Willie Jan said:with the -3, +3 test you mean why bother about the zone i, because it will not show up on your print eventually...
No, zone I will show up in a fine print, but it is impossible to determine by printing test negatives, using the basic exposure time for the paper, as the classic zone system description does.
So test about the two possible edges of the paper (6 stops).
Yes, and test for something that comes out in visible and meaningful differences and not number that can only be read on a densitometer.
Why is half the world than telling to get zone I right ????
is that some old film solution, no longer usable for new film types?
Zone I is probably a leftover from the ASA(now ISO) film standard. It is, as an industrial standard, very useful to prevent the manufactureres from claiming unrealistic high film speeds, but beside that it is of little practical value.
Willie Jan
BBarlow690 said:No densitometer required, and you work with Zone I (the low end of your materials - tuning the basses of the orchestra) and Zone VIII (the high end - tuning the piccolos). If you get both ends right, the middle takes care of itself. If you try to tune the violas, the ends can still be flat or sharp. This way matches the materials to each other, making full use of each.
Bruce Barlow
www.circleofthesunproductions.com
Willie Jan said:would it than be a better test to shoot a gray card with a kodak step wedge, develop, find the time where the gray is 0.70, and make a print of it so that the print is exactly 0.70 at gradation II. When so the kodak curve should be from white to deep black.
Conclusions after print is made:
If the white is not white, the density of the neg is not high enough (longer development)
If the white is to white over more steps, the density of the neg is to high, (shorten the development)
if the black is not black, the density of the neg is not low enough (higher EI).
if the black is to black over more steps, the density of the neg is to low (lowe EI)
Donald Miller said:That criteria is not .10 over B+F as the film speed determinerDear Don,
Um...
Yes it is. At least for ISO speeds (based on post-1959 ASA). This is the left-hand speed point and the right-hand speed point is 1.3 log exposure units to the right; this second speed point must give a log density exposure of 0.8, correspomding to a gamma of approximately 0.615.
The ISO speed is the exposure E at the speed point (0.10 above fb/f), in lux-seconds, divided into 0.8.
What other figure had you in mind? I can only imagine that I have misunderstood you.
Of course, ISO and the Zone System are not necessarily congruent, and you are absolutely right that Zone V is mentioned nowhere in ISO standards; nor is any of the Zone System.
Cheers,
Roger
L Gebhardt said:First get your development down. Film speed is dependant on development.
Roger Hicks said:But because of the choice of speed point of 0,10 and gamma of approximately 0,62, the variation is surprisingly less than might be expected.
Cheers,
Roger
Daniel_OB said:What one should to do if density in zone I (or II....) is 0.1 and at the next zone (say zone II) is 0.11????? Hex, this is a pitfall with zone system and iso too.
What is for photography important is not just density but the SLOPE of the curve too. How to set the standard for both? That is the ?.
www.LEICA-R.com
Willie Jan said:i measured the density of a kodak gray step card i made a photo of after printing.
The (white) was 0,14 (should have been 0,04 = agfa mcp310 paper)
The M (zone V) was 0,7 (is fine)
The B was 1.70 (=number 16) should be 1.6
So this also showed my curve as a circel which was ok at zone V.
What to do next to get this fixed?
Because the white was not white enough should i develop longer to ge a higher density, or agitate more?
noseoil said:Willie, longer development or increased agitation will have the effect of raising contrast. Without a densitometer, I'm not sure how the shape of the curve can be affected by changing the method of increasing contrast. More tests! tim
P.S. You really must get a 4x5 camera and some sheet film soon, you are heading into danger with these tests!
Roger Hicks said:Donald Miller said:That criteria is not .10 over B+F as the film speed determinerDear Don,
Um...
Yes it is. At least for ISO speeds (based on post-1959 ASA). This is the left-hand speed point and the right-hand speed point is 1.3 log exposure units to the right; this second speed point must give a log density exposure of 0.8, correspomding to a gamma of approximately 0.615.
The ISO speed is the exposure E at the speed point (0.10 above fb/f), in lux-seconds, divided into 0.8.
What other figure had you in mind? I can only imagine that I have misunderstood you.
Of course, ISO and the Zone System are not necessarily congruent, and you are absolutely right that Zone V is mentioned nowhere in ISO standards; nor is any of the Zone System.
Cheers,
Roger
Roger,
With all due respect, I beg to differ with you. I have taken the liberty of copying and pasting an earlier post by Stephen Benskin, who has done a great deal of study on this matter. Perhaps this will explain what I am addressing.
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Quote:
Originally Posted by ElectricLadyland
basically i dont see why having the EI precisely what it is matters or is beneficial, becasue curves vary between films so even same EI films will have differnt tones for the same exposure... but i thik what is important is knowing that at any given EI for a particualr film, this meter reading and developer/time will develop to this tone. what are some thoughts on this?
Quote: Stephen Benskin
Excellent observation. The fixed density method of the ISO standard is really a short cut, and the Zone System fixed density method is conceptually flawed. Most people just want to know just enough to make something work. They usually aren't interested in the reason why.
Without going into great detail, the most accurate speed method is based on the gradient of the curve and not a specific density. It's call the Fractional Gradient Method. Todays ISO standard is representative of this method except it uses a fix density short cut method. Lyod A. Jones determined, after extensive testing, that consistently high quality negatives are produced when the speed point is at a point on the curve where the gradient is 0.3x the average overall film gradient. In many cases, this isn't at 0.10 over fb+f.
With this in mind, using any fixed exposure or density method of print determination is also counter indicated since there isn't a specific base density in the negative to key on.
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