Effect of shutter speed on saturation

[Dave Humphries]

I think this myth has arisen due to the fact/theory (take your pick ) that how we remember a scene is actually different to how it really was if measured photometrically.

It is a fact that at lower light levels, the (colour) cone sensors in the eye are less senstive to light compared to the monochromatic rod sensor. Thus in twilight, or moon light, we largely 'see' in monochrome (except the brain doesn't know that) because any bright light, like an orange sodium vapour lamp WILL trigger the cones and we do see it in colour.

The crux of this matter is that we walk away remembering a low saturation scene, then, when we see the photographs at standard viewing luminosity, the (more) faithfully recorded actual saturation levels appear greater than our memorised ones, thus we could, erroneously (IMHO) 'explain' this as it being the longer shutter speed gave us more saturation.

I am only considering shutter speeds in the range of 1/10s to seconds here; not Colin's habit of exposing several minutes in (naked eye) pitch black and coming back with a fabulous 'sunset' picture - because that's obvious to him, but it is the same thing really. Not withstanding Colin will PP his shots and may boost saturation, unless you knew, anyone that wasn't there at the time would just assume he had shot it earlier in the evening when we see colours in the sky like that ourselves occasionally (while they are still bright).

That's my pet theory, YMMV.

Cheers,

[I Simonius]

Varying the exposure has a BIG effect on saturation because all colours wash out more the higher the tone level (past an "ideal point"). Polarisers sure help - but - they give uneven effects on wide angle lenses (and also contribute to vignetting and/or outright obstruction with WA and UWA lenses where there are other filters also being used).

which was why I said that the important thing is to get exposure (not just 'shutter speed') bang on. By bang on, I mean optimised for saturation.

With slide film this usually meant, in my experience, spot metering and underexposing by half a stop.

With digital it is still best to spot meter for the specific coloured area, but whether there's any advantage in over or under exposing (shutter speed irrelevant) I very much doubt. Probably better to adjust in post processing.

Polarisers will help saturation in sunny/well lit or wet (water) conditions but with the WA provisos already mentioned by Colin.

The other proviso I would add for polarisers is that you may actually need to slightly overexpose for polarised skies to counter the increase in noise in skies from use of polarisers as they tend to slightly underexpose the sky, hence the blue and noisiest channel.

Either way, I can see no valid arguement to support a thoery where the shutter speed alone affects colour saturation - so I would reiterate what I said previously: that the idea that shutter speed (alone) affects colour saturation, is completely unfounded

[Benboxer]

This is all great stuff! I can appreciate everyones viewpoint on this! Eno mentioned that higher ISO will create the impression of higher saturation due graininess. This especially applies to my photos, as most of my pics shot at ISO 800 and 1600 (no flash) suffer from the graininess inherent in smaller film sensors (I shoot with a Fuji S8000fd P&S). I've always wondered if my shooting habits would change if I used a DSLR with a more sensitive ISO. It's a great question I always ask myself. I thoroughly enjoying the learning curve involved with this discipline!