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  1. #1

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    Film Speed/Developing Confusion

    Hello everyone,

    In reading books, threads, different web sites I have the following questions regarding establishing EI for the various films and camera's I have.

    1) How do you determe film speed since it is based on being able to develop film "in your normal way".

    2) I am transitioning from PMK, normal agitation, to Pyrocat-HD with agitation cycles at 3 minute intervals.

    3) Films I am testing will be:
    FP4 - 35mm, 120 (both in daylight tanks)
    FP4 - 4x5 in dip and dunk tanks
    Delta 3200 - 120 in daylight tanks
    TMY400 - 4x5, 8x10 in dip and dunk tanks, slosh trays
    PL100 - 8x10 in slosh trays

    I guess the biggest question I have is:without a "normal development time" how would you determine personal EI ?? I ball park development time in my understanding would give me the ability to read density (dont have densitometer) but wouldnt this density change if I also changed the development time also which to me would mean I would have to start all over??

    I have read about using the Stouffer Step Wedge too. My question with that is how do they determine the density's on it to compare the density's of my film with ?? Wouldnt different film have different thicknesses which would effect the density's I would compare to on my film??

    And lastly, once I have developed the film and determined some kind of density for film speed how would I determine if I needed to develop for longer or shorter times to get the optimum density or would I change film speed.

    I have read through the books The Negative by A.A, BTZS by Phil Davis and countless websites and they all (unless I missed something which is possible since my wife says I am blind) that film speed test, personal EI is conducted using your normal development techniques. Since I am changing developer and agitation which do I do first?? Use current film speed (personal EI) and get a development time and agitation cycle first, then re-do film speed test.


    Thanks for all the advice in advance.
    [FONT=Comic Sans MS]The Center for Desease Control just called. I have pegged the needle on their machines with this photography bug I have.[/FONT]

    Michael J. Taylor

  2. #2

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    There are several ways to determine your true film speed, from a similar post last week it seems that the View Camera Store will test your negatives and give you recommend times for your film and developer. You can also test without a desitometer by first testing your paper speed and developer then testing your film fist to determine your EI for shadow detail, then development times for highlight details. Post me if you want further details on self testing. I have not used the service provided by the View Camera Store but it seems like a real time saver.

  3. #3

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    The theory is that your EI is based on the low-density areas of the scene/neg, which are less dependent on development time than the high values (expose for the shadows, develop for the high values), so your precise development time shouldn't be an issue. Just use the manufacturer's recommended time for the EI test.

    Once you have your EI, you can then proceed to the development time test.

    Have fun!

  4. #4

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    I don't want to seem like a sales person for the BTZS, however, if you really want to know your materials, this is the most expeditious way to do so. As for Pyro, there are complications but I think Sandy King has found a way around them...

    With BTZS, you first calibrate your enlarger exposure by an appropriate setup that yields a fim speed of 100 from delta 100 developed with the tubes in d76 or xtol(don't have times/temps/dillutions in front of me) and plots the curves using a personal reference speed point in the plotter software. Once your exposure is calibrated, you can then adjust your light source via aperature or enlarger height so that a meter reading off the baseboard will yield the box speed of whichever other film you wish to test. So, for example, if you have a reading of EV4 for delta 100 you would adjust your enlarger to a reading of EV2 for a 400 speed film. Next you plot the curves of the tested films against the same PRSP in plotter. You will then know your true film speeds for various subject brightness ranges.

    OR

    Have View Camera Store send you the test negs using your film of choice, process them your normal way and return them to the VCS. They will in turn send you all of the data you need to get the perfect exposure in any light condition your film/dev combo can handle.

    hope this helps

    bob

  5. #5

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    Another factor that is a part of BTZS is that EI is not fixed but instead changes with changing SBR and hence development.

  6. #6

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    Without the use of a densitometer (haved searched under every rock and sagebrush in the surrounding area) I dont think I can follow the theories listed in the BTZS although I would love to. I guess I am stuck with the original zone system techniques.

    Paul, you mentioned testing paper first and then adjusting EI to fit into that paper speed range. Would this mean that I would have to do a film test for each paper that I will be using??
    [FONT=Comic Sans MS]The Center for Desease Control just called. I have pegged the needle on their machines with this photography bug I have.[/FONT]

    Michael J. Taylor

  7. #7
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    Try to find the Fred Picker book "Zone 6 Workshop". He has a fairly simple explanation of film testing, based on the final print. And he does not use a densitometer.
    —Eric

  8. #8

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    Same way I have alwas done it and other photogs for the past century. Pick a subject with detailed black and detailed whites. Expose for box normal, plus 1/2 stop, plus 1 full stop. Develope and print the least exposed frame that shows required shadow detail. Print the blacks properly and evaluate the whites ,adjusting the white density with development time as necessary. Small changes in time will not significantly change the shadow detail.

  9. #9

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    Quote Originally Posted by 2Ldude
    Without the use of a densitometer (haved searched under

    Paul, you mentioned testing paper first and then adjusting EI to fit into that paper speed range. Would this mean that I would have to do a film test for each paper that I will be using??
    Yes, I was taught this approach my one of my old NCOIC of the Air Force photo lab I was first assigned to in 1970. He used a Kodak print scale as a 10 step wedge, put a clear negative in the enlarger, stop down your lens to F 8 or F11 and expose your paper that has been cut down to fit the Kodak scale in 2 second intervals and then develop in your standard print developer at your standard time until you get a print that has all 10 gray scales which will approximate the 10 Zones, with the middle wedge at zone 5. If you use VC filter filter for grade 2 or 3. So when you test for film you always print at the same F/Stop and time that gave a full range test print. So you do need to test for each paper.

  10. #10

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    Thanks for all the help guys. I have alot better understanding now and a direction to go. I also went to home depot and found enough stuff to make the poor man's densitometer using the diagram in BTZS. What it didnt say was whether the reversed lens was stopped down or wide open, focused at infinity.... I guess I will have to trial and error that part.

    Paul, I also dug up a print projection scale for my enlarger that I will use for the paper test along with my negatives. thanks for the advice.
    [FONT=Comic Sans MS]The Center for Desease Control just called. I have pegged the needle on their machines with this photography bug I have.[/FONT]

    Michael J. Taylor

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