I understand what your camera repair person indicated to you about your meter not being linear (based upon time of day). I have never heard that before from anyone, anywhere. That would indicate that somehow the photocell would be affected by light color temperature or light intensity.
Light intensity, certainly. That is what meters must measure. But that would seem to indicate to me that your meter is not linear on shadow readings. But light intensity is light intensity irregardless of time of day. Now if he were speaking about reciprocity characteristics of a particular film that would make more sense. However, that is a characteristic of film and not of a camera.
If somehow the meter's photocell is not linear on color temperature that would indicate a faulty design by Nikon (I suppose that could happen)...if it were some other lesser known manufacturer I could more readily accept that premise. But Nikon???
I would wait and render judgement of the linear accuracy of the meter based upon your actual, in field, usage experience.
I also find what the guy in the shop said to be a little suspect. There are people who have 35 years of experience, and people who have a month's worth of experience 12 times a year for 35 years.
Meters often are non-linear, but it tends to be in the opposite direction from what the shop guy described. It should be accurate in full sun, but it might tend to underexpose in low light or when making stopped down readings.
Depending on the design of the meter, 0.15 volts may make a difference. Some cameras of that era had voltage regulated meters that would have no problem with a 1.5v battery, but many did not, and they would require an adapter, recalibration, or one of the Weincell Zinc-air batteries designed to replace the now illegal mercury batteries around which the camera was designed. It's worth trying a Weincell battery to see if you get better results, and then either stick with them (downside is that they don't last long) or consider having the meter recalibrated.
Also, meters of the age of the Nikkormat were indeed not linear for color temperature. That is why Nikon developed RGB metering and why Zone VI sold recalibrated Pentax Spot Meters to match the spectral sensitivity of Tri-X and similar films.
That said, I would agree with Donald, that you should base your meter settings on your own tests and field experience. That's part of the purpose of doing all the Zone system testing.
Well, OK! Just got my densitometer results back.
Film Base 31
5 min 15 sec 131
5 min 45 sec 132
6 min 15 sec 150
So it appears that 5 min 45 sec will give me negatives that will print with a 3 filter. I was very happy to see that relationship come up. <grin> Many sincere thanks to Dan and all of you!!!!
It would be nice to know the #2 filter time too but I can live very nicely indeed with this result.
Of course I also have the other roll of film wherein I shot a sequence of Zone 0 to Zone 11 twice. My next step is to develop that roll at 5 min 45 sec and then have the densitometer give me a read on each zone and plot the results. But for the plot to have any real meaning I believe I need to plot at LEAST at +n and –n roll of film. Isn’t that true, that I need some further reference plots to give me perspective.
With the info I’ve collected at this point I believe I would guess at how much +n add –n actually are. But what are reasonable guesses on time at this point knowing what we (I mean YOU all) know?
Isn’t it true that if I really want to know something here that I would run tests and plot the curve of my paper also? How does one plot the curve of their paper?
David measuring and segmenting the film into three was surprisingly easy so that would be the route I would take. I would only loose six or so frames and at $3.10 a roll that’s not much.
Your results look great. You are correct in that the 5 min 45 second development time should work on grade three paper (you may need to bump it to 6 minutes...but I would leave it at 5min 45 seconds for now). The 6 min 15 second development time will work on grade two paper with a diffusion light source.
To answer your question about the curve on your paper, by developing the roll that you shot with the 0-XI exposures and developed at your determined time you will have created a step wedge calibrated to your system. Taking the grade three filtration (in the case of VC paper) or grade three on graded paper and contact printing your negatives with the zone exposures you will be able to determine the tonal correlation of those exposures and their printed scale on that grade of paper.
You should have Dmax black on Zones O through I and you should begin to see the first tonal variance (though slight) at the Zone II exposure. Zone III will be noticeably lighter. Zone V should correspond to an 18% gray card when you have the correct enlarger exposure. Moving up the scale you should have tonal variance at each step until you reach Zone IX which should be only slightly less white then Zone X (after drying down the paper.)Zone X and XI exporsures should be base paper white.
As I mentioned before, by targeting your negative density to grade three paper you will be able to work your plus and minus situations through paper grade changes. I will repeat that the reason for this is that as developing time increases so does grain. With 35 mm that is an issue.
If you want to try your short roll modified development plan (which I really don't recommend), you can use your shorter and longer development times as your plus and minus (based upon your current density measurements).
Good luck. Let us know how things work out with the next step in this process.
Don, sorry I got your name wrong in a previous post.
Thursday I exposed a roll of FP4 to create a Zone 0 through XI. Friday I took it in and had a densitometer reading. My results were:
Base between frames 37
Zone 0 37
I wonder why the base is different between a clear frame and the clear portions between frames?
Now what I am to do, I believe, is contract print these on the paper that I use i.e. Forte, FB, Glossy. I am to see what I get and match them against an independent step scale. When they match then I will know that at that height and with that enlarger I will probably print a normal negative without much problem.
I would like to plot these values just for the experience. I went back into the Davis book but, sorry, I still find that very deep water. Is there an easier method to plot these values?
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First, subract the base + fog value from the readings, since you are only interested in image density, not the background density. Zone 0 will be 0.0, Zone I is .07, Zone II is .19, etc. if you are using .37 as your B+F value.
The reason that the space between frames might be different from a clear frame is probably due to normal sampling error, although it's possible that there really is greater density between the frames due to infectious development or some sort of adjacency effect. It's not a big deal.
Also, just so things make sense in terms of other things you might read, you should include the decimal point in your density readings. They are .37, .44, etc. through... 2.06. These are standard logarithmic units of density. A difference of .3 is equivalent to one stop. You'll notice that this is the same system that is sometimes used to describe neutral density filters--.3 is one stop or 2X, .9 is three stops or 8X, etc.
The easiest way to plot the values is to make a graph with the zones from 0 to XI along the X axis and the density values on the Y axis.
While you can compare a calibrated step tablet to your negatives contact printed on your photo paper, it really would serve no good purpose for your evaluation.
Instead it would prove beneficial to raise your enlarger head to the height and focused projection of an 8X10 enlargement and then contact printing your negative strips onto your chosen paper. When the proper exposure is achieved you will find that the Zone V value negative will correspond to the gray value of an 18% gray card. Don't concern yourself at this point with trying to match white values, print for maximum black, or any of the assorted and sundry methods that you have read or heard about. What we are trying to do at this point is to determine where the negative density values will match your paper grade. We will concern ourselves with determining proper print exposure after this is determined.
If you get your exposure of the 18% gray card and (Zone V) negative density contact to match then you will find that your low and high value densities will be accurately represented on the paper.
I can tell you now, that based on your exposure and your development time, this strip of exposures (as reported by your densities) will print most aptly on a grade two paper and a diffusion light source rather then the grade three that I would have hoped for.
That would indicate that you will have a printable negative, perhaps not quite optimum for 35 mm work, in my experience. The reason as I have previously stated is for grain considerations on the print, 35 mm will print a better image when the negative densities are such that they match a grade three paper.
When you have a contact of this strip of negatives on your paper, you should find black at zones I and II, marginally lighter on Zone III, progressively lighter until you reach Zone VIII and only marginally lighter (after drying the print) on Zone IX. The remainder of the upper zones should be base paper white.
If you find that your result differs then you need to adjust paper grade to create the final result, as described. Once you have completed this test you will find that in the future under similar and repeatable conditions that you will print a negative exposed the same way and developed the same way on the same grade of paper.
I would suggest that Peter might consider adjusting the ei downward a bit. .07 is close but no cigar. Maybe one half a stop. That should give enough of an increase in density at zone I to satisfy the .10 requirement.
Thanks Don. Now I know I’m going to show my ignorant butt. But allow me to see if I can rationalize what you said. The schools here by the way only have ‘condenser’ enlargers.
So you can see from the densitometer numbers that I will print best on grade 2 using a diffusion enlarger. If I understand correctly using a condenser enlarger I might indeed be able to print on grade 3?????
Originally it had appeared that calibrating my meter might mean that I’d turn my ASA all the way down to .32—it is of course presently turned to .68. So if I dialed in .50 (Does that sound right Lee?) on my ASA dial the film would be exposed slightly longer AND my development time would be shorter yet i.e. less than 5m45s.
This being the case then, roughly speaking, then my densitometer number would creep a little ways toward Zone IX or 1.43 from the present reading of 1.29 (using a base subtraction number of 35) and the same creep would occur in Zone V only a little less so because it is lower down on the scale.
But now I’m stuck. Why would increasing the density slightly of Zone VIII shift my printing to grade 3 i.e. if I’ve gotten it right to this point? What does the density have to do with the grade of paper? At grade 3 I have fewer steps of tone. I’m not sure how that correlates to a ‘density’.
I fully accept that you are right about grade 3 being the best place to print but I’m not sure I understand how I’d get there or why 1.1 indicates grade 3 if I am being at all clear.
Also, when I am contact printing my paper with these negatives do I use white light, lens stopped down two or do I put in a filter? It appears that I should use a #2 filter, right? Then I change times until I get a Zone V that matches the step chart?
Your conclusion about film, development and paper is exactly what I want to accomplish.
David, I will indeed plot my numbers. I will go ahead and try for some +n and –n times also after I finish the above experiments. I’ve only got two days left of school so I have to really use them.
Why does changing your zone VIII density change the grade of paper called for?--
The reason for measuring these densities in the first place is to enable you to match the contrast of the scene to the film and the film to the paper. A negative with a greater difference between Zone I and Zone VIII will have a longer scale and greater contrast, while a negative with a smaller difference will have a shorter scale and less contrast.
Donald's suggestion is, for 35mm, to make your negatives about one zone less contrasty than what might be considered "normal" (in other words, to use N-1 development as your normal development time) and to compensate by printing on a higher grade of paper--grade 3. The main advantage of doing this is finer grain, which is more important for 35mm than for larger formats.