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Thread: Sensitometer For B&W Film?

  1. #11
    Greg Davis's Avatar
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    Re: Sensitometer For B&W Film?

    You guys should read his original post again. He is not looking for a densitometer to read film density. He is looking for a sensitometer to expose film density. Completely different machine and purpose.

    I use a Tobias Wejex I-W that uses a small incandescent bulb with nd and 80A filters to convert it to daylight. About a 1/2 second exposure time. There is one on eBay right now for $200, but you just missed one for $5. I show mine in this video:

  2. #12

    Re: Sensitometer For B&W Film?

    Quote Originally Posted by Greg Davis View Post
    You guys should read his original post again. He is not looking for a densitometer to read film density. He is looking for a sensitometer to expose film density. Completely different machine and purpose.
    Does he produce black and white films and does he have to measure any densities daily to ensure a consistent production?

    That is rather unlikely, IMHO. That's why I assumed that he meant a densitometer rather than a sensitometer. Sorry.

    Furthermore, the term "sensitometer" contains the word "meter", which refers to an activity of "measuring". I don't see that exposing grayscales on a piece of film involves "measuring".

    But: if you buy a sensitometer (sensitoexposer), just send me some normally exposed gray scales on my favorite film ... You could provide us all with it.

  3. #13
    Tin Can's Avatar
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    Re: Sensitometer For B&W Film?

    Good video Greg

    Quote Originally Posted by Greg Davis View Post
    You guys should read his original post again. He is not looking for a densitometer to read film density. He is looking for a sensitometer to expose film density. Completely different machine and purpose.

    I use a Tobias Wejex I-W that uses a small incandescent bulb with nd and 80A filters to convert it to daylight. About a 1/2 second exposure time. There is one on eBay right now for $200, but you just missed one for $5. I show mine in this video:
    sin eater

  4. #14
    ic-racer's Avatar
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    Re: Sensitometer For B&W Film?

    That is a great Wejex, thank you for showing the insides, now I want one. I have a small collection of sensitometers including the older "Black Box" Wejex, but I don't have that one. I'll have to keep my eyes open for one.

  5. #15
    ic-racer's Avatar
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    Re: Sensitometer For B&W Film?

    Quote Originally Posted by Daniel Casper Lohenstein View Post
    Does he produce black and white films and does he have to measure any densities daily to ensure a consistent production?

    That is rather unlikely, IMHO. That's why I assumed that he meant a densitometer rather than a sensitometer. Sorry.

    Furthermore, the term "sensitometer" contains the word "meter", which refers to an activity of "measuring". I don't see that exposing grayscales on a piece of film involves "measuring".

    But: if you buy a sensitometer (sensitoexposer), just send me some normally exposed gray scales on my favorite film ... You could provide us all with it.
    To use the sensitometer a calibrated step wedge is paced in contact with the film. Yes, without that part, the machine is useless.

  6. #16

    Re: Sensitometer For B&W Film?

    Quote Originally Posted by ic-racer View Post
    To use the sensitometer a calibrated step wedge is paced in contact with the film. Yes, without that part, the machine is useless.
    I've been thinking. I'm not a native English speaker. Everything takes a little longer with me.

    in the german large format forum a user has the idea to use a contact copy box with a flash. so he can control the iso, by power.

    he uses darkslides with holes to expose the stouffer card. so he has 3 different iso per step.

    i myself would like to use the enlarger for the contact copy. that should be enough. but with which exposure time?

  7. #17
    Greg Davis's Avatar
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    Re: Sensitometer For B&W Film?

    I would aim for a time of 1/2 second. That should be within a very controllable and repeatable time without reciprocity failure.

  8. #18
    ic-racer's Avatar
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    Re: Sensitometer For B&W Film?

    Quote Originally Posted by Daniel Casper Lohenstein View Post
    I've been thinking. I'm not a native English speaker. Everything takes a little longer with me.

    in the german large format forum a user has the idea to use a contact copy box with a flash. so he can control the iso, by power.

    he uses darkslides with holes to expose the stouffer card. so he has 3 different iso per step.

    i myself would like to use the enlarger for the contact copy. that should be enough. but with which exposure time?
    Enlarger exposure time can be problematic because many enlarger timers don't go below 1 second. Making a sensitometer is not that hard, but make very sure of two things. 1) The field on which the step wedge is placed is PERFECTLY EVENLY illuminated and 2) The level of illumination will not change from year to year, month to month or day to day.

  9. #19
    bnxvs's Avatar
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    Re: Sensitometer For B&W Film?

    Quote Originally Posted by Greg Davis View Post
    You guys should read his original post again. He is not looking for a densitometer to read film density. He is looking for a sensitometer to expose film density. Completely different machine and purpose.

    I use a Tobias Wejex I-W that uses a small incandescent bulb with nd and 80A filters to convert it to daylight. About a 1/2 second exposure time. There is one on eBay right now for $200, but you just missed one for $5. I show mine in this video:
    +100!


    I just wrote about it yesterday ... https://www.largeformatphotography.i...=1#post1536887
    If the topic author is interested (DIY), I can give more detailed descriptions of the device and place the sketch and photos.

  10. #20
    Lascassas, TN
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    Re: Sensitometer For B&W Film?

    Phil Davis in his book "Beyond the Zone System" 4th Ed describes adapting a Pentax Spotmeter to use as a densitometer. It is a good read on film testing.
    Bill Kumpf

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