Hey Keith;
Over exposing color film helps with saturation, and without doing so you cannot get a convincing black from an RA-4 print.
But Chris! I routinely get exactly the results that I want, including convincing blacks, by exposing at box speed or a small (half stop or so) tick slower if I want more defined primary colours.
Moreover, I think it is in the film-makers' best interest to make it as easy as possible for people to get the best possible results with their product.
I suspect that the differences in people's ratings of c41 films comes down to personal preferences about the role of the primary colours and their metering practices. I do not deny that you (Chris) get better results for your taste, using your methods. And that is how it should be- everybody should experiment and find their own way. For my taste, rating fuji 160 at 100 or so gives me a rather pronounced shift to primary colours. Frankly, I do it when I want velvia-esque rendition with strong primaries but I am worried about exposure latitude.
But still... I am always mystified why some propose rating a modern c41 colour film a full stop slower and simultaneously imply that this is the way to get the best result. Best for what? The
only c41 films of which I am aware that really always need overexposure, in my own experience, are the b&w chromogenics- the Kodak bw400CN and xp2. Especially xp2 looks downright flat to my eye if rated at box speed. I'm not sure what's up with that box speed, Mr. Ilford!
Anyway, I recall that Mr. Callow routinely rates his c41 a stop or so slower, but the colour palette he gets, while very effective for his imagery, is hardly neutral. I mean, check it out: it's great stuff he does, and his methods are his prerogative, but the rating has clearly shifted the colours to primaries. JD also experiments with x-processing and stuff so I think he will agree that he is broadly interested in, let's say, "non-neutral" colour renditions. Very interesting work.... but I'd assert that neutral colours are clearly not the aim of how he uses colour film. Perhaps he will chime in and come clean about his intentions with regard to literal colour
Dear Keith,
I'm having trouble interpreting your statement, could you please elaborate?
I mean, in the first sentence, it seems you're suggesting that, say, film rated at 200 ISO by the manufacturer should be exposed as if it were <100 ISO? How does that square with your second sentence?:confused:
Well, I just recommended a very wide bracket to get the feeling for what over /under-exposure does with c41 and with slide. The results are *totally* different with c41 than what you get with slide. As a general practice, when I start off with any new film, I shoot some brackets and decide how I want to rate the film in the future. And I almost always arrive at the conclusion that box speed gives the most neutral colour rendition. Nevertheless, I still sometimes
overexpose a print film or
underexpose a slide film to get a particular rendition. That is common practice.
Moreover, doesn't "overexposure" reduce colour saturation? I mean, for example, when photographing a sunset, a sure way to "bleach" the colours in the sky is to overexpose it: on the other hand, underexposure makes the colours richer (more saturated)
.
No, actually, [mild] overexposure of a c41 film
does not reduce saturation. "Mild"= +1 or +2 stops. Perhaps you have contrary intuition from working with slide or digital; for those two media, overexposure does indeed very easily wash things out and tend to make them go white on you. Colour neg film is quite different; try a few brackets and you will see. Overexposing colour c41 film by a stop or fractions of a stop tends to make the scene appear more saturated because it shifts the colours more to the primaries. In other words, you get less nuanced colours that appear more vivid.
Let's take a concrete example. Say, one of the 160 colour print films. If you rate it at ISO 160, at "box speed," then you will likely get the most neutral colours and most evenly tempered contrast, so to speak. In other words, highlight and shadow detail will be equally prioritized in all the colour channels.
Now, if you rate that 160 film at, say, ISO 100, then you are telling the camera that the film is actually a bit slower, so the net result will be overexposure of the film. This overexposure can do some good things and it can do some bad things.... it depends on what you're after. A number of people prefer to trade away the finer nuances of the more neutral colours for a slightly reduced colour palette, with colours tending to be closer to the primaries. The result, particularly in a landscape scene, can be more vivid definition of the colours. This
can be a desirable outcome, and a lot of folks do that (myself included) when they want that kind of result.
But... suppose that you want to do a portrait and you want colours as nuanced and true to life and (dare I say) literal as possible. Then you will not want to overexpose the film relative to box speed.
Please note (and perhaps you know already, but it is a widespread confusion) that overexposing and "pushing" are two different things. If you rate a 160 film at 100 but develop for 160 then you are merely overexposing it relative to box speed. That's all. But if you rate it at 100 and then adjust development time to "make up" for the implied lower sensitivity of the film, then you are pushing the film. The net result is very different.