Overexposing C-41 for more saturation rule
Can someome please post comparison examples of this to actually 'prove' it?
From my own past results, and seeing those of a user test on Ektar in the Ektar thread show that underexpose gives more contrast and more saturation or perceived saturation.
While overexposing flattens out the contrasts and the colours seem more muted.
I have never noticed that I get more saturation when slightly over exposing C41 film. In fact it tends to reduce contrast in the shadows, and that seems to give less saturation in the shadows.
It's like this.
You really get more exposure in the shadows, and the impression that this will dilute them is right. But with optical printing, a (slightly) denser negative will require longer printing. Longer printing means more exposure in the shadows, and this puts them back in track.
Scanners behave differently. Usually, the software used to process the image will account both highlights and shadows before a positive picture is produced.
A dense negative will require lengthier printing, optically. Lengthy exposures causes more halide to be affected. When more halide is developed, more dye is produced. Lengthy printing with a normally exposed negative (with less density) will cause the hues to go dark. But when the dyes in the negative are already dense to begin with- something achieved with overexposure in colour negative stocks- the light blocking power of the dyes prevent details from darkening. The dyes aren't quite opaque enough to totally curtail exposure.
In the past when we used low grade or "budget" colour negatives (we had low end Kodak colour film which was very pastel, or the earlier Luckycolor films), the only way to give punch to their normally washed out rendering was to slightly overexpose them. The Kodak had a box speed of 100, but it gave nice results at EI 64. Luckycolor and Eracolor (both from China, and this was in the early 1990s) were supposed to be 100, but EI 50 or even EI32 did better. In fact, the "budget" Kodak 100 was eventually repackaged as KodakSP 64.
These poor grade negative stocks produced low dye densities with normal exposure. The only practical way to make them produce more dyes for more punchy hues was to increase exposure- more exposure, more development, equals more dyes.
Here are two examples of "over-exposed" Ektar 100:
In both cases, I rated the film at 64 instead of the 100 box speed.
And if you look at my scans from a recent trip to Spain, all were taken with C41 film rated slower than box speed: http://www.flickr.com/photos/4326913...7623677351197/
Now, I pretty much only use Ektar 100, rated at 64, for color.
There may be somebody that has examples but (!) the comparison is always tainted by the choices made by the person responsible for printing them.
IMO, to get a meaningful comparison, you need to try it yourself in your system.
Mark Barendt, Beaverton, OR
"We do not see things the way they are. We see things the way we are." Anaïs Nin
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Well in scanning I usually scan my my negs as positive, and set the levels for each channels individually, invert then do any colour correction (if needed at that point, usually not).
markbarendt: I wont be optically printing for a long time yet, so it would be nice to see the results and conclusions of others.
It has always seemed counter intuitive to me, especially considering that it's common to *under*expose slide film for more saturation.
I would like to hear some opinions, but would actually prefer to hear some sort of logical theory that could explain these two suggestions. In the meantime, I'll drink some coffee and work on the whole "logic" thing.....
I hope this kicks in the logic thing...
Originally Posted by holmburgers
Colour slides are processed by reversal. So when chrome film is underexposed, less halide is developed during the first BW development stage, and leaves more undeveloped halide in the emulsion for the colour development after reversal.
When more halide is left for reversal, more gets to develop. And when more silver develops, the coupling process produces more dyes. And what happens with more dye? More saturation.
Colour negatives aren't developed by reversal. So underexposing a colour negative emulsion will not yield the same effect as a film which goes through two development, and two exposure stages as it would in reversal (E6) processing
Underexposure will expose less halide- when less develops, less dyes form too. With less dyes, no saturated colours. Just muddy ones- grey from the lack of exposure, with little dye forming.
Overexposing (slightly) a colour negative stock OTOH makes more halide develop-able. More halide developing means more dyes.
A colour negative with punchy dyes will print with more punch on a positive material, when optically printed, that is.
Awesome, that makes perfect sense. Thanks!