Film speed testing question using waybeyond excel sheet

Discussion in 'B&W: Film, Paper, Chemistry' started by padraigm, Jan 31, 2013.

  1. padraigm

    padraigm Member

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    film graphs2.png Hi All,

    Need a little help here. I am using Ralph Lambrech's spread sheet to determine my film speed.

    A 21 step wedge was contact printed Hp5+ at f/8 .7 seconds in Xtol 1:1 @20c for the 4, 5.5, 11, and 16 minute intervals.

    Could someone who is familiar with this procedure look at my graphs and tell me what is wrong? I am thinking my exposure is still too short as I am missing too many data points in the shorter development times?

    I have a macbeth TD500 and I zeroed using the instruments light source. A calibrated step wedge indicates measurements are accurate.

    Any help would greatly be appreciated.

    Thanks


    film graphs.png
     
    Last edited by a moderator: Jan 31, 2013
  2. pawlowski6132

    pawlowski6132 Member

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    Wow. When did photography become a freakin science project?
     
  3. Kirk Keyes

    Kirk Keyes Member

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    Since 1890, when Hurter and Driffield invented sensitometry and densitometry.
     
  4. Kirk Keyes

    Kirk Keyes Member

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    I've not used the spreadsheet you have, but it looks to me that you don't have enought exposure on your 4 min time for the sheet to calculate a valid gradient. Note that the 4 min point on the time vs. gradient graph is way up above the over points off the graph. It looks like that point is calculated to equal 1.90 gradient. We all know it should be less than the 5.6 min gradient.

    I suggest rerunning the 4 min test and give the film about 4 stops more exposure to get more steps in the wedge to have usable density.
     
  5. Bill Burk

    Bill Burk Subscriber

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    Looks like your 8 minute time came reasonably close to what I call normal, the curve that most closely fits ASA specifications. Since the spreadsheet shows that near 0.62, that confirms your test is sane.

    As Kirk says, 4 stops more exposure would help for the 4 minute test. Next time you do a complete series, I would give 2 stops more exposure to all.

    Of course it would have been better if you could see all the data in the highlights. But for darkroom printing, you only need to see what exposures gives you highlight densities around 1.00 to 1.20. You have enough information to make informed decisions about how long to develop your film.

    Apart from the 4 minute test, the rest of the gradients look good.
     
  6. pawlowski6132

    pawlowski6132 Member

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    Hmm. Someone forgot to tell 99% of the brilliant photographers past and present.

    The above is totally unnecessary.
     
  7. Stephen Benskin

    Stephen Benskin Member

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    That's right people. You should know that by now. It's YOU push the button, KODAK does the rest. Duh.
     
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  8. pawlowski6132

    pawlowski6132 Member

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    Sorry

    You're right. ,sorry people. Fluency in chemistry, sensitometry, electrochemistry, etc is a prerequisite to producing great photographic art.

    I'm so stupid. My apologies.
     
  9. sehrgut

    sehrgut Member

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    tl;dr: stfu, pawlowski

    Pawlowski, without people that treated photography as "a freakin science project", you would have NO materials with which to make your own images. No one is claiming that everyone needs fluency in all the scientific disciplines impinging on photography to create great photographic art. What is necessary for anyone to create great photographic art (or workaday snapshots) is that some practitioners have that fluency, to enable the production and improvement of materials.
     
  10. padraigm

    padraigm Member

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    Kirk, Bill and everyone else thank you. Even you pawlow, haters gonna hate. I figured that was the case with not enough info in the 4 min development data set. Smoothing out the curves helped. I am finding I need way more exposure that what has been typically posted to run tests like this. I must say it's quite easy and fast once you have an exposure that works. The data pretty much came in line with what I came up with prior to having a densitometer. It's nice to see the + and - also in one go. I am primarily going to use this for alternative printing in the future and want to have some sort of "quantification" so as not to waste expensive materials. Thanks again.
     
  11. Kirk Keyes

    Kirk Keyes Member

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    Some people like to go beyond the basics. Nothing wrong with that.
    :smile:
     
  12. pawlowski6132

    pawlowski6132 Member

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    Been there, done that. I thought it was necessary. I wish someone would have enlightend me like tried to do for the OP.

    So, I guess I hate all my friends because that's the advice I give them.
     
  13. CPorter

    CPorter Member

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    Yeah, that's stupid alright...................troll.
     
  14. pawlowski6132

    pawlowski6132 Member

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    Your such an idiot. Why don't you read what I wrote.


     
  15. Bill Burk

    Bill Burk Subscriber

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    pawlowski6132,

    You are no dummy. Nor a troll. I've read your posts before and they are thoughtful. Maybe you have been recently upset by some personal remarks, hope you can let it slide.

    I get the feeling that in your heart you wish people could "feel" exposure and development in their bones, that it is all that is needed to solve their problems. And I would say you are right.

    I cannot tell you how many years I knew the phrase "expose for the shadows, develop for the highlights" by heart without "getting it". I developed by time and temperature to the charts with ISO speed and without changing times from published data. I got really good negatives all along. Once in a while a thin frame was useless and it bugged me that I really didn't "know" what I was doing. Some really "important" shots of mine are just impossible to print. It's those bad negatives that drive me to want to control film.

    Before I did a bit of testing, I never really learned to "feel" what it meant to expose sufficiently and develop for the right amount of time.

    True, nowadays I do more testing than necessary. But that's one of my pleasures.

    Many artists are frustrated by their medium, pencils don't draw what is in your mind without experience. Photography is special, you can get results quickly without really spending years of practice. But soon you reach a point where you don't get what you wanted. When you are frustrated and yearn to learn enough to regain the confidence that you had from the onset of your interest. This is where I believe the the Zone System (and it's corollary - film testing) base their appeal.

    Many introductions to the Zone System state that by the end of the course, students will learn in a very short time what usually takes years of experience to acquire. I believe that.

    So although it is hard work. Once it is done a student has made years of advancement. It's hard to tell how much time people will save in an Internet forum like this. Maybe it will take a year reading threads like these before a quick word helps show someone the light.

    True, one need not do testing. So, padraigm, you have done a lifetime's worth already and you might get some value by developing another 4 minute sheet. But after that, you are ready to go back out and shoot.
     
  16. CPorter

    CPorter Member

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    I originally took your posts as being seated in troll-like sarcasm, it appears I was grossly mistaken, so I offer you my apologies. The concept of idiocy is uniquely associated with human beings, I regret that I had such a moment, but can't be for certain it will be my last.
    Chuck