Negative Development
As I learn my way around film photography and the darkroom I have been frustrated with difficult to print negatives. I think this revolves around having negatives with too much contrast. I have come to understand through reading and practice that a high contrast negative is not a good thing. That contrast should get introduced during the printing.
Contrast means many things but I think in this context it means the dark areas of the negative (highlights in the print) are very dense or black. The shadows (the light areas of the negative) are very clear. Of course the trouble with this is there is very little in between. I think of this in terms of information but also gain or slope of a curve. As I have posted elsewhere if one takes a high contrast negative one has a very steep gain curve. (Sorry I am an engineer by training so this is a bit mathematical.)
The graph below attempts to illustrate this. A high contrast image has a very steep light curve. That is a small change in light in put on the horizontal axis results in a large change in light transmitted to the paper. This can be thought of in terms of exposure where a small change in exposure time results in a lot more light on the paper. This makes it inherently hard to control the exposure as you may be faced with quarter stop or smaller steps to achieve a 'good' exposure. This is especially true where the high contrast filters are concerned. These filters introduce (mathematically they multiply) another steep curve making control more difficult.
Anyone familiar with split grade printing on variable contrast paper will be familiar with test strips for the #5 high contrast filter such as below. From 8" to 16" (1 stop) is a marked increase in contrast. If one wants to print with this filter alone you could see easily requiring 1/4 stop or lower resolution to get the print to look good.
On the other hand starting with a low contrast negative makes this easier. The graph below illustrates such a low contrast scenario and now large changes in exposure time on the horizontal axis results in small changes in the exposed image. This allows more control to be introduced.
Contrast means many things but I think in this context it means the dark areas of the negative (highlights in the print) are very dense or black. The shadows (the light areas of the negative) are very clear. Of course the trouble with this is there is very little in between. I think of this in terms of information but also gain or slope of a curve. As I have posted elsewhere if one takes a high contrast negative one has a very steep gain curve. (Sorry I am an engineer by training so this is a bit mathematical.)
The graph below attempts to illustrate this. A high contrast image has a very steep light curve. That is a small change in light in put on the horizontal axis results in a large change in light transmitted to the paper. This can be thought of in terms of exposure where a small change in exposure time results in a lot more light on the paper. This makes it inherently hard to control the exposure as you may be faced with quarter stop or smaller steps to achieve a 'good' exposure. This is especially true where the high contrast filters are concerned. These filters introduce (mathematically they multiply) another steep curve making control more difficult.
 |
| High contrast or steep curve |
 |
| Example #5 filter test strip |
 |
| Low contrast curve |
Towards this end I was re-reading a great blog on photography by Andrew Sanderson called Thewebdarkroom. He has a post on making better negatives. He asks the question 'Are Your Negatives Good Enough?'. My answer being no I read on. Andrew emphasizes if you have jet black in your negative you have over-developed it. More development is often used to push a film to a higher speed. As David Kachel points out in one of his monographs more development time really just adds more overall contrast. He wants you to optimize for good local contrast (sometimes called micro-contrast) which is different.
Now I follow the recommended development times for the film and developer I use. In my case I am using Ilford LC29 and typically with Ilford films like FP4+. I keep a thermometer in the cabinet with my developer and use that temperature to compensate the development time using the Massive Dev Chart App on my iPad. This has worked OK for me. Now Andrew suggests an experiment to use a roll of film and bracket exposures on a whole film strip. Cut the film into 3 pieces and develop one normally, one 20% over the nominal development time and the last one 20% under the nominal development time. Then make a contact print where the exposure time for the contact print is sufficient to allow for the clearest area of the film to show pure black. (this area is along the unexposed edge of the film.)
I made the contact print on Ilford MGIV RC variable contrast paper but chose to expose it with no filtration. This makes it about a grade 2 paper. (I think in retrospect this may be a mistake. The contact prints are probably too contrasty to express the full range of the negative well. I probably should have exposed the paper under a #00 filter.)
 |
| Test strip |
Close inspection (very close as this is 35mm film) made me think the best print was at the nominal camera exposure (f5.6) but with 20% less development. Actually what convinced me that 20% less development time was better was not the f5.6 exposure as this was not perceptibly different than the same exposure at nominal development time. Rather in looking at the f4.0, one stop over exposed image the highlights hold more detail in the brightest section where a fuller range of shadow results. It is clear the over development lost some shadow detail. The nominal recommended development was not far off however but less development seems to give me more latitude.. Now this was a low contrast scene being indoors under dim incandescent light so I would expect more benefit with shots taken outside under bright sun conditions.
I printed this negative as a split grade print to show the potential of the print and also at filter #00 to show the full range.
First the split grade print. Most of the detail in the kachina is present in the shadow while rendering the cabinet mostly black. Plenty of subtle detail in the highlights.
From now on I will develop at 20% less development time.
First the split grade print. Most of the detail in the kachina is present in the shadow while rendering the cabinet mostly black. Plenty of subtle detail in the highlights.
 |
| frame 3A #5 32 sec #00 45 sec f16 |
From now on I will develop at 20% less development time.
Comments