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  1. #1

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    Speed Increasing Dev Question

    When using a speed increasing dev (like DD-X mentioned recently in another thread), I'm assuming this "underexposes" or underdevelops the negative a given amount, similar to pushing film speed. Am I correct in this assumption? If this is correct, would I then need to further overexpose the film (i.e. adjust film speed by the same amount in the opposite direction) in the camera? Thanks.

    Jmal

  2. #2
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    A speed increasing developer like Acufine or Microphen lets you expose the film at a higher speed than the box setting (i.e., it lets you "underexpose" in camera, but you're not really underexposing, because the speed is really higher), but still retain good shadow detail and normal contrast at the reduced exposure.

    This differs from what people normally call "pushing" (attempting to increase film speed substantially by extending development time), which usually increases density in the highlights while not really improving shadow detail significantly, and film speed is measured in terms of shadow detail.
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  3. #3

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    David,

    I think we're on the same page; I was just a little sloppy in my terminology. So, if I shoot Tri X at 200 normally, with a speed increasing developer, I could shoot it at the 400 box speed and get the same exposure (assuming the dev increases speed a full stop)? Yes?

    Jmal

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    David A. Goldfarb's Avatar
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    I wouldn't necessarily compare it to what your other developer is. I find I can get a reliable EI of 800 with TX in Acufine, and 640 with TXP, for instance.

    Better just to develop the fim in your speed developer of choice and test it on its own terms.
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  5. #5

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    Thanks. I'll start with the suggested times and work from there. I'm always looking for the easy way, but...Thanks.

    Jmal

  6. #6

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    Quote Originally Posted by jmal View Post
    When using a speed increasing dev (like DD-X mentioned recently in another thread), I'm assuming this "underexposes" or underdevelops the negative a given amount, similar to pushing film speed. Am I correct in this assumption? If this is correct, would I then need to further overexpose the film (i.e. adjust film speed by the same amount in the opposite direction) in the camera? Thanks.

    Jmal

    ISO film speeds are defined by the minimum exposure to give a fixed density at a given contrast. This varies according to the developer: the same 'ISO 400' film, in different developers, might range from ISO 200 (or less) to ISO 650 or slightly more. There is almost no limit to the speed you can use, but one full stop is usually the absolute limit you can gain.

    Most (not all) manufacturers use a 'middle of the road' developer such as ID11/D76 for speed determination. Use a speed increasing developer and you will get more genuine speed (and bigger grain); use a finer grain developer and you will get smaller grain, but less speed.

    Extra agitation also gives a small but measurable increase in true film speed.

    Many people confuse ISO speeds (scientifically determined and replicable) with EIs, or exposure indices, which can vary quite widely according to subject matter, lighting and personal preference.

    There's an entire free module on ISO film speeds in the Photo School at www.rogerandfrances.com.

    Cheers,

    R.

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    Roger,

    I guess in a roundabout kind of way I'm trying to figure out where to start with DD-X. After the positive comments in the other post, I decided I wanted to try it. I have been shooting 35mm Tri X (in HC-110 dil B or H) at EI 200 and cutting development a bit based on the light conditions. I arrived at this EI with no particular scientific testing, but rather trial and error. It seems to give a little better result than the box speed. I'm at a point where I've used D76 and HC-110 enough to have a good idea how they work and I'm still intersted in toying with others. I do need to stop at some point and pick something for consistency (though my results have never differed greatly). If I had to choose today, it would be D76, but I want to try the DD-X and see what I think. Anyhow, I have a couple of rolls with some potyentially good shots and I don't want to blow them. At the same time I don't ever shoot things that aren't meaningful to me, so I never have a junk roll to experiment with. I know it's a false economy to gamble with the good rolls rather than spending a few bucks on a test roll, but I feel risky. Also, I've never had any rolls come out unprintable, so I imagine I'll be okay just using Ilford's times. Any other advice for DD-X is appreciated.

    Jmal

  8. #8

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    Quote Originally Posted by jmal View Post
    Any other advice for DD-X is appreciated.

    Jmal

    Okay: here's a bugger. Ilford often give EI dev times for their devs, so DD-X @ 400 with an ISO 400 film will almost certainly be slightly low in contrast (I've not checked this with them but I do know about the EI trick. Their view is that it avoids confusion.

    If I were you I'd give 10 per cent OVER the published Ilford time for DD-X (or split the time between 400 and 800). This should give roughly the ISO contrast/speed point and thus (by definition) the ISO 650+. This is what I do, but I then rate the film at 400-500 with a spot meter, giving myself +1/3 to +2/3 stop, where I prefer the tonality.

    Hope this helps. As you say, it's unlikely to be unprintable in any case.


    Cheers,

    R.

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    Roger,

    Thanks for the info. However, as I shot at EI 200 I'm not sure it applies. Ilford gives a time of 6.5 minutes for EI 200. Should I split the difference between 200 and 400? Or, add the same percentage listed above to the 200 time? Thanks.


    Jmal

  10. #10

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    I use DDX for Tmax 3200 35mm. I shoot at 1600, duilte 1:5 rather than 1:4 and devleop at 3200 times, gives me good shadow without blocked highlights. I find it diffcult to get true 3200 speed with DDX or Tmax, at least for my equipment. For most 400 speed films I would try 200 at 1:5 at 400 times as well for a starting place. If you have access to a densitomer you can get a very percise EI.

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