Paper ISO and exposure times

mrtoml · Nov 1, 2007

I recently made some prints on Ilford MG RC paper and made detailed notes so that I could replicate the results (ie exposure times, dodge and burn notes, and enlarger head height etc.). I also wanted to try to bleach and redevelop in Lith, but as my inexperience shows, this paper does not lith in this way at all well and the results are nothing like what I was getting on the RC WT paper from my last darkroom session.

I note that the booklet that comes with the paper states speeds for various types of MG paper and the speed for RC WT is P125 versus P200 for the normal paper. (Not sure what the P stands for BTW - paper?)

Does this mean that I can use my exposure notes for the MG RC and just readjust the times for MG RC WT keeping everything else constant or is there more to it than this? This sounds too good to be true :rolleyes:

Ray Heath · Nov 1, 2007

g'day mr

i'm not sure but then i don't look at things too technically, i'm more hands on

my experience with keeping notes is that initially it's a good idea as it makes you think about each part of the process, however i've come to see to see that each printing session is a different creative experience, you learn, you grow, your expectations change, to print each neg the same way each time is creativily restrictive

Ray

bdial · Nov 1, 2007

The simple answer is yes, you can use your MG RC notes and adjust the time for the WT. Note that the speed changes according to the filtration, so you need to look at the speed numbers for the filtration you'll be using.
The calculated exposure probably will not be exact, but you should be close.

Ray Heath · Nov 1, 2007

g'day bdial

why would the calculated exposure not be exact?

mrtoml · Nov 1, 2007

Ray Heath said:
g'day mr

your expectations change, to print each neg the same way each time is creativily restrictive

Ray

I guess you have a valid point here, but I am merely trying to correct a mistake I made last time. I just want to print the same images again in a similar way on a different paper for a toning experiment. I don't want in this particular case to have to start all over again unless it is absolutely necessary.

Although if I revisit the negatives again later I may well change the way I print them (more experience or a different mood and so on will suggest potential changes I guess).

mrtoml · Nov 1, 2007

Ray Heath said:
g'day bdial

why would the calculated exposure not be exact?

I think my worry is that from what I have read the speed of papers is standardised on producing a mid-grey tone. So if normal RC and WT RC multigrade produce maximum black say at slightly different times to each other (all other things being equal) then the time for one paper based on mid-grey will be off for the other paper. I am guessing here and have no idea whether this is true or not.

bdial · Nov 1, 2007

The time for mid-grey will be different, but proportional to the speeds.

The reason it won't be exact is that the character of the papers is different, and a numerically equivalent exposure may not be what looks best with the new paper.

Ray Heath · Nov 1, 2007

bdial said:
... The reason it won't be exact is that the character of the papers is different, and a numerically equivalent exposure may not be what looks best with the new paper.

which is exactly my reasoning for not trying to do repeat the 'same' print

what you will want to repeat is any burning and dodging, think of those timings as stops

e.g
the background needs twice as much exposure as the foreground, so base expose plus base exposure again while dodging the rest of the print = +1 stop;

the subject needs to be lightened slightly, so during the base exposure dodge with a shader for half the time = -1/2 stop

so, all you have to do is establish a new base exposure and contrast level, that shouldn't take more than 1 or 2 test strips as you already know how the major tones can look

Ray

mrtoml · Nov 2, 2007

Thanks. That's all very helpful.

Paper ISO and exposure times

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