processed Negative

    Steve,
    It may be more helpful to show the density for the same four points on each image . Base/fog density, Highlight densitity -BF, shadow densitity-BF, and a midpoint-BF.
    This might show that there is only slightly more/less separation between the points.
    If not, what does that tell us about overall density and its effect on midtone contrast? Is having the thinner compressed negative enough to allow you to expand contrast more while printing, than is a thicker negative which may have more contrast already built in.
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  2. #22
    Jac@stafford.net's Avatar
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    Re: Minimal Agitation Negative versus Tray Processed Negative

    Quote Originally Posted by Pere Casals View Post
    Another way I used is to place some vertical sticks in the tray (with hot glue) in order the sheet cannot move, as it is retained by the sticks when rising a side to agitate.
    Great idea, and perhaps add two horizontal rods to minimize vertical movement?

    My old favorite was Honeywell Nikor Rocking Print Trays, for large film. It's worth a Google search. Excellent for maintaining temp and for minimal (if you wish) chemistry.

    Heath made one with a more severe curve, perhaps to minimize sink space.

    Click image for larger version. 

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  3. #23

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    Re: Minimal Agitation Negative versus Tray Processed Negative

    With vertical sticks it worked perfect... but I agitate gently...

  4. #24

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    Re: Minimal Agitation Negative versus Tray Processed Negative

    Yup...the old "canoe" tray - great memories! Also great for saving chemicals...but not so great for EMA!

  5. #25
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    Re: Minimal Agitation Negative versus Tray Processed Negative

    Quote Originally Posted by Pere Casals View Post
    With vertical sticks it worked perfect... but I agitate gently...
    I understand, and on second thought cross-bar sticks might introduce new turbulence. Thanks for the correction.
    .

  6. #26
    Steve Sherman's Avatar
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    Re: Minimal Agitation Negative versus Tray Processed Negative

    Quote Originally Posted by Pere Casals View Post
    Perhaps problem is the thought that a sensitometric calibration explains all. It is true that sensitometry explains very well how a regular photographic process works, but with Pyro + EMA we are talking about compensation, and IMHO this is more complex, as (with EMA) response is also dependant on local exhaustion of developer and also on local bromide concentration that also influence local development. I mention the concepts I think I understand, but more can be there...

    I was thinking that perhaps Pyro has an advantage for EMA, as density is partially built with stain then less bromide is generated for building the same density, with less risk of bromide streaks... just a thought. Also Xtol, for example (IIRC) is less prone to restrain development from byproducts... Perhaps that delicate equilibrium is needed to obtain a sound result....
    Yes there is a very delicate equilibrium which must be maintained between strength of developer, frequency of agitation and length of agitation to actually produced Adjacency Effects. The Pyro stain is important to a degree but not as important as Pyro developers in general are "tanning" developers and therefore harden the film's emulsion within the first few minutes in solution. That is the main reason why long periods of development time can be tolerated where as with non Pyro developers there are a number of short comings when the film remains in chemistry for extended periods of time. Think of the EMA technique in this way, Dilution allows Time to be extended, Time allows Infrequent Agitation when these three components in processing are in delicate balance, only then will the developer exhaust, and only then will Adjacency Effects happen. Very simple, to increase Adjacency Effects increase the amount of time the developer has exhausted before a new agitation cycle begins.

    Compensation or compression of highlight densities is much more about dilute developer than a trait exclusive to Pyro Chemistry.

    Hope this helps clear things up.


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  7. #27
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    Re: Minimal Agitation Negative versus Tray Processed Negative

    Quote Originally Posted by Steve Sherman View Post
    [...]not as important as Pyro developers in general are "tanning" developers and therefore harden the film's emulsion within the first few minutes in solution. [...]
    Harden. I'm not sure what it means. Does it apply to the whole emulsion, or does it vary with density caused by greater exposure? Thanks for any insight.

  8. #28
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    Re: Minimal Agitation Negative versus Tray Processed Negative

    Quote Originally Posted by John Layton View Post
    Steve...any comments about how EMA might (or would) work with brush development? The reason I ask is based on my current setup - with six 5x7 developer trays enclosed in a single 20x24 tray (other solutions batched in single trays). My developer agitation routine has involved tilting the 20x24 tray around...which works great except I will sometimes get some "micro scratches" on a film's base as it moves about its tray - so my next move is to either very gently lift and flip each negative in succession...or go to brush agitation, either of which would offer the further advantage of tailoring agitation to each negative.

    As my routine involves doing six single developer trays at once...you can see what compels me to adapt this to EMA. And I've examined a few of your negatives up close (with a loupe) when I last visited...and yes indeed - they show a nice balance of smoothness/sharpness with wonderful micro contrasts, with resultant prints likewise...and exhibiting no hints of "over manipulation." So I am feeling very motivated!
    Hello again John, you are one of the few active members on this LF forum that has actually seen my negatives and can speak to the differences you've seen, and of course the resulting prints.

    So, I believe your 6 individual trays in one 20x24 tray is for the purpose of developing multiple sheets at one time to economize on time processing film, that seems to be a constant with those who pursue the EMA technique. First, the micro scratches you speak of could be happening the film holder just as easily as the tray, I get micro scratches now and then but as long as they are on the base side they really don't show up in the printing stage.

    Here's how I see the Plus and Minuses of the Tray versus EMA Tubes.

    Tray Pluses, 6 sheets in a 30-40 window, brush development would work with a Pyro chemistry as has been explained earlier, Pyro developers in general "tan" the emulsion or harden the emulsion very early on in the processing time, first 2-3 minutes ( no hardening fixer required, it's a waste of money, and the ammonium present in a hardening fixer will serve to make the film's emulsion more brittle over time) However, I see brush development of 6 separate sheets of film as more inconsistent than a rotary action.

    Tray Minuses, 1 ) Greater aerial oxidation and not as easy to replicate from one session to the next, i.e. darkroom humidity and ambient temperature must be more consistent than a closed tube. 2 ) separate trays in 20x24 tray, process must be done in total darkness 3 ) there is a decent chance that one or more sheets will float to the surface of the developer and become mottled from lack of complete coverage, remember total darkness 4 ) With approx. 35 sq. in of open surface of developer exposed to oxidation Pyrogallol based developers such as PMK, ABC, Rollo, Wimberelys are OUT, developer would oxidizes in seconds. Even, PyroCatechin developers such as PyroCat would be more susceptible to rapid oxidation.

    EMA Tube Pluses 1 ) tightly controlled oxidation rate as there is virtually no air space between the tube and cap. 2 ) Agitation is done in a rotary manner much the same as Jobo and possibly more consistent than rocking 3 ) When processing with up to three separate tubes, the film goes in approx. 4 minutes apart, and therefore comes out with only one sheet in fixer tray with less chance of scratching, again in darkness for the first 90 secs.

    EMA Tube Minuses 1 ) The most I can processes in a 40 minute window is 3 sheets, the new Tube design has cured all other short comings of my previous method IMHO.

    Joh, I'm likely bias when it comes to the Tube method, but at the same time this is the ONLY way I have processed my film for the past 14 + years and have continued to tweak the formula that was successful back in late 2003. Thanks for commenting and continued success with your EMA workflow.


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  9. #29
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    Re: Minimal Agitation Negative versus Tray Processed Negative

    Quote Originally Posted by esearing View Post
    Steve,
    It may be more helpful to show the density for the same four points on each image . Base/fog density, Highlight densitity -BF, shadow densitity-BF, and a midpoint-BF.
    This might show that there is only slightly more/less separation between the points.
    If not, what does that tell us about overall density and its effect on midtone contrast? Is having the thinner compressed negative enough to allow you to expand contrast more while printing, than is a thicker negative which may have more contrast already built in.
    This is the age old argument that building contrast into the negative is the way to create greater Mid Tone Contrast. While that thinking still has a strong hold today, it should have gone by the wayside the minute THICK EMULSION FILMS no longer existed. Only when emulsions have a significant thickness to them did that thinking bear fruit. Not to mention the Silver rich papers that were available in those days when hand in hand with those thick emulsion films.

    Today's thin emulsion films respond wonderfully to Pyro base developers due to the tanning effect, look at a conventional negative in "glancing light" and you'll see a smooth uniformity of surface across the entire sheet of film. Hold a Pyro processed negative up to glancing light and you'll see an ecthing or layering effect across the varying densities across the surface of the film. One reason acutance is palpable with Pyro developers, and that effect is heighten when using and EMA form of film development.

    With all due respect, the real numbers than mean something to me is the Eye Test, and when I look at prints that I make today from negatives I exposed and processed 20 years ago with the best option of the day back then, Tri-X and HC 110 developer the difference is not slight, it is striking. The Mid Tone separation is greater, but what jumps out is how harsh the 20 year old negs look when compared to the way I design negatives for EMA processing with PyroCat HD.

    Lastly, I no longer build contrast into the negative, thats' one reason why my highlight densities are so low. I like to say I build Tonality into the negative and then build Contrast in the printing process.

    Thanks for commenting Eric !

    Cheers, SS


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  10. #30
    Steve Sherman's Avatar
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    Re: Minimal Agitation Negative versus Tray Processed Negative

    Quote Originally Posted by Jac@stafford.net View Post
    Harden. I'm not sure what it means. Does it apply to the whole emulsion, or does it vary with density caused by greater exposure? Thanks for any insight.
    That's a very good question, I can't say for absolute but my gut tells me the hardening process comes to completion at some point. I believe it may take longer with an EMA type of development but in end, say 5 minutes rather than 2 minutes the entire emulsion will be uniformly hardened.

    Thanks for reaching out


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