Help reading development charts

Discussion in 'B&W: Film, Paper, Chemistry' started by sterioma, Oct 26, 2004.

  1. sterioma

    sterioma Member

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    Hello everybody,

    this might sound like a dumb question, but here it is anyway.

    I am making a basic speed test know how to best rate Tri-X with my equipment.
    Suppose that after the test I find out that I should rate Tri-X as 200 ASA.

    Now, how do I read a development chart for Tri-X? Should I follow the instructions for Tri-X at E.I. 200?

    I am a bit confused about how the "personal" rating of the film relates to pull/push processing.
     
  2. rogueish

    rogueish Member

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    If you expose TX400 at a 200 rating, you would indeed develop at a 200 rating. Once you are comfortable with that (ie your negs come out well and your happy) you can start experimenting by adjusting the time (say 6.5 mins instead of 7minutes).
    Just in case, have you seen the http://www.digitaltruth.com/devchart.html
    And has been said before "The only dumb question is the one unasked."
     
  3. bobfowler

    bobfowler Subscriber

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    Part of the test for your effective speed is determined by your developing technique. I would start with the suggested development times and make a seris of exoposures of the same scene at various EI's. Find the negative that comes closest to your desired result and make development adjustments from there. A lot will depend on the brightness range of the scene and your metering technique.
     
  4. titrisol

    titrisol Member

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    I concurr with bob.
    You have to decide what the standard development procedure is and then shoot a test roll, bracketing every 1/2 stop or so. Examine the negatives and then decide which is YOUR speed for the film.
     
  5. sterioma

    sterioma Member

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    I have started with TriX rated at 400 as per manufacturer recommendation. I have made a few bracketing exposures (a few also around Zone I as recommended by Ansel Adams).

    I will then develop using the 400 E.I. development times for my film/developer combo (TriX/Rodinal in this case).

    Now, suppose that I like the results of 1 stop more better. This would lead me to rate the film at 200.

    If I got your points, bob and titrisol, I shouldn't refer to the development charts anymore but use that development time as a starting point and make further adjustments from there. Is it so?
     
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  6. lee

    lee Member

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    I would be tempted to use the EI of 200 and then use the development chart and subtract maybe 20% from the published time. This is good practice with 35mm film.


    lee\c
     
  7. sterioma

    sterioma Member

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    Lee, would you be using the suggested development time for E.I. 200, or just shoot at 200 and use the development time for 400?

    Also, why do you say that shortening the development time is a good practice for 35mm? Is it something related to the grain or something else?

    I have just started developing my own BW and I am already fascinated by how many things I have to try (and learn!) :smile:
     
  8. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator

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    If you develop the film for some time (say, the manufacturer's recommendation for EI 400) and discover that the exposures that give you sufficient shadow detail are at EI 200, then in the future rate the film at EI 200 and develop for the time you used in the test, and ignore what the chart says about film speed.

    Film speed is about shadow detail. Development time is about contrast.

    If your negs are too contrasty at the time you're using, decrease the development time, and if they are flat, then increase the time, but the speed will not change significantly.

    With the same film/developer combination, you can change developing time and the film speed will be about the same, but the contrast will be different. Even though manufacturers' film development charts say that you can increase film speed by increasing development time, this is in general a myth, if you measure film speed in terms of shadow detail. To get a real increase in speed with a particular film, you usually need to use a different developer formula or a technique like stand development.
     
  9. davet

    davet Member

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    David Goldfarb has got it right. You need to decouple exposure from development time. Exposure sets shadow density, development controls slope (contrast). It may be that you find shooting at 200 and developing "normally" (recommended for 400) works for you. It may be that you need to pull 20% (probably a good place to start) or more, especially if you shoot high contrast scenes and want separation from shadows to highlights. It may be that you want to add development time, if you like the high contrast look. It will likely be that you have no single development time for this film. Consider exposure and development two independent controls, and experiment!
     
  10. lee

    lee Member

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    Lee, would you be using the suggested development time for E.I. 200, or just shoot at 200 and use the development time for 400?

    Also, why do you say that shortening the development time is a good practice for 35mm? Is it something related to the grain or something else?

    I have just started developing my own BW and I am already fascinated by how many things I have to try (and learn!)

    I would use the 400 time. Shortening the development time will help reduce the contrast somewhat and it will help with the grain to a certain extent. IMO, most of the times are just a little too long for normal photography. Plus, it gives you a place to start. Shooting the film at half of the box speed will give you more shadow detail and reducing the development by 20% should help tame the highlights.

    Experiment and have fun,

    lee\c
     
  11. hansbeckert

    hansbeckert Inactive

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    You are doing it backwards. FIRST you must determine the developing time for a typical scene. You bracket your exposures over about three stops, over and over again on the same roll. You cut the roll into thirds, and develop each piece separately, using a range of times. Once you have determined the right time, the correct exposure should be obvious.
     
  12. Howard R. Tanger

    Howard R. Tanger Member

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    No, No, No! "YOUR" method is backwards. First you test for the film speed that is best for "your" equipment then you test for the developing time. Check the writings of Ansel Adams, Minor White, Fred Picker and many, many others.
    Howard
     
  13. gainer

    gainer Subscriber

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    If you examine characteristic curves for a series of development times you will see that as time increases, the effective film speed increases and contrast increases. If you know the contrast index you want, you can select the development time to give you that contrast and you will have to take the film speed that results. If you know the film speed you want, you may pick the time that gives you that speed (if it is possible) and you have to live with the contrast index that gives you. Some say you can use a "compensating" developer to get both low contrast and high film speed, but don't believe it until you see the curves,
     
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  15. mikewhi

    mikewhi Member

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    Since the original poster quoted AA and Zone System tests, I'll answer with that in mind. Zone system tests go as follows:

    1) First, make a film speed test.
    2) Second, make a test to determine your Normal (N) development time.
    3) Third, make subsequent tests to determine N+1 and N-1 times at least. Possibly do N+2 and N-2 also.

    It sounds like you've already done the speed test. Your ASA setting should result in an exposure for Zone I that will read as .1 above film base plus fog (FB+F) on a densitometer. That is the definition of film speed. The developer and development time that you use will have little effect on the outcome, unless you go to some odd extremes. Just use a standard film developer for the recommended time for that film and the speed test will be accurate.

    To get the Zone I exposure, you set the meter at the manufactureres rating for the film. Find a surface that is of even texture and reflectance and illuminate it evenly. I use a large piece of construction paper from an art supply store that is as close to middle gray as I can get. I illuminate it with flood lamps while pinned up on a wall. Then I take a meter reading and stop down 4 stops, 'placing' the card on Zone I. I point the camera at it and focus at infinity so the card is completely blurred and any surface texture is not in focus. Then you make an exposure. Then close down 1/3 stop, make another exposure, close down 1/3 stop more and make another exposure. Open up 2/3 stop to get back to original setting. Open up 1/3 stop more and make an exposure, then open up 1/3 stop more and make another exposure.

    So, you end up with 5 exposures at the rated speed and 1/3 and 2/3 stop more and less exposure. If you feel it's necessary, you can make 7 or 9 exposures if you want to. I would do this if the film was real old or I knew my shutter speeds were off or the meter wasn't all that accurate\consistent. 5 eposures should be ok, but 7 is fine, too.

    For sheet film, I have a neat trick where I can get 6 seperate exposures on a single sheet of 4x5 film. If anyone wants to know how to do that, let me know. It's VERY handy come testing time and saves a lot of film.

    Develop the film with something like Rodinal at a recommended dilution and time. Don't vary greatly from the recommended time, but you don't have to stick exactly to it since you haven't done your own development time tests yet. Earlier comments about film speed varying based on development time are true, but only at greatly increased\reduced development times and it varies by film. The speed changes because at expanded development times the 'toe' of the film comes 'up' - if you plotted a characterisctic curve of a film at different development times, you can actually see the densities of the Zone I values increase as development time increases, but they don't increase a whole lot.

    The slope of the curve changes, too, thus the reference to contrast changing at different development times. This slope indicates the contrast index of the film. You really want to use a film that will increase this slope at increased development times and lower the slope at reduced development times. This is what gives you the expansion\contraction contrast control that is so important to the Zone System. As I understand it, a film like Berger BPF doesn't do this well, but a film like EFKE 100 (or Tri-X among others) will do it well.

    The whole point I want to make is that for the the speed test, don't worry about the development time too much, just stick to a normal time\temp.

    You asked if, after determining your personal ASA speed, what development times do you follow. Well, you have to test that yourself! That's the second major test of the Zone System. You don't follow standard charts anymore - you've stepped into the relm of customization and a level of accuracy where charts are useless. Charts? We don't need no stinkin' charts!

    My method of determining development time is to first determine what density range my paper is capable of handling (probably about 1.13 for food fiber paper). I determine this by contacting a calibrated density step wedge onto the paper and just counting the number of wedges that go from pure black to pure white and sutbract the 2 densities from each other. I will probably end up around 1.13 or so, but I hear it is more like 1.35 for Azo (which can handle a very large density range but is for contact printing only).

    If you add .1 onto 1.13, I get 1.45 so I know that the greatest density that any of my negatives should have, to be printable, would be 1.23 which would print as pure paper base white in the print. One stop lower than that is textureless white (Zone IX) and one stop less than that is white that starts to show texture (like the threads in cloth) at Zone VIII.

    So, the point of the film speed test is to determine a film development time that will take a Zone X exposure and will produce a density of 1.23 in the negative. Simple enough. Set up card\camera again as before. Meter card, upen up 5 stops and make a series of exposures. If you're using roll film, expose the whole roll. All exposures are at Zone X.

    Cut the roll up into 3 pieces and devvelop one piece at the recommended time\temp for this film\developer. Measure densities. If the density is greater than 1.23, develop the next strip for about 10% less time and measure again. Keep changing development times until you get a time that will produce a density of 1.23 in the Zone X exposures. It does not have to be EXACTLY 1.23 but should be close. If I got 1.19 I'd call that good enough.

    As soon as you have a development time that will produce a density that will print as a Zone X tone in the paper, then you've got your standard development time.

    As a check on the accuracy of this density, you can do 2 things.

    1) Photograph some Zone VIII subjects, subjects that should print as white but with texture, like fabric, snow, feathers, etc.
    2) Take a film speed test strip and print it on your paper of choice. You can enlarge the negatives to 8x10 and put the film strip in the carrier so that a clear edge is projected onto some paper. Do a test strip and determine the SHORTEST amount of time necessary to print the film strip edges (unexposed but fully developed) as pure balck. Set the enlarger at a height that you can write down and make note of the lens aperture. Write them down.

    Then, develop the Zone III subjects for your 'normal' time. Put a negative in the enlarger at the same 8x10 height and lens aperture and make a single exposure at the time it took to produce maximum black thru film edge. Don't do a test stipr now, just pop in the negative and expose for this time. If all your calibration is correct, the Zone III densities should print as a Zone III or very close to it. This will be the acid test of your calibration process above. If this comes out right, you now have your own ASA speed and development time that will produce negatives of a know density range that is calibrated to your paper. As you try different papers, you should print the step wedge again to determine the density range the paper is capable of. If suddenly some brand is only good for a range of 1.00, then your 'normal' negatives will be too contrasty for this paper. If you contact printed your 'normal' negatives on Azo, you'd suddenly find the prints being way too soft. In these cases, you'd have to re-calibrate your negative densities to the paper again.

    After you determine your 'normal' development time, you next have to after N+1 and N-1 negative development times. Basically, N+1 is defined as the time it takes to take a Zone III exposure and end up with a Zone IX density. N-1 is the time it takes to take a Zone IX exposure and end up with a Zone VIII density in the negative. If you need some explanation of this process, let me know.

    AFter I had done all these tests in the past, I knew that I could take a piece of Grade 2 Zone VI Brilliant paper and enlarge one of my negatives for 12 seconds and I'd always get a full-tone print, or at least a print that accurately reproduced the densitives in the negatives that I had created. That is because it took 12 seconds to create a maximum black thru the FB+F with my film with the enlarger at a certain height and the lens at a certain aperture. All tones above Zone I printed in relation to their densities above FB+F. So, if my negative had a Zone VIII density, it printed as a Zone III tone in the print with this 12 second exposure.

    Over time the Zone System has been refined and some of it's underpinnings have been argued over by those who are really technical and inclined to test a lot. But the above process works quite well, will give you a personal ASA speed and a set of negative development times that will create negatives tailored to the characteristics of your paper.

    Good luck.

    -Mike
     
  16. sterioma

    sterioma Member

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    Mike, this really made me laugh and reading your comments along with the other ones, I realised that this is indeed the case!


    Actually, I am still in doing it, since I have only made the Zone I test as recommended by AA in The Negative and I haven't finished exposing the whole roll yet. Unfortunately, since I am just an enthusiastic beginner, I don't have a densitometer, but I might be able to borrow a stop meter to measure the densities.


    I have a couple of questions here:
    1. How do you cut the film in the darkroom without cutting through a frame when you cannot see what you're doing? Would maybe make some useless exposures say around 12 and 24 frames be useful so that if you cut them no harm is done to the test?
    2. Can it be that developing only 1/3 of film gives different results than developing a whole roll?


    I do not print my negatives myself, I hope to be able to do that in the future (if costs and space in my house will allow). Therefore I still cannot apply all the tests you've so clearly detailed for the print.

    Anyway, I want to thank you for this clear and detailed post. I enjoyed reading it and I am sure it will be a reference for all the other beginners like me in this site.

    Stefano
     
    Last edited by a moderator: Oct 27, 2004
  17. hansbeckert

    hansbeckert Inactive

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    No, no, no. Speed is dependant on devlopment time. You MUST determine the development time FIRST before you can measure the speed. There is no question about this.
     
  18. hansbeckert

    hansbeckert Inactive

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    The reply from mikewhi is complete zononsense. 'The Negative' is almost total hogwash, at least for 35mm. For what reason did you turn to those old books for advice?

    You MUST determine the contrast needed first, and you don't have to measure anything whatsoever. No knowledge of fb+f is needed. You take a roll of film and BRACKET the exposures above and below the nominal exposure, using a 'typical' daylight scene. You repeat the same bracketed range several times on the roll so that any 1/3 of it will contain the entire range. For example, you meter your scene (a typical street scene on a sunny day will do, do not use an overcast day) and let us suppose the meter suggests 1/250sec at f/5,6. Record the meter reading for later use. You expose the entire roll of film, leaving the aperture at f/5,6 but running the shutter speed from 1/1000sec to 1/60 sec. You keep doing this until you have used the entire 36 exposures, but you leave the tongue out when you rewind the film. When you go to develop the film, load only the first 1/3 of the roll, leaving the remaining 2/3 in the cassette. Cut off the film leaving a small leader hanging out. Process this 1/3 roll at the recommended time. Repeat with the other parts of the roll, but reduce development 10-15% for second part, and 20-30% for the third part. Make prints using grade 3, not grade 2, paper or filtration. Select the development time which produces the best contrast for a typical sunny day street scene using grade 3. Do not change the filtration or grade of paper (yet). Adjust the printing exposure time so that the different negative exposures appear the same. DO NOT change the contrast. That ruins the whole test.

    Once you have determined the correct development time, you are now in a position to determine the speed. Since you recorded the 'nominal' exposure, you can now compare the prints made on the various exposures. The 'lightest' exposure that produces prints virtually indistinguishable from heavier exposures is the correct minimum exposure. In other words, if you cannot tell the difference between 1/250sec and 1/500sec (when you have adjusted the printing time so both look the same), but you CAN tell the difference between 1/500sec and 1/1000sec, then the negative which best represents the 'speed' is 1/500sec. It is quite unlikely that the negative chosen will be the one the meter recommended.

    If the correct minimum exposure is 1/2 stop MORE than the one recommended by the meter (a typical result for me) reduce the speed number by that amount. For example, if your ISO 125 speed film requires 1/2 stop more exposure than the meter indicated, set your meter at 100 or 80. THAT is your 'speed'. If the best negative requires 1 whole stop more exposure than the meter recommended, then set your meter to 50 or 64. If, on the other hand, the corect minimum exposure is LESS than the one suggested by the meter, then increase your EI for future use by the appropriate amount.
     
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  19. mikewhi

    mikewhi Member

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    Thanks. I'm glad you got the intended humor! Try reading thru The Thread With No Name for utter nonsense and maybe even a laugh or two.
    You can also eyeball Zone I densities using a .10 ND filter, a lot cheaper than a densitometer! Just place the ND filter over the clear film in between frames and see which frame most clsely matches this density. You'd be surprised at how accurate the eyeball is....or maybe not....but it works fine.
    I was thinking you would sacrifice an entire roll for the development time test, every exposure made at Zone X. Then, it doesn't matter if you cut thru the middle of a frame or not.
    Insightful question! Answer: no. People have been doing it for millions of years and it works out ok. If you shoot 36 exp., developing 12 frames in a 35mm tank will work fine and the developing action on the 12 won't be measurably different than on 24. Even if there is only 1 frame in the tank, only so much developer can touch the emulsion at a given time so it's not like there are developing agents standing in line waiting to find a silver halide crystal to attack. Good idea, though.
    Bummer. Here is another idea, then. And I know this works because I've used it, read about it (in those ancient history books) and taught it. Develop 1/3rd of the roll. When the film dries, take a newspaper and sit in a room with 'normal' lightling like mid-day sun. Don't let the warm sun make you sleepy - you must be alert for this part! Put the negatives over the newsprint. For a correct density, you should just barely be able to read the print thru the negative. I don't mean just barely be able to make out that there is something underneath the negative, nor should it be really easy to read thru. You should 'just' be able to read thru the negative. The develpment time that it took for this strip will be your 'normal' development time. And this is even cheaper than a .10 ND filter, heck if you find someone sleeping on the bus on the way home, it can even be free - except for larceny chagres and legal costs, of course.

    As for the printing time test, well whoever prints your negatives will thank you for the effort. Unless it's one of those infernal machines. But even it will find the negatives much easier to print.

    Have fun and let me know if I can help. If you want to, pm me and you can send me your negatives to read on my densitometer.
    -Mike
     
  20. hansbeckert

    hansbeckert Inactive

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    All of this is total hogwash. You don't need zones, and you don't need a densitometer. The only 'measure' of a good negative is whether it makes a good print.
     
  21. sterioma

    sterioma Member

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    Ok, now I understand your point and it make sense (I thought I had to bracket these exposures as well).


    This sounds easy! Will try that on a cloudless Sunday morning :smile:


    Thanks for your kind offer. I will PM you in case I need help with my tests!

    -Stefano
     
  22. modafoto

    modafoto Subscriber

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    You are right, but using a densitometer to check the negative you might learn something you could use in the exposure/development. That could lead to producing a negative that will give a good print. So you don't NEED it, but it might be useful...
     
  23. hansbeckert

    hansbeckert Inactive

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    It can help you maintain consistency AFTER you have established, through trial and error, what your standard time is, but it cannot help you to FIND that time. That is dependent solely on the printing quality.
     
  24. gainer

    gainer Subscriber

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    Ah, but if you use the densitometer with a step density wedge to determine the characteristic curves for a family of development times, you can find what you need in a systematic way. In fact, for most film-developer combinations two different development times, one of which is twice the other, will provide all the information you need to within government accuracy.
     
  25. lee

    lee Member

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    Hansbecket has used many names and has tried many times to control the forum that he jumps into. The moderator at photo.net has banned him several times and no one will argue with him on rec.photo. My suggestion is to not respond to anything he tries to say or no matter how he tries to tell you all how good he is. He has pointed us to images he made that are not particularly good but that is another story.

    lee\c
     
  26. hansbeckert

    hansbeckert Inactive

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    And how is that relevant to this thread?