Is B&W Print Contrast Affected By....greenspun.com : LUSENET : Large format photography : One Thread
exposure duration under the enlarger (ie, reciprocity effects), time in paper developer, or agitation in devoloper? Thanks. Andre
-- Andre Noble (email@example.com), October 10, 2001
All of the things you mention can have an effect... why don't you describe your experience with particular working methods & give everyone a better sense of what may be troubling you.
-- ernie gec (firstname.lastname@example.org), October 11, 2001.
Well,I'm about 5 years into occaisional, but fairly regular black and white printing in my home darkroom with an Omega ProLab condenser enlarger. To this day, I still have problems with excessive print contrast (blocked up higlights, printing with #1's and #2's, excessive burning-in required, etc.,) I upgraded my enlarger to diffusion with flashed opal glass, and this helped alot, but recently while printing some cibachromes, I discovered this conversion left a noticeable central hot spot. Hence I feel I have to return to the condensers. At least this way, the light is more even across the print. I know the callier effect will not effect color reversal printing, so returning to a condenser enlarger will be a boon to cibachrome printing in terms of reduced exposure times.
Anyway, back to black and white issue. I've seen some master printer's work, and description of their techniques in Photo Techniques magazine, etc, and can compare their print tonal range, their dodging and burning efforts, etc. I'm struggling too much with print contrast.
Therefore I'm trying to tweak my overall technique to improve the ease with which I can make a good print. For example, I recently began to develop negatives much more carefully now to control for contrast range. FWIW, it seems the negatives which I do print nicely seem flat, nothing like the sample ideal negatives in the Kodak black and white reference guide, for example, or like a negative which intuitively looks properly developed.
Another possible tweak might be the following: I had sometimes long exposure times with the 75 watt bulb in condenser house, but am now set up for much shorter exposures with a 250 watt. I hope will improve contrast control to a small degree because shoter times, means less reciprocity failure in the highlights, I reason. I have also incorporated use of black and white filters on the taking lens to help put some tone in otherwise white skies, etc., and finally, am in much better awareness of the importance of not over developing film.
Finally, I have continuously agitatedmy prints in the developer, and wonder if this is another potential source of increased print contrast? Andre
-- Andre Noble (email@example.com), October 11, 2001.
It is very important that you have the proper exposure when you make your negative. Deciding on the correct exposure for your negative is the most important factor in determining the success of your print. Underexposure will merge low values to black. Overexposure will block the high values.
You can determine which is the correct exposure for your film, developer and paper by trial and error. The more you do, the better the feel for your exposure. Since you will be experimenting, standardize as much as possible, film, developer, developer temperature, paper and paper developer.
Consistency in exposure and processing is the key to getting a good product out of your darkroom. Good luck.
-- Joe Lipka (JoeLipka@cs.com), October 11, 2001.
If you never calibrate you will have contrast problems for the rest of your days! Get a copy of "The New Zone System Manual" by Minor White, Richard Zakia et al. and get to work. It seems to me (just guessing from your post) that your negs are overdeveloped (hence the need for a 250W bulb!) and overdeveloped (blocked highlights and too much contrast). You need to determine first your film speed: i.e. the minimum exposure needed to get adequate shadow detail (we zonies calibrate to Zone I or Zone III) and then find the development time to give you printable whites. You can do all this without a densitometer quite accurately. Most books recommend measuring film- base+fog denisty, the Zone I and the Zone VIII density with a densitometer. However, the book I recommended details a method of calibrating wihtout a densitometer. I don't know where you are in the world, so, if that book isn't available, drop me a line off-post and I'll send you what I have on the subject if you are interested. Regards,
By the way, all the things you mention do make contrast differences in B&W printing, but miniscule differences compared to proper exposure and development of the neg. If you are having such consistant problems, this is where you have to look for a solution.
-- Doremus Scudder (ScudderLandreth@compuserve.com), October 11, 2001.
Paper contrast is not affected by its exposure time to any noticeable degree, nor does paper suffer from reciprocity affects at any reasonable exposure time. The developer temperature has a big effect on contrast, and the time and agitation have a much smaller one.
You should aim to develop B&W paper to finality in any case. That is, you shouldn't have to snatch the paper out of the developer at a very precise time, otherwise you'll never get a full rich black in the print.
Perhaps you should look into using a compensating technique for your B&W negative development, or adjusting the exposure of your negatives to give more shadow detail.
-- Pete Andrews (firstname.lastname@example.org), October 11, 2001.
Andre Noble wrote: "it seems the negatives which I do print nicely seem flat, nothing like the sample ideal negatives in the Kodak black and white reference guide, for example, or like a negative which intuitively looks properly developed".
Andre, I think this is the problem. You seem to had habit to overdevelop the negative, hence your negatives had too much contrast. My negatives are thin and I could say thay are "flat" if I didn't know that this "flatness" is exactly what I need for good printing. Manufacturer's suggestions about speed and development time usually assume the desired contrast is ca. 0.62. I've found this is almost never good for me; I prefer 0.5 or even less (even though it depends on the subject brightness range and desired local contrast). When I start the new film (or developer) my starting point is decreasing ISO speed twice (1 stop less) and reducing the recommended development time 50% (with T-grain films slightly less: 20-30%). Occasionally I develop negatives to CI 0.6-0.8 if they are targeted to paper #0 and #00. Again, it depends on the scene.
I don't think the points you have enumerated in your initial question have any essential effect in the contrast; their effect is subtle and can be used in fine tuning only.
-- Andrey Vorobyov (AndreyVorobyov@yahoo.com), October 11, 2001.
Hi Andre, I'll open a bag of worms. Light source. I installed a Zone VI cold light with Compensating developing timer on the old DII and my experience has been just the opposite of yours. I keep trying to find ways to get more contrast into the negs. The negs with this light seem to need a very long scale to fall onto a number 2 paper. Of course with that long scale comes more local contrast which I think is a good thing. This has all been discussed before a million times I suppose.
-- Jim Galli (email@example.com), October 11, 2001.
To convince yourself that your negatives are the problem, buy a step tablet and practice printing from that. If you are still having problems printing the easily calculable contrast ranges from that, then you have a problem independent of your negatives. I found Anchell's description in "The Variable Contrast Printing Manual" remarkably easy to follow. As others said, the guess is that you will be able to print from the step tablet exactly the contrasts you want and you will need to look more carefully at negative development. Even so, you'll learn a lot about how to print by using a step tablet (I recommend getting 1/3 stop intervals, by the way as I found my 1/2 stop tablet too coarse).
-- Eric Pederson (firstname.lastname@example.org), October 11, 2001.
"If you never calibrate you will have contrast problems for the rest of your days!"
There's no substitute for having a properly exposed and developed negative.
-- neil poulsen (email@example.com), October 12, 2001.
The type of light source you use (condenser or diffusion) definitely has an effect on contrast. That's why when you're doing zone system testing you aim for different negative densities depending on which type enlarger head you use. However, once you get your negative exposures right through proper testing, it shouldn't matter which kind of light source you use. Both will provide basically identical contrast with negatives that have been properly exposed and developed for the particular type of light source that you use. If someone has done film speed and development testing while using a diffusion light source, and then switches to a condenser but keeps film speed and development times the same, the resulting negatives will tend to print with greater contrast than he or she was used to. And vice versa with a switch from a condenser head to a diffusion head - the resulting negatives will tend to print with less contrast. Once the optimum time in the developer is reached, additional time doesn't seem to have much effect with today's materials, though Bruce Barnbaum uses an unusually long development time (4 minutes I think), in the belief that it gives him richer blacks. I've tried times up to 4 minutes without noticing any significant difference from my normal time of a minute and a half with Ilford Universal developer and Kodak Polycontrast Fine Art paper. Agitation is important mainly to insure even development and a consistent agitation method is important to help achieve consistency from one print to another. I doubt that it has a significant effect on paper contrast (unlike film) though I've never tried using different agitation methods and observed the results.
-- Brian Ellis (firstname.lastname@example.org), October 12, 2001.