Phil Davis homemade densitometer

[BobF]

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.

 

[Loose Gravel]

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.

 

[JHannon]

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...


John.

 

[Robert]

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?

 

[Loose Gravel]

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.

 

[Bruce Osgood]

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?

 

[DKT]

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?

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....

 

[BobF]

BobF

Unless you work for free,.... then buy a used one from ebay or the like. between $50 and $100. .

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.

 

[Robert]

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

 

[JHannon]

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?

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....

 

[JHannon]

BobF

Unless you work for free,.... then buy a used one from ebay or the like. between $50 and $100. .

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.

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.

 

[Robert]

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.

 

[mvjim]

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.

 

[mvjim]

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.

 

[bronicadave]

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.

 

[Robert]

The 102 right?

I found this:

http://groups.google.ca/groups?hl=en&lr=&ie=UTF-8&oe=UTF-8&selm=33479ae1.15085763@news.cinternet.net

and got scared off.