how to judge/control contrast of a negative

I am trying to get my stand development times more accurately determined and seem to have the exposures where I want them. There is enough detail in the shadows for my liking.

At times, my negatives seem too thin so there is some underdevelopment as I seem to remember a recommendation that the contact sheet is the first and most important step in assessing your negatives.

I've followed the contact sheet directons in the Kodak darkroom book (10 seconds at f5.6) and the contact sheets I think turn out well are easier to print. The thin negatives, of course, print out very dark.

The contrast in these underdeveloped negatives seem to be more than enough. The situation is difficult lighting, nighttime under the usual spotlights found in modern homes. I agitate only a minute before letting the tank stand so I don't think I could agitate less.

I would imagine more time in the tank would exacerbate the contrast but is there a way to get thicker negatives?

more exposure

Yep llike bdial said - let in more light to activate more silver.

Maybe your lightmeter is off, or your shutter speed is off, or your aperture doesn't open and close. Good once over of your camera and lightmeter could help.

ymc226 said:

I agitate only a minute before letting the tank stand so I don't think I could agitate less.

I would imagine more time in the tank would exacerbate the contrast but is there a way to get thicker negatives?

Click to expand...

Just found this this morning (there was a url link here which no longer exists)

Maybe it will help.

Go to one of the many books on the Zone system. Take the time to understand what they are talking about, then take the time to do most of what they say to do.

Good examples are:

Ansel Adams The Negative

John Schaefer Basic Techniques of Photography"

Fred Picker Zone VI Workshop

There's many more.

I found Fred Picker's book the easiest to understand and apply. Take it at least as far as "The Proper Proof". One good thing about the "Zone" system is that it works for your camera, your shutter, your meter, your film, your developer, your paper, and your enlarger.

I fought determining my own ASA film speeds for years and usually felt frustrated. I finally broke down and took the time. I'm beginning to understand what all the books are talking about and understanding better negatives.

If I read your your post correctly, you are getting good negatives--properly exposed and developed. Your problems show up under "difficult lighting" and at "nighttime." That tells me that your processing is pretty good. The problem lies with metering, possibly reciprocity issues with long exposures.

To test, I would make several exposures outside in daylight with an average scene--one not terribly contrasty and not too flat. Develop these and check shadow values (for exposure) and overall contrast (development). If you are satisfied with these negatives, you have your basic development time and procedure established.

The issue then becomes one of proper exposure. Did you calculate reciprocity failure for long exposures? Check your metering technique. For some reason, you are underexposing with your home lights.

Once you have a basic time and procedure for developing normal scenes, start to figure out your plus and minus development times.

Also, how did you arrive at the 10 seconds at f5.6 for making contact prints? The data guide is only a guide. You need to do a test in your darkroom with your materials. Have you done a minimum time for maximum black test? This will give you the proper time for your materials. Paper varies quite a bit. One brand of grade two paper may require 10 seconds, another brand may require 20. Do the test first to make sure your getting a good base line for contact printing.

With my contact prints, I am getting just enough deep black near the sprockets using Arista Edu.ultra RC, the cheapest RC in the world. My shadows have enough detail but the negatives seem too thin. I just printed on RC paper to see if they are printable. They are but may need more contrast. As such, I will increase development time to see if that will make the negatives thicker and easier to print (ie, at grade 2 instead of grade 3.

What is your film ?

What is your dilution ?

What is your Exposure Index ?

How do you agitate it ?

It may be an issue of terminology, but "thin" negs are usually due to inadequate exposure. Increased development affects the highlights mostly. Overall density and shadow density especially, derives from exposure.
More development will increase your highlight density, and result in increased contrast, but it won't make your thin negs thick, at least in the ways most of us define "thick" and "thin" for negs
Your eyes and the film are able to record more information at either end of the scale than paper can. You may well be able to see detail in shadow areas of your negatives that will disappear into blackness when you make a properly exposed print.

With the exposure you've used that makes the sprockets just barely dissapear, what does the rest of the image look like? If it's too dark you are under exposed, too light means you are over exposed. No detail in highlights means your development may be too long, if the highlights are too dark the processing might be too short.

OTH, there is nothing wrong with using grade 3 to get a good print.