Developing Times Question

<p>How does the amount of time when developing film effect it? For instance, on Kodak Tri-X 400 the time for developer is 5.5 minutes at 68 degrees. What would happen if you only left it in for say 4 minutes, or extended it to 8 or 9 minutes?</p>

<p>The time of immersion is a factor of the ingredients of the developer, the dilution of the developer, and the film composition. Published data provides the time change valuables of temperature and dilution.</p>

<p>These values are not engraved in stone and can be altered based on need. As an example, you might choose to over-develop to gain ISO sensitive or conversely under-develop to lower ISO. This is called pushing or pulling.</p>

<p>The greatest impact of time changes will be a contrast change. As a rule, the longer the development time the greater the image contrast. This is because the image consists of silver salts that have experienced different levels of exposure. As development time lengthens, the highlights (areas receiving plenty of exposure) continue to blacken while the shadows (areas receiving minimal exposure) gain density more slowly. The net effect is a broaden difference highlight to shadow. Extended development also results in increased grain.</p>

<p>Everything seems to have pluses and minuses. The magic of the developer is that it is selective, meaning it has the ability to differentiate between exposed and unexposed silver salts. If development grossly extended, the developer will lose its ability to make the make this distinction. What now happen is shadows areas receiving little or no exposure, now begin to develop thus the film gains density in the shadow areas. This does not happen in the highlights because they are already near or at maximum black. The result of super elongated development is a drop in contrast.</p>

<p>See page 11 of <a href="http://www.kodak.com/global/en/professional/support/techPubs/f4017/f4017.pdf">F-4017 Tri-X Data Sheet</a>. The different curves on each graph are different development times.<br>

Note that it does NOT just slide the curve to the left as you increase developing time. (If it did, then it would be truly increasing film speed.) It just increases the contrast.<br>

On those curves, the horizontal axis is exposure, the vertical is density of the film. Both scales are logarithmic. 0.3 units is one stop (twice the exposure, twice the density).</p>

<p>Time, temperature, and Ph all affect density and contrast. Based on your question, you would lose at least 2 f stops of speed and 2 contrast grades not to mention that you would have virtually no shadow detail.</p>

<p>Lynn</p>

<p>When film is properly exposed you will get a good black level when printing. Longer development times add more density to the highlights. The goal is to obtain highlight densities that will result in good white, or highlight values in the print and good black print values. If you under-develop you will lower the highlight values and it will be difficult to obtain good whites in the print. In this case, it would be wise to use higher contrast paper. If you over-develop then it will be easy to get highlights that are "blown out" with little or no detail in the print. You can increase exposure in the enlarger to tone down the pure white values so you show some detail but that usually will yield black values with little or no texture detail. The goal is to get rich dark values with detail and highlight values that show detail, with little or no print values that are pure white (no detail). Getting a correct development time is important. </p>

<p>Less development time = less contrast, lighter highlights<br>

More development time = more constrast, darker highlights, more grain<br>

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