Hope, a fading glowThe hotter temperatures make plants become net emitters of carbon dioxide instead of net absorbers of it. It seems that as temperatures get hotter plants risk losing water through evaporation and respiration. In order to prevent water loss they reduce the size of their pores, and that in turn reduces the amount of carbon dioxide that the plants may take up.
LESSON LEARNED HERE: If you underexpose print films, you will not get the necessary shadow details. But given the wide latitude of print films, you can overexpose print films by 2 stops and yet get great results.
This ability for color neg films to be over-exposed and still reproduce decent images also accounts for the ability of print films to record much more brightness range than slides.
We often refer to this as “dynamic range”. In a slide, highlight information is stored as clear parts of the film that at a point contains nothing more than blank film base. Color negs continue to stack up increasing density (highlight) information until the film simply can’t record any more information.
Overexposing color negative film also makes it easier for most labs to get decent prints or scans, because more info is recorded. How much exposure compensation is needed? This probably varies with film but start with +.3 to+.5. Some film, maybe even one full stop.
This latitude doesn’t mean you’ll get an optimal result. It just means that within these ranges you can get a useable (depending on your purpose) result. Over- and under- exposure are mistakes. Film latitude should not be relied upon to cover mistakes in exposure.
Many people will intentionally reduce exposure of slide film by between a 1/2 stop and a full stop to increase colour saturation, retain detail in highlight areas and reduce grain. Some will also intentionally increase exposure on negative film by 1 to 1 1/2 stops to increase colour saturation and preserve details in shadow areas as well as reduce grain (grain can become very noticeable in underexposed areas of print film).