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After exposing a white card to Zone VIII and developing it, the densitometer gives me a reading of 1.32.
The clear part of the film reads 0.29
According to what I read in "The Negative - Ansel Adams" this reading is in the right place for a diffusion enlarger for Zone VIII.
Question:
Is the reading of 1.32 the one I use or do I have to subtract the clear film reading 0.29 from 1.32 which would give me the net density and use that one?
I always null my densitometer to the film base to minimize the number of mathematic steps.
If you enlarge/expose some film base to just black on paper (not 'blackest black") then, with the same settings put the Zone VIII negative in the enlarger, and cover half, you should get just off white if negative development was appropriate for your enlarger and paper.
As you know any exposure variation making the Zone VIII ngative will alter things significantly, so appropriate E.I. determination needs to take place first.
Interesting you would put this because I have just been watching a Fred Picker video where he shows something very similar.Quote:
Originally Posted by ic-racer
He mentions exposing the clear film to reach max black on paper and use that time. You mentioned "Just Black". Any reason why not max black
In spite of some common teaching, a scientific analysis of 'excellent prints' demonstrated they didnt all reach max black or whitest white.
I read the Picker book in 1974, i really did not understand film until doing the tests in the book.
In practical terms doing Picker's test, the paper can really suck up a lot of exposure before revealing its blackest black. This will cause the Zone VIII frame to print too dark and lead to the path of high contrast, overdeveloped negatives that will be difficult to print.
My experience with students is the tests in the Picker book come out better in a workshop setting with an informed instructor.
and I thought we want 35mm film leader to be very opaque
tested by looking at a light bulb
I can equate to the Z VIII printing to dark which is the reason I am going to do the tests again. You say Just Black which can be subjective of course, I was thinking of doing a series of patches and picking the one just before it maxed out
On some films, that unexposed and developed film base can be much denser than you would ever guess.
IanB,
Yes, I would recommend to zero out your densitometer on a piece of developed Zone 0 film before reading for either Zone I or Zone VIII. I use an entire frame or sheet, processed as I normally would, and read from the center area. This will minimize possible erroneous reading due to flare, uneven lighting across the card, etc. After zeroing out your densitometer, a good Zone VIII reading will be in the 1.25 - 1.35 range. Nowadays, I tend to push it into the higher end of that range because I print with cold light and today's VC papers can easily handle it.
Regarding the max black, what you're looking for is the black patch that looks the same as all the rest following it. You want to view this strip under whatever viewing conditions you use to judge your prints when doing actual printing. Fred advised folks to find what they thought was max black, then back off a step. Why did he say this? Because most folks were using too strong of a light when viewing the strip. What you want is a convincing black, not necessarily the most blackest black unknown to man.
i have read every published paper on bw film speed and analysis available from university library end the internet.Quote:
Originally Posted by Tin Can
I have not encountered that.
Could be because film dmax is almost never observed with a 21 step wedge sensitometer exposure of bw negative film.
Alan9940
Thanks for that, I will zero out the densitometer that way. I will also do what you suggested with the max black. I did try it last night without backing up a step but I just felt to my eyes the grey was a little on the dark side for what I would think of Zone VIII so backingup 1 step may just put me in the right area.
Photographer's judgement is needed doing the tests. I don't think reflection densitometry of paper is much help due to the myriad of things that can distort reflection densitometer dmax readings.
Picker's book offers a send-in transmission densitometer test for 0.1 log D of film. There is no similar offer to perform reflection densitometry of one's maximum black test.
Zero a densitometer to Zone 0 makes not much sense. Zone 0 has no definition in ISO, or is it defined anywhere in the technical literature.
Standard practice is to null the densitometer to film base of the same piece of film on which one will make the densith reading.
The point of zeroing out the densitometer on a clear area of developed film is to remove the base + fog density. And, by definition, a clear piece of developed film is Zone 0.Quote:
Originally Posted by ic-racer
Exactly how I have done it -- but I keep my ISO and development the same, so I only have to do it once for each type of film.Quote:
Originally Posted by ic-racer
You seem to have a quite high base density at .29, so only about 1.00 overall between your hypothetical target points. But that's the second problem, it's still all hypothetically Zone this or Zone that. Not until you make real world exposures and see how they actually print will this begin to gel. Trying to overthink it all in advance using a step wedge might land you somewhere in the ballpark, but isn't quite the same thing. I'm not against densitometers - I've spent many many hours plotting actual curves with them. But until you've secured a working marriage between specific film protocol and a specific paper protocol, it's going to remain somewhat ethereal.
Exactly -- see "Controls in Black and White Photography" by Richard Henry -- do your own tests. How you expose and develop film depends on what paper you are using -- and how you expose and develop it. Start by figuring out how to develop the paper first, and then determine the range of the paper -- using a step table, of course. Then expose and develop the film to match -- not vice-versa.Quote:
Originally Posted by Drew Wiley
And do your own tests. You are the prosecutor, defense attorney, judge and jury.
Versus being presumptuous enough to "instruct" others how to proceed, I will instead relate my own procedure. And before doing that, let me point out that Ansel Adam's Zone System procedure was quite different from that which is typically applied today. For example, it was quite different from what John Sexton practices. So, I'm careful about taking values that Ansel Adams relates in his books too literally.Quote:
Originally Posted by IanBarber
As to your question, I DO NOT subtract film base plus fog from densities that produce this or that zone on photographic paper. I want THE film density value that produces this or that Zone VIII or Zone VII exposure, and film base plus fog contributes to that density.
And, versus using someone else's density, I want THAT density that yields a Zone VIII that I like. (Not that someone else likes.)
But before I can do that, I need to know how long to expose the paper. That exposure becomes the minimum exposure that will cause a Zone 0 negative to print maximum black on my paper of choice. (Ilford VC WarmTone.)
But before I can create a Zone 0 negative, I need to determine the actual film speed of my film of choice. (Ilford HP5.) I establish film speed by determining the ASA that renders a Zone 0 exposure density that is 0.1 density units above film base plus fog after developing the film at the manufacturer's recommended time and temperature. So, it's only to determine film speed that we subtract film base plus fog. And, we obtain a Zone 0 exposure by taking a light reading of a surface, and then selecting a shutter speed/f-stop combination that makes that surface five stops darker.
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In reverse order, I first determine the film speed of my film. Invariably, it tests out at half the manufacturer's recommended ASA, which would be ASA 200 for HP5. (Since Ilford recommends shooting HP5 at ASA 400.)
Knowing the film speed, I can create a Zone 0 negative by photographing a homogeneous, flat, light gray surface using an exposure that's five stops darker than that recommended by the light meter.
Next, I can use that Zone 0 negative to determine the minimum enlarger exposure needed to produce maximum black on my paper of choice. There are different ways to determine when one has reached maximum black on the paper. Basically, it becomes a judgement call.
Once I determine the enlarger exposure time, then I can produce a Zone VIII negative, and see how light or dark it prints on my paper of choice. Of course, I will need to pick a time at which to develop that negative. So, what is called the "Normal Development Time" is that development time that renders a Zone VIII negative that prints a Zone VIII shade of gray that you like on your paper of choice. By selecting a Normal Development Time that you like, you have tailored the Zone System to your needs, versus to someone else's needs. Note that I always develop paper in Dektol 1:1 for three minutes at 70 degrees with no VC color filtration. I'm sure you have your own preferences in this regard. What's important is to always use the same development time at the same temperature.
For myself, I use that process to pick a Zone VII negative that I like, versus a Zone VIII negative. I find that a negative with density of 1.35 density units prints a Zone VII shade of gray that I like on my paper of choice. So, I select a Normal Development Time that gives me a Zone VII negative with a density of 1.35 density units. (The longer the Normal Development Time, the higher the density.) Coincidentally, this is very close to the negative density that John Sexton likes for rendering a Zone VII density. (At least, liked at the time that I attended his workshop.)
Indeed a slope (contrast) yields the same result if one includes film base in the readings or not.
Of course speed determination, by definition, is independent of film base density.
As mentioned previously, there is no film rating system based on Zone 0, though, there is no law that says one can't make up whatever they want and post about it.
It was probably already answered, but you want net density, i.e 1.32 minus 0.29, the latter of which is quite high, by the way. That gives 1.03. For me, that's too low. I prefer a net density of about 1.25-1.3 for my Zone VIII.Quote:
Originally Posted by IanBarber
When I taught sensitometry, we would compare the Ansel Adams, Fred Picker (super simplified Adams approach) and The Beyond the Zone System methods by Phil Davis. FWIW, the variations in readings from a white card when used for determining development time and the number of variables can lead to some significant variations. Picker made a career out of special meter modifications to combat some of these issues as an example. Now, that said, the fastest and most reliable method were always the BTZS tests using a densitometer, stepwedge and controlled development. Among a typical class of 10-15 students, it was common to find a 30% variation (about one N number for Zonies) in development times using the white card and meter method. On the other hand, variations with the step wedge and BTZS methods were often less than 10% and the variation was always traced to agitation variations as all other variables (dilution, temps, etc) remained the same.
Just a thought....
I did the test again, exposing a white card to Zone VIII and developing it for 7 1/2 minutesQuote:
Originally Posted by Peter De Smidt
I placed the FB+Fog frame under the densitometer and zero it out.
My Zone VIII patched Read 1.08
I haven't printed the patch yet mainly because I feel the reading is still too low.
The leader leader which has obviously been exposed to daylight measures 2.12
Would you increase the dev time to see if I can get more density in the Z VIII patch
Or there is the school of thought that the negatives tonal relationships can be "compressed" but paper needed to expand the tonal relationships will require a higher grade, or more Blue filtration if VC. Others aim to get all their contrast on the negative and plan for Grade 2 paper. And all of this needs to be determined based on the subject being photographed and it's contrast. I fall somewhere in the middle these days but still lean toward a flatter negative, and grades 2.5-3 on a warmtone glossy paper.
I suggest taking multiple shots of a natural scene you would typically shoot , well metered so you know the tonal range, develop a negative to see how close you are in matching those relationships, then printing. Adjust development and measure again.
Based on the way I work, I'd suggest increasing development time by about 25%, depending on the film. If you're using TMax stock, that much increase may not be necessary. When I get a reading such as yours, I try to increase development time such that I either hit the range dead on or go slightly above; in other words, surround what will be your "correct" time, then extrapolate from there. For example, if 7.5 mins reads 1.08 and, say, 9.5 mins reads 1.5, then start with 8.5 mins and adjust from there. Stop testing at this point and go make images. If you need to tweak your EI or development time from there, your prints will tell the tale.Quote:
Originally Posted by IanBarber
Yes. Do what Allan suggests above.Quote:
Originally Posted by IanBarber
Thanks for all the replies, I am am now armed with lot's of valuable information :)
Here is X-Ray that needs more development
I like what happened, I was testing times
https://live.staticflickr.com/65535/...e3e6657e_z.jpg3 810 2-1 Macro by TIN CAN COLLEGE, on Flickr
Not to muddy the waters too much, but I use an approach similar to esearing's: I like to print with a setting on my color head (Chromega) of 30-40M or a skosh higher, which is about a #3 filter. I often make negatives with more contrast than would fit on the paper at that setting with a straight print, but then burn down highlights, etc. slightly with the 170Y setting (#00 filter if you like) till there's some tonality and then bring up detail in those areas with 170M (or #5 filter). In other words, I'm intentionally using too-contrasty paper and doing split-grade burning (and dodging at times) to make things fit. I find this gives the mid-tones more presence. I think a lot of prints made from negatives that "fit" the paper grade are just boring, tonality-wise...Quote:
Originally Posted by esearing
Best,
Doremus