paper speedsgreenspun.com : LUSENET : Large format photography : One Thread
To my surprise the archives seem to have nothing on the subject of speeds of paper (contact or enlarging), nor do I find anything in my manuals or paper manufacturers' spec sheets. My problem is a simple one: when I've determined the correct exposure for a given negative on a specific paper, how can I calculate with precision the correct exposure for another paper or papers. I realize that I could run my own tests (and to an extent I've already done so much in a hit-and-miss way), but this seems to be an area (as with the much-discussed matter of speeds of films) where pooling of experience might be of general benefit to many on the forum. My questions:
(1) Nomenclature. Take, for example, Oriental Seagull fb dw glossy G-3: ISO speed P400, ISO range R80. To what do "P" and "R" refer? What is the range?
(2) Relative speeds. The same paper as above in the very hard contrast G-4 grade is ISO speed P200, ISO range R60. How are the G-3 and G-4 numbers related to each other in terms of exposure?
(3) Are paper speeds consistent from paper to paper and from manufacturer to manufacturer? Are all P200 papers equally sensitive?
(4) Are sharpness or other image qualities, all else being equal, related significantly to paper speed? Contrast is not an issue here for the purpose of this question.
Thanks in advance for any replies. Good light, Nick.
-- Nick Jones (email@example.com), October 10, 2001
The P is the Paper Speed and R is the Range Number. Paper speed is pretty much self explanatory, but I have found that it's not quite as exact as film speed. A paper rated P400 should be twice as fast (one stop faster) than a P200 paper. The Range number refers to the paper's contrast range. The higher the R number the wider the contrast range. There are ISO standards for these and manufacturers should and most like do, conform to them.
There is no standard that I'm aware of that relates paper speed with paper grade; that's something totally dependent on the emulsion characteristics of the specific paper. Paper speeds are not consistent from manufacturer to manufacturer for a given grade, but the P numbers should be. All P200 speeds should respond equally to the same exposure. In practice you may not find this to be true and I believe it's because the spectral output of enlarging sources differ from the spectral response of the paper.
I do not believe sharpness is specifically related to paper speed.
There's some good information on paper speed and range numbers in Steve Anchell's Variable Contrast Printing Manual and a good article ran in Photo Techniques about a year ago.
-- Pete Caluori (firstname.lastname@example.org), October 10, 2001.
Printing by numbers, whether B&W or colour, will give you results no better than a minilab machine print.
No good printer I've ever known 'does it by the numbers', so you may as well just ignore anything that's printed on, or in, the box except for the make, type and grade.
There's no short-cut to printing expertise, I'm afraid. Just find a paper you like, or one that has a good reputation with experienced printers, and stick with it. Even then, you'll have to waste a sheet or two checking the speed, every time you get a new box or batch number.
-- Pete Andrews (email@example.com), October 11, 2001.
Nick: Listen to Pete. He gave good advice. I never even look at paper speed numbers. What is more important is picking one or two papers and becoming familiar with them. Then you need to standardize your processing so that you can repeat results. I make notes on prints that I will print more than once, but even then I have to test each time. If you become familiar with your paper, the test can be very quickly done. I have noticed that paper can vary almost a stop from batch to batch, due to age, storage, etc. It is important to use a timer for your deveopment so that you give each print the same time. Don't pull a print out of the developer when it comes up too fast. Toss it. The most important piece of equipment in a darkroom is a large trash can. If you get familiar with a particular paper, you will be able to "eyeball" the projected image enough to get in the ballpark for your tests.
-- Doug Paramore (firstname.lastname@example.org), October 11, 2001.
Thanks, Pete Caluori, for your thoughtful and precise responses to my questions about paper speeds. Now that I know to what the manufacturer's data refer to, how P numbers are related, that nominal paper speeds are less consistent than film speeds esp. between different manufacturers, and that sharpness is not (as the case of film might suggest) related significantly to paper speed, I think I can improve my printing.
I begin by making test prints of all negatives on Polycontrast III RC, always initially at the same exposure, then perhaps one or two additional sheets to establish an approximately correct exposure. The trick then is to move on to any one of a half dozen or more fiber papers that I select from according to subject (landscape, still life, portrait, etc.) in relation to surface, contrast, stock and image tint, and response to toners. The P number may not be as exact as film speed, but it seems to me the only rational starting point (my papers range from P200 to 640), and, if the number does prove inaccurate (because the result does not correspond to what the P number of the test print would indicate), at least I can come to some definite conclusions about the accuracy of the particular paper's or manufacturer's data.
It seems to me that the greater number of paper options I have, the greater my photographic palette and potential for expressing my interpretation of the subject. I agree with Pete that photographic printing is not merely a matter of numbers, but all we're dealing with here is predicting the response of a given paper at a given exposure precisely in order to enhance one's artistic options and flexibility. Simply put, Doug, I could never get by with your one or two papers.
I'm still amazed that the standard introductions to LF photography do not take up the question of paper speed. Manufacturers' ISO film speeds are notoriously inaccurate (usually too fast), so we have our exposure indexes, either worked out independently or suggested by experts (for example, Steve Simmons, Using the View Camera, pp. 73- 74). Why can't we have similar working numbers and tables for our papers? Nick.
-- Nick Jones (email@example.com), October 12, 2001.