Phil Davis homemade densitometer

Discussion in 'B&W: Film, Paper, Chemistry' started by BobF, Jun 5, 2003.

  1. BobF

    BobF Member

    Messages:
    205
    Joined:
    Sep 7, 2002
    Location:
    Pikes Peak
    Has anyone ever built and used a homemade densitometer as shown in Phil Davis's book Beyond the Zone System? He indicates it is more than adequate but I have never heard of anyone actually building and using one. I am only mildly interested in this approach and don't want to spend much to try it out.
     
  2. Loose Gravel

    Loose Gravel Member

    Messages:
    921
    Joined:
    Feb 28, 2003
    Location:
    Santa Barbar
    BobF

    Unless you work for free (in which case, come on over), then buy a used one from ebay or the like. It will save you allot of dorking around and when you are done with it you can sell it off. There are many available that would work better than BTZS that are between $50 and $100. Otherwise, borrow one. If someone you know has one, I'll bet they don't use it much.
     
  3. JHannon

    JHannon Member

    Messages:
    969
    Joined:
    Sep 7, 2002
    Location:
    Boston, MA
    Shooter:
    Multi Format
    I use my spotmeter with a reverse mounted 50mm camera lens for 35mm and a small light table with a sheet of black construction paper w a hole cut out.
    I did not build the stand but hand hold the meter.

    Since all I am looking for is the difference between fb+fog and the zone I neg etc I use the formula EV X 0.3010 to get the relative density.

    So if the fb+fog neg = EV 10 then rel dens = 3.01
    the tested zone I neg = EV 9.6 then rel dens = aprox 2.89
    Difference = 3.01 - 2.89 or 0.12.

    Close enough for my humble work.

    It works for me. I would buy a real one on Ebay but have never had much luck in winning anything on Ebay unless I decide to use those sneeky programs that snipe at the last few seconds... :smile:


    John.
     
  4. Robert

    Robert Member

    Messages:
    747
    Joined:
    Sep 10, 2002
    Which ones are available for $50 to $100? I start reading transmission, reflective, colour, this, that my head spins. Things start to go dark and I need to lay down-)) What models are good enough? What features to look for?
     
  5. Loose Gravel

    Loose Gravel Member

    Messages:
    921
    Joined:
    Feb 28, 2003
    Location:
    Santa Barbar
    Robert, I would recommend an Xrite, Macbeth, or Tobias, (there are others, but I don't remember the names) but I don't know exactly what you are using it for. I guess that it is for BW calibration. If so, you can do this with a single channel transmission type. If you use Pyro film developers, then it would be better to have a digital model so that you can still zero with the blue filter in place. I bought an Xrite 301 for less than $30, but it was sold as 'not working, as is'. I took a chance. It turned out to need a fuse, an aperture, and a bath -- so I lucked out.
    I'd stay away from old Kodaks or Westons. They work, but not as well. Wait for a digital unit that won't be perfect but okay for your use.
     
  6. Bruce Osgood

    Bruce Osgood Membership Council Council

    Messages:
    2,612
    Joined:
    Sep 9, 2002
    Location:
    Brooklyn, N.Y.
    Shooter:
    Multi Format
    I use my spotmeter with a reverse mounted 50mm camera lens for 35mm and a small light table with a sheet of black construction paper w a hole cut out.

    EXACTLY..... But why the reversed lens for 35mm? My experience is to shoot a Z-I and any other Zone I feel I may need on each roll of film and measure that/those entire negs. Does the reversed lens allow you to pick out a small area of the 35 neg to measure?
     
  7. DKT

    DKT Member

    Messages:
    504
    Joined:
    Sep 19, 2002
    Couple of other makers are Eseco and Heiland. I use an Eseco T85CD for E6, and a X-Rite 301 ...for film you need a transmission densitometer. The Status A filters are for E6, Status M is C41. With a color densitometer, you can use the visual (white) channel for reading b&w. I've been having some trouble lately with the eseco, think I need to send it in for a tuneup, so I'm a little hesitant to recommend it...the X-rite works great for b&w, but I'm reading control strips and figuring out density ranges on dupe negs mostly....

    I don't know if any of them would be available for those price ranges, unless you just got lucky. I think we paid over $1500 for the eseco....
     
  8. BobF

    BobF Member

    Messages:
    205
    Joined:
    Sep 7, 2002
    Location:
    Pikes Peak
    I do work for free as this is just a hobby and I don't want to spend any $ if I don't have to. I think $50 is not likely unless I get real lucky. I would guess that over $500 is more to be expected for a useable unit.

    JHannon - I am glad to hear that it has been useful for you but I am also wondering what you are using the reversed lense for as the book doesn't mention anything about it. Either a later edition of the book has more info or you came up with your own adaptation. Either way I am interested in what you did.
     
  9. Robert

    Robert Member

    Messages:
    747
    Joined:
    Sep 10, 2002
    Gives me an idea what to look for. A while back somebody was selling nothing but meters but I couldn't figure out what was what.

    Thanks
     
  10. JHannon

    JHannon Member

    Messages:
    969
    Joined:
    Sep 7, 2002
    Location:
    Boston, MA
    Shooter:
    Multi Format
    The reversed lens allows me to get closer to the negative. Otherwise external light may effect the readings. I also have a rear lens cap on it with a hole to prevent flare. The only reason I used a 50mm lens from a 35mm camera is that the size of the filter (49mm) is easy to couple to the lightmeter's threaded ring. I use this on 35mm, 120, 4X5 film....
     
  11. JHannon

    JHannon Member

    Messages:
    969
    Joined:
    Sep 7, 2002
    Location:
    Boston, MA
    Shooter:
    Multi Format
    Bob, this is just a hobby for me too. The part about using reversed mounted lens (I believe) is in the 4th edition of the BTZS book. Phil talks about another used that did this. I guess the lens element he describes in the plans is no longer available. I loaned out my copy so I can't give you the page number, but it is in the edition I bought new about 1 year ago.

    Since the lightmeter sits on a stand, you need to add a magnifier to get that close. Some people also use a series of +1,+2 lens filters to get the proper distance. You also need a way to baffle the light to a small spot. I use a rear lens cap with a hole drilled in it. I am just too lazy to build the stand so I hand hold it. The 35mm lens has a 49mm thread and the meter has a 40.5mm thread, so I bought a 49mm to 40.5mm adapter then a 49mm to 49mm coupler I think it is called a reversing coupler.

    I hope this helps please email me if you have any questions.

    I would love to own a real one but the Ebay scene is too dangerous for me. :smile:
     
  12. Robert

    Robert Member

    Messages:
    747
    Joined:
    Sep 10, 2002
    An old MacBeth sold last night on Ebay for about $40. I did some looking and it sounded like it would do everything I need but then I found something about it being totally unsupported [hey it's old] and if it needed service it would be good only for the dump. So the stuff is out there.
     
  13. mvjim

    mvjim Member

    Messages:
    84
    Joined:
    Apr 20, 2003
    Location:
    New York Cit
    You know guys - that most labs have these- at least the good ones do. And if asked , are more than willing to read your negatives for a few dollars. Just ask.
     
  14. mvjim

    mvjim Member

    Messages:
    84
    Joined:
    Apr 20, 2003
    Location:
    New York Cit
    You know guys - that most labs have these- at least the good ones do. And if asked , are more than willing to read your negatives for a few dollars. Just ask.
     
  15. bronicadave

    bronicadave Member

    Messages:
    7
    Joined:
    Sep 7, 2002
    Well Robert, that old Macbeth sold for $41 actually. I know since I bought it. The way I figured I couldn't loose. The seller says it is functional. If the lamp is bad that can be replaced. Calibration should be easy enough. Minor repairs to things like switches or power supply I can do myself. The only killer would be a failure of the detector which would probably mean the junk heap. But for $41 it seemed like a reasonable thing to try.
     
  16. Robert

    Robert Member

    Messages:
    747
    Joined:
    Sep 10, 2002