Does anyone else need dense negs for cold lights?

[erik_asgeirsson]

I just switched to a cold light head, and I'm finding that my

negatives print better if they are substantially denser than what

worked well with my condenser. I used to shoot FP4+ at an EI of

about 100, but it looks like an EI of 64 would be a better match for

my cold light. Has anyone else noticed this, or is it most likely

something with my system?

[michael_briggs2]

Comparing a condenser and diffuse-light (such as cold light) enlarger, to obtain prints on the same paper grade, you should need higher negative contrast for the diffuse light source. It is the contrast more than the EI that should need changing. Obtaining higher contrast by increased developing should either leave your EI the same or slightly higher.

 

Perhaps you are obtaining higher contrast with a reduced EI: with some films that would move the exposure onto a higher contrast portion of the film's characteristic curve. However, you change in EI seems too small for this explanation.

 

You might want to try modestly increased development time and see if that gives better results with your new cold light head.

[armin_seeholzer]

Hi Erik

 

Michael has the right point. You should work to a CI up to at least 0.75 for condenser you work with arround CI 0.58.

On mine I have to go even a bit higher but 0.75 is a good starting point. Thad means about 1-2 minute longer devl. depends on film and developper.

Good darkness!

[sal_santamaura]

Erik said denser, not higher contrast. Erik, are you making denser negatives simply because printing times are shorter? That would be consistent with the typical cold light head's output being more actinic than that from a condensor. If you can't shorten printing times, and don't want to stop down your enlarging lens for fear of diffraction, either get a Metrolux or Zone VI controller/timer (which will enable decreasing the head's output) or simply screw some neutral density filtration on your lens. The latter approach will be less expensive but make focusing somewhat more difficult. I suggest starting with a 1-stop ND.

[hal_hardy]

I give 50% more development with no exposure adjustment.

[erik_asgeirsson]

Sal,

<p>While the longer exposure time with the denser negative is nice, my issue is more of a contrast related one than anything else. On my last shoot, I exposed everything as I did before the switch to a cold light using my spot meter, placing the shadows on zone III as usual, except for one negative, where I accidentally placed the shadows on zone V. It still had a five stop range between shadows and highlights (as did most of the "normally" exposed negatives). Everything was developed in d-76 1:1 for 11 minutes (FP4+). The only negative that wasn't horribly flat on Seagull grade II was the one that I accidentally overexposed. It also had a richer feel, more detail, and good highlights and shadows, yet the development was the same as for all the rest. I still have two undeveloped backup exposures for some of the negatives that printed flat, so I'm going to try developing them longer, say for 15 or 16 minutes, to see if they are salvageable.

[sal_santamaura]

OK Erik, now that you've defined the situation more clearly:

 

First, your negative that received more exposure seems to have moved low values up off the toe, thereby providing more shadow detail. This benefit should be visible when printing it with your old condensor head too.

 

Secondly, if, as you say, the remaining "normally" exposed negatives have an identical five stop range, but don't result in the same "good highlights," I'm somewhat at a loss to explain. I don't use FP-4+, but Ilford's technical data sheet for it shows a small glitch in the mid-density region of the characteristic curve. Perhaps you've moved that anomoly to a point where it helps your situation.

 

Finally, have you always printed on New Seagull G? If you switched over from some other paper at the same time as changing heads, note that Seagull, especially grade 2, has an enormous toe, nearly as pronounced as seen with Azo in Dektol. It's *very* difficult to make white with that paper. One fine printer I know uses only Seagull grade 4, flashing as necessary to retain detail.

 

Diffusion heads certainly require negatives with greater density range than do condensor heads, comparing the same paper grade/filter in each case. Your description, however, makes it difficult to blame this characteristic for the problem.

[chris_jordan__boston_1]

If you develop your negative too much longer, you can run the risk of compressing your highlights and losing some of the more subtle tonal qualities in this range. You mentioned printing on a grade II. You can print on a 3, 3 1/2 or 4 (or some combination) with the thinner negative, and obtain wonderful results, with the further advantage that the negative can be printed with either head in the future.

 

-Chris Jordan (Boston)

www.jordanphoto.com