Excessive contrast

Owned by reading the negative as evidence. Part XIII owns the measurement of contrast and this entry owns the fault.

What you see

Shadows that look right and highlights you cannot see through. On a light box the sky, the white wall or the bright window is a solid black area on the negative with no detail in it. Printed on the grade that suits your other negatives, the print has empty white highlights and blocked shadows at the same time, and going softer rescues one end while losing the other.

The distinguishing feature is that the shadows are not the problem. If the shadows are empty too, this is a different entry: see empty shadows and thin negative.

Likely causes

1. Over-development: too long, too warm, too concentrated, or agitated too much.
2. A long subject range — a high-contrast scene rendered faithfully. Not a fault.
3. Underexposure at normal development, which lands the shadows on the toe and leaves the highlights on the straight line, so the negative reads as contrasty while being thin.
4. A development time established for a different agitation scheme, which is the commonest hidden cause.

What is happening: the chemistry and physics

Development builds density fastest where the most latent image is, so extending it separates the highlights from the shadows faster than it raises either. That is the whole of contrast control on film, and every one of the four levers reaches it.

Time. More time, more gradient, up to the point where the highlights exhaust their local developer.

Temperature. ILFORD’s own compensation chart turns an 8-minute development at 20 °C into 7:15 at 21 °C and 6:30 at 22 °C — from which this course takes the working figure of about 9 per cent of the development time per degree Celsius near 20 °C. Two degrees warm is close to a fifth more development. Kodak’s Z-133 is stricter still for a laboratory: variations greater than ±0.3 °C in the developer affect process control and image quality.

Concentration. A more concentrated bath develops faster and resists local exhaustion, so it carries the highlights further.

Agitation. Faster resupply means faster development where consumption is highest, which is the highlights. ILFORD ask for spiral-tank times to be reduced by up to 15 per cent for continuous agitation, which is the size of the effect stated by the maker.

!Contrast index is a specification of four numbers, not one

A published development time is the time that gives the intended gradient under the agitation, at the temperature and at the dilution published beside it. Change any one of the four and the time is no longer the right time.

That is why “I developed for the recommended time” is not a defence: the recommendation was for a whole condition, and most excessive-contrast faults are one of the other three numbers having quietly moved.

Diagnostic questions

1. Where are the shadows? Well above the rebate with detail in them: the exposure was right and this is development. At or below the rebate: it is underexposure and the entry you want is thin negative.
2. What was the actual temperature? Measured with a thermometer you have checked against a second one.
3. What was the agitation scheme, in inversions and intervals? And is it the one the time was established with?
4. What dilution, and which of the maker’s two times for it? ILFORD publish 7½ minutes for HP5 Plus in ID-11 stock at EI 400 and 14 minutes at EI 1600; those are the same film and the same bath.
5. Was the subject itself extreme? A sunlit street with deep shade has a longer range than the process was designed to hold, and rendering it faithfully produces this negative correctly.
6. Every frame on the roll? Yes points at the process. Only the outdoor frames points at the subject.

Corrective action

Print it softer, which is a real answer and costs nothing. A grade 0 or 1 print with a little burning-in handles a great deal.

Chemical reduction is the wrong tool here and the geometry says why: a cutting reducer removes an equal quantity of silver everywhere, so it removes a larger proportion from the thin end and raises contrast further. Kodak’s own header calls the ferricyanide-thiosulfate bath a cutting reducer for correcting over-exposure and clearing shadows — a different job. The proportional and flattening reducers that would lower contrast are not taught in this course.

Prevention

Reduce the development time and re-establish it as a measurement, not as a guess: the development-time series finds the time that gives the contrast index your enlarger and paper want.

Write the whole specification down — film, dilution, time, temperature, agitation scheme — because four numbers changed independently is what produced this.

And where the subject was the cause, expose for the shadows and cut development, which is the classic answer and is a decision rather than a repair.