Zone 1 placement?
Jim made an interesting comment about the placement of zone 1 at 0.1 above film base plus fog in the "Victoms of the Zone System" thread by Chuck1. While I know this is the conventional wisdom with respect to the location of zone 1 (BTZS and ZS), I have had a similar finding to his. For the actual use of film, he states that zone III should be placed at closer to 0.4 above FB+ fog for any real use of shadow values.
I'd been trying to balance film with azo paper, on and off for a year and a half, and am finally having some success. One large problem has been the selection of film speed. I'd been beating my head against the rock, trying to figure out how claims for full film speeds and full shadow values could be made. After doing film tests which were useless for actual print making, I have come to the conclusion that tests should be done to give exposure which is far above the "normal" amount of light if shadow detail is to be of any real use in a print on azo.
I suspect my stubborn use of Efke 25 for azo has been a large part of my self-imposed frustration. I have finally settled on asa 6 as my "normal" film speed for grade 2 azo. Fortunately, Efke 25 is very long on contrast (up to 3.0 with some developers). If you look at the data on J&C's site, you can see a toe which goes well up towards 1.0 before it gets to the straight line portion of the film. Since I don't have a densitometer, I don't have actual numbers to go by. This finding for shadow values has been verified by in a similar manner (step wedge testing, FP4+) with different films and has shown a departure from the conventional wisdom as well.
I'm wondering if this is peculiar to azo and tests, or if others under rate film this much as a rule? What about alternative process, are there similar findings about exposure and shadow values? Thanks, tim
A Zone I density of 0.1 is really just a starting point. If you can get enough shadow detail that way, then you'll get more room to play with at the highlight end of the curve, and the thinnest acceptible neg, which will also be the least grainy. If you're not getting enough shadow detail that way, then it's reasonable to increase your working EI, but keep an eye on the highlights, to make sure you're not losing anything at that end of the curve.
I expose Efke PL100 at 50 and place significant shadows on Zone IV. Like you, I don't have a densitometer, but I'm sure this would put Zone I significantly above .01. I've only used Azo since I began exposing this way.
What Jim and Noseoil are really talking about is shadow placement and not film speed. If you're interested in film speed, I happen to have an article in the current issue of PHOTO Techniques that deals with it. It's titled Flare and Accurate Film Speeds. My premise is the discontinuity between the ISO speeds and speeds from Zone System testing originate from a fundamental misconception within Zone System methodology. If you follow the traditional ZS method of film speed testing, you will produce speeds more in line with the pre 1960 film speed standards. One of the basic premises of the article is that the film speed point isn't necessarily the point of desired exposure, but only a point to define the film speed (explained in more detail in the article). Consider, Zone I is four stops under the meter reading or meter calibration point, while the ISO speed is determined at 3 1/3 stops under and also assumes a certain amount of flare. That's a 2/3 stop difference between the two methods.
Stephen, If I run Efke 25 at asa 6 and place shadow values at zone 4, where am I with respect to film speed? Since I am already giving 4x more light than is "standard" with this film by way of speed, are you suggesting that I am giving the film an actual rating of 25, then overexposing by 4 stops, or a 16 fold increase in light?
Seeking a clarification here, as I really don't understand why setting the meter at asa 6 is not a film speed setting of 6. If I run all of my exposures at that setting and then place shadows where I deem fit and develop for highlights, isn't this an accurate representation of film speed? Need a little help here, please, as I must admit that I have been known to set the meter at asa 3 when doing N- at times.
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Couple of things, while you can calculate film speed by the .1 method with the BTZS, it is usually done by CI which IMO is more reliable.
Originally Posted by noseoil
Now, your apropriate film speed is also determined by the paper you use. For example, in my film speed and developing test using the BTZS with Pyrocat HD and TMY as well as Ultrafine (knock off Ilford) I got full film speed but since pt/ pd compresses the tonality so much when printing, I cut the speed in half, effectively moving all the values up on the curve one stop. So for me, "zone III" is actually 0.6 to 0.7 as opposed to the "Adams" values of .3 to .4.
Azo has a very good DR, in fact far better than pt/pd but from what I understand MAS develops his negatives to be very dense, which leads me to believe Azo might be in the same boat as pt/pd, since it has such a long range, perhaps using higher density values for the shadows might be a good thing.
IMO the object of testing, either by the ZS or the BTZS is not to obtain the thinnest possible negative with all the information, but to obtain information that will allow you consistently produce negatives with the desired information in them. With roll film it is important to get the thinniest possible negative to reduce grain, we dont have that constraint with LF.
I guess it's a matter of how someone defines film speed. To me, you are talking about exposure index which can be interpreted as a personal choice for the speed setting and not about the actual film speed. I also assume the reason why you set your EI to a lower than indicated speed setting is to give you a safety factor. I can't see you actually printing the shadow up around Zone IV. IMO, simply changing the EI doesn't really change the Zone placement. The relationship between the tones don't change. They are simply pushed up the curve. Then the higher densities of the negative are printing down. My idea of the Zone System is to visualize the tones of the final print when shooting, so when you "place" a value at a particular Zone, it's not a particular density on the negative, but a relative value on the finished print.
I've attached two three quadrant reproduction curves that illustrates difference between "normal" exposure" (Graph 5) and giving the film a little extra exposure and printing down the additional density (Graph 6). As you can see, there is very little difference.
So, there's nothing wrong with what you are doing. I was just commenting more on the connotations of certain terms.
Generally when we speak of "film speeds" we are talking about exposure index, the only people who can say film speed is the manufacturer after testing according to ISO standards. None of us do that.
No safety factor, the reason I double the speed is because of the exposure scale of the paper, not to give me a "safety factor".
I thought that is what I had said......
I can't see you actually printing the shadow up around Zone IV. IMO, simply changing the EI doesn't really change the Zone placement. The relationship between the tones don't change. They are simply pushed up the curve.
I know I have not been doing anything wrong, I have been doing it for years.
I am not sure what you are trying to accomplish, but if your tests tell you to rate Efk 25 at asa of 6, then stick with it. You are already 2 stops below what the manufacturer rates the film. What asa the manufacturer rates a film, is just a guide, a place to start.
Originally Posted by noseoil
If that is what works for you, your personal asa, then stick with it. Use it and go out into the field and just take pictures, have fun, create. Keep records of your exposures based on asa 6, zone placements, filters, development times. Print what you like as expressively as possible. Then learn from your records what worked and what didn't and then go shoot some more.
I have not done a film speed/developmenmt test in years. From what I have read Bruce Barnbaum doesn't do them at all. He just shoots and makes adjustments as needed.
Last edited by RAP; 01-31-2005 at 05:55 PM. Click to view previous post history.
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