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Thread: "True film speed" vs just developing the film more?

  1. #21

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    Re: "True film speed" vs just developing the film more?

    Aha ok good to know. Do you still need to meter for that (since how you meter would be part of this equation?). Could be quite the combination if testing the meter, the lens, the film, and the lighting.

  2. #22

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    Re: "True film speed" vs just developing the film more?

    You are on track. With BTZS, I'd recommend you make the necessary effort understand every bit of knowledge in the first half. The logarithmic math is essential because it's all based on that. Don't think you will have to use all that theory in practice, but by understanding well sensitometry you will be aware of what you are doing in any situation.
    ____

    Quote Originally Posted by m00dawg View Post
    Pancro 400 seems to work better more at 200
    Just acquire that knowledge, then you will know why 200 works better with the way you meter. With an spot metering you will know what density will have any that spot of the scene in the negative, if tonality is compressed there or not in that spot, and you will know what development require that sheet to craft the visualization you want, and if the negative will be easy to print. I encourage you to get that knowledge. Next step is to use that tool for aesthetics, this is the difficult part to me.

    That level of control is not always necessary, but exposing a LF sheet may require a remarkable effort, so nailing things is essential. With rolls we bracket on a doubt, this may be cheaper than thinking, but a photographer like John Sexton does not bracket, he rather makes two shots with same settings to have a backup, and he does it because he has all under control.

  3. #23

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    Re: "True film speed" vs just developing the film more?

    Quote Originally Posted by Drew Wiley View Post
    I'll stay on the sidelines chuckling this time.
    A wise decision!

  4. #24

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    Re: "True film speed" vs just developing the film more?

    I'll chime in again, on the side of simplicity, and offer another approach.

    I've managed to arrive at a high level of technical excellence when it comes to exposure and development without a densitometer or using higher math. Not that I can't do math or understand logarithms; I just don't need it to calibrate my film exposure and development.

    My approach is strictly visual and based on making a "proper proof" on the printing paper I use most (which, unfortunately changes every year now, but I digress...).
    Making a print with the minimum exposure to render the clear area (rebate) of the negative close to maximum black on the paper is the key. Make a print leaving a strip of the paper uncovered by the negative (contact print) or by leaving a bit of space beside the negative in the carrier (enlargement) that will receive more exposure than the area covered by the negative. Make a test strip, dry it down and inspect it in light that you consider optimum for displaying prints (this is critical; too bright and you'll end up underexposing and vice-versa). Find the minimum exposure that renders the black of the rebate almost indistinguishable from the black of the uncovered stripe. Note all your parameters (exposure time, f-stop, enlarger head height, etc., etc.). That's your "proper proofing time."

    Now, simply make a proper proof of a typical negative on your favorite paper, choosing a medium grade (2-3, or whatever gets you in the middle of your contrast adjusting possibilities) and evaluate. If shadow detail is lacking, you need to expose more (change your E.I.). If it is way up on the scale, you're exposing more than you need to. If the highlights are dull and gray, you need to develop more; if they're blown out blank white, you're overdeveloping. Make adjustments, make some more negatives and proper proof them till you get the results you want. That's it.

    You can refine the above for contractions and expansions, all the different films you use and all developers you use. Quick, easy, no investment in precision equipment (i.e., no densitometer), etc.

    I'm now to the point that when in the field I indicate which paper grade I wish to print on along with my development scheme (N, N+ etc.). I'm right on 75% of the time and only off by a grade the rest of the time.

    There are a lot more refinements you can make after this, but getting these basic things right right away makes your life a whole lot easier.

    I love reading about sensitometry and tone reproduction and I think it helps me with the nuances and details of the whole process; I just don't need it to find the right exposure and development for my films...

    Best,

    Doremus

  5. #25

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    Re: "True film speed" vs just developing the film more?

    Quote Originally Posted by Doremus Scudder View Post
    I've managed to arrive at a high level of technical excellence when it comes to exposure and development without a densitometer or using higher math.

    The recipe you explain is really very good advice, and it's completely worth to follow, there is a lot of wisdom in it.

    Using a recipe is perfectly fine, but if one knows well the theory then he also knows what the recipe is to work, when is to fail, and what to do insted.

    Making a film calibration was a basic exercise in photography schools for very good resons.

    About investment, my high precission Nuclear Associates (ex RX gear) was $20, or one can simply scan the Stouffer alongside the calibrations to compare with no additional cost. A lux meter is $15.

    It's a personal choice, one may want to learn the theory or not, but by spending a weekend one may experiment a boost in his mentality. At leat one knows why is he doing what he is doing.

  6. #26
    Drew Wiley
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    Re: "True film speed" vs just developing the film more?

    One can also buy a Calibrated Step Tablet, with each of the 21 steps already read on a densitometer and written down on the package. Then, for beginner purposes, one can do crude "visual densitometry". You take a sheet of opaque black cardboard and punch two small holes about 1/4" or less in diameter, several inches apart, using a paper punch or leather punch. The step tablet is ordinarily on a sheet of 4x5 film. You place the area you want to read in your own test negative under one hole, over a light box, then using the other hole, see which step on the official tablet most closely resembles the particular density on your own shot. I won't go into the whole procedure here, and only mention how you don't necessarily need to purchase an expensive densitometer just to get started.

  7. #27

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    Re: "True film speed" vs just developing the film more?

    Ah that's a good idea! I have a feeling in practice I'll be doing an amalgamation of all these, especially while I read the book - I don't plan on suspending all my photography until I figure all this out hehe.

    On the tablets, something like this? They are more expensive than I thought so was curious if I'm looking in the wrong place (prices are similar on the usual sites).

  8. #28

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    Re: "True film speed" vs just developing the film more?

    Quote Originally Posted by m00dawg View Post
    On the tablets, something like this?
    No!!!!

    http://www.stouffer.net/T2115spec.htm T2115, $7

    Or the calibrated one $17, T2115C http://www.stouffer.net/Productlist.htm


    You scan your negative alongside with the Stouffer and by comparing you have a densitometer !!!

    Also soon I'll release this freeware: https://www.largeformatphotography.i...ation-software to make it easier.

    You make the contact copies of the stouffer, you scan the stouffer and the copies, et voilą... you have the curves with a click. Just buy a $15 densitometer if you want absolute units for light, like in the kodak datasheets.

  9. #29

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    Re: "True film speed" vs just developing the film more?

    Oh haha that's MUCH BETTER!

  10. #30
    Drew Wiley
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    Re: "True film speed" vs just developing the film more?

    Yes, thank you. There are indeed very expensive step tablets on glass used to calibrate densitometers etc themselves. But a basic Stouffer 21-step tablet on film should be around $40 or less. I suggest buying a new one. Old ones might turn up a lot cheaper, but also might have significantly yellowed over time, making them hard to use.

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