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  1. #1

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    reading negative density without a ...

    Is there a way to read negative density without a densitometer. For rating film speed, and development times. I suspect that a spot meter and enlarger will come into play here. I have a diffusion enlarger and a spot meter, but it does not accept attachments.
    A negative, can always be turned into a positive.

  2. #2
    L Gebhardt's Avatar
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    Quote Originally Posted by ilfordrapid
    Is there a way to read negative density without a densitometer. For rating film speed, and development times. I suspect that a spot meter and enlarger will come into play here. I have a diffusion enlarger and a spot meter, but it does not accept attachments.
    The book Beyond the Zone System has a simple looking setup that uses a spot meter and a light table. I haven't tried it, but think this would work fine. and give you about 1/3 of a stop accuracy. Some darkroom exposure meters, like the RH Designs Analyser, also can be used as densitometers.

    Used densitometers are going for a not much money these days on ebay, so you may just want to save some trouble and get one.

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    Loose Gravel's Avatar
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    I understand this can be done with a film scanner. If not, go with one from ebay. I got a nice one for $30. It was sold as broken, but it only needed a fuse.
    Watch for Loose Gravel

  4. #4

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    Quote Originally Posted by ilfordrapid
    Is there a way to read negative density
    without a densitometer.
    Ilford's EM-10 spot enlarging meter can be used.
    Calibrate against a step wedge. Dan

  5. #5

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    Quote Originally Posted by Loose Gravel
    I understand this can be done with a film scanner. If not, go with one from ebay. I got a nice one for $30. It was sold as broken, but it only needed a fuse.
    Any info on this approach? I own a nice film scanner and would love to be able to use it as a densitometer, too. Any special software?

  6. #6
    Lee L's Avatar
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    I've had very usable results using a Minolta Spotmeter M (that reads to 1/10 stop) and a diffused lightbox. I've also had good results using a diffused light source (a 5000K flourescent bulb in a reflector) and the film placed over the aperture of a Gossen enlarging attachment on a Luna Pro F.

    I don't know the procedure using a scanner, but I'd presume you need to start with a decent step wedge and software that allows you to set and maintain specific manual settings, i.e. no autocorrection of exposure, gamma, etc.

    Lee

  7. #7

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    Quote Originally Posted by ilfordrapid
    Is there a way to read negative density without a densitometer. For rating film speed, and development times. I suspect that a spot meter and enlarger will come into play here. I have a diffusion enlarger and a spot meter, but it does not accept attachments.
    FWIW, I use a cheap CdS cell and a digital multimeter. Details in this thread:
    Homebrewed densitometer

    Accuracy against a calibrated transmission tablet from Stouffer is good, and overkill for film development.

  8. #8

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    I've been using my Adorama spot meter with one of those cheap, battery-operated lights that you put on a wall in your closet, and push the dome to turn on. If you're careful, you can read density differences down to about a 1/6 of a stop (is it on 10 1/3, 10 2/3, or between the two?), which is plenty fine enough for basic film exposure ratings and development time tests.

    You need a piece of film that has been developed with no exposure, to give you your film base + fog reading. Then, it's just a matter of measuring the increasing density of sheets of film rated at different EI's, compared to your FB+F base.

    Seems to work well...

  9. #9
    Flotsam's Avatar
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    I seem to remember that there is an article on APUG that covers this.
    That is called grain. It is supposed to be there.
    =Neal W.=

  10. #10

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    Quote Originally Posted by ilfordrapid
    I suspect that a spot meter and enlarger
    will come into play here.
    The EM-10's non linearity and 0 to 100 dial are it's
    short comings. It does present a Very tight spot
    when used on the baseboard.

    To calibrate use a 21 step step wedge. To read,
    interpolate. Use a middle range as most negatives
    fall within a density range of less than 1.5.

    BTW, off eBay I purchased a Tobias TB+ in near
    new condition and with instructions and all the
    extras for under $80. Dan

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