Density Opinion

[tim atherton]

"I had no idea Dr. Henry's book was so valuable"

there are plenty of copies for sale from $27+ to $75+

[Craig Schroeder]

Richard... I couldn't recall reading the GE Soft White routine in Henry's book and pulled my copy out just now. I can't quickly find the calibrating info and can't locate a reference in the index that sends me there. Where in the book is it? Is this bulb quite consistent over varying voltages? It certainly runs against one's instinct that this could be accurate but I certainly have respected Richard Henry's thoroughness of technique. The book is a fascinating read and after some years, this has me reading it again.

[Richard Schlesinger]

I have found the book extremely valuable, and often wondered why I seldom/never see references to it. At any rate, in the 2nd edition, beginning on page 167 he discusses light meters and his correspondence with Hideki Kondo, Chief, Research Laboratory, Japan Camera and Optical Instruments and Testing Institute. And a bunch of other people, and outlines what he learned about light meters (a very great deal).

On page 177 he describes a set up for checking calibration of a 1* spot meter using a GE Longlife White Lamp Bulb 100V 1585 Lumens. There is a diagram of the setup. He suggests using an inexpensive simple voltmeter (Radio Shack $10 - $20) plugged into the other half of a dual outlet to check the voltage at the time of testing, and gives corrections if the voltage is below 114 or above 121.

I hope this helps. If anyone wants the whole business on calibrating light meters I can probably manage it - though I'm something of a Luddite and don't know how to do much more than e-mail on a computer. Seeing the price of the book now, I can understand not wanting to spend $121. On the other hand there is a great deal of still useful information in the book, even though his testing was limited to Tri-X Professional roll film. Just reading his methodology is an education!

[Richard Schlesinger]

I wasn't aware of the changes at GE, but it is not surprising. Thinking about it, given the setup described 29'2" from the bulb for the meter, I think I would fool around with different bulbs until I found one where my meter would read the 15 Richard Henry found at that distance. By definition, I think, one would then have a bulb putting out 1585? lumens and, checking the voltage as directed and using ND filters, voila, a cheap and easy meter check for both accuracy and linearity.

[Brian Ellis]

I'd suggest making two changes in the way you're conducting the tests though I don't know whether either will necessarily solve your problem.

First, using a black card isn't a good idea. In theory it shouldn't matter since in theory the meter takes the density of the card into account in determining your exposures so that you should be able to use a black card, a white card, or anything in between but in practice things don't work exactly as they should in theory. Use something closer to neutral rather than a black (or a white)card. A gray card is nice but not a necessity, if you can't find one use a piece of cardboard from a box or something else that isn't overly dark or white, just make sure the surface is smooth.

Second, I don't exactly understand how you're conducting these tests. Zone V doesn't usually enter into film speed and development tests (at least not as I learned the testing methodology). But apart from that, why are you testing for three different zones, particularly Zone VIII, simultaneously with your film speed testing.? The normal procedure, or at least the one I was taught, is to determine your film speed by exposing for Zone I only, processing for the manufacturer's recommended time, then after you've established your film speed do your development time testing based on Zone VIII only.

[Richard Ryerson]

Hey all!

Thanks for the great info. It's helped in my testing tremendously.

Everyone really seems to think the black card is the culprit here so I found my gray card and did some more tests this weekend. So I found the gray card, tested the full range again and resulted in densities that you'd expect to see. WOOO HOOO a breack through!

The EI 50 test for Zone I was .07 over FB+F so I tested from EI 50 to EI 25 again. Haven't developed those negs. But I will let you know.

I will try to answer the questions that posters asked of me. Sorry they arent directed back to the poster, there are a few and I am pressed for time here.

Why test FB+F, Zone's I, V and VIII? Well I am new to the Zone System and that was the recommendation in AA's The Negative (recent edition) The value as I see it is that it will show you where your normal time results. It will not affect the Zone I density.

Why is the FB+F density so high? In a nutshell, I believe this is due to the fact that it's roll film 35mm. I don't know the exact expected values for TMAX 100 / D76 @ 1:1. I do know that the smaller the format, the greater the FB+F densities. Large Format you may get .02, medium format you may get .1, 35mm I am getting .21

I don't think that I am cooking the negatives too long in the soup. I am using the recommend times of 8:30 @ 20C exactly. I know this time will probably change, but it wouldn't represent such a bad value for Zone I, unless they were cooked over night.

Thanks again all!

Rick

PS. Just to let you guys know, I didn't spend all my photographic time doing tests this weekend. We had a local event for the schools activities (we are having budget problems, don't get me started) They had bands, vendors, contests, water activities, and a lot more. At any rate, my wife and I went and had a great time. I was able to shoot about 10 rolls throughout the day. Haven't 'souped' them yet.

Just thought I'd point out that even though we look for the devil in the details, we shouldn't forget the big picture.

[Todd Schoenbaum]

Just a few comments:

I think Fred Picker did recommend using a black card (or a gray card in deep shade) for the Zone I tests as this most accurately reproduces the values of objects that will be placed at Zone I. The idea was that meters may not be consistent over a range. But, now that I think about it more this doesnt seem to be all that great of an idea as sometimes objects with an EV of 9 may be placed at Zone I, and other times objects with EVs as low as 1. Still trying a Zone I test on a white board in open sunlight might be pushing it.

As for the FB+F being so high, this may be due to bad film. I have seen this happen when film is exposed to high temperatures (this may be your doing or transport or shop storage).

Testing shutters: While it wont give you the exact times, the following may help tell you if your shutters are consistent across the board and between lenses. Shoot for Zone V at varying aperature / shutter speed combinations and then check the values on the densitometer. The closer the values are, the more consistent your shutters are.

Also when shooting your Zone I tests, it has been recommended that there be a few sheets of higher Zone values in the tank so as to avoid an excess of developer in the solution.

Best of luck