@ternst - Are you using Capture One or another program for your raw processing? While I use a variety of raw processors myself I *strongly* suggest that Capture One (specifically 4.1.1) be used for processing long exposures. I agree "no noise" or "noise free" is a marketing-only phrase. However, using ISO 50 on a reasonably cool night and processing in Capture One I find the long exposure capability of the P45+ to be truly astounding.
@gjazzz - the device separates the camera/lens from the sensor. You then activate the sensor and do whatever you'd like with the camera. This allows you to for instance shoot 10 exposures at 1/125 each with a strobe pop. Or you could mix multiple strobe pops with several long shutter-only exposures. Etc Etc. When you are done you turn off the sensor. Phase files won't start to accumulate noise for many minutes (or hours depending on temperature - see temp-to-time link in paragraphs above) which makes them uniquely able to do this sort of experimentation. I don't know that camera well, but the "multiple exposures" on the S2 is almost surely just digitally adding the exposures the same way you could do in Photoshop.
In general:
1) Long exposures in digital are highly dependent on ambient temperature and sensor design. The Phase One max exposure times are shown on our website here:
http://www.captureintegration.com/phase-on...one-tech-specs/2) I 100% disagree with the assertion that negative film is the way to go for long exposures. My
thesis was on time-lapse photography. I spent many hours in the middle of the cold Ohio winter night doing long exposures. The end product only used 30 second exposures, but along the way I shot much longer exposures.
The reasons I put forth that digital is much better for long exposure are:
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No reciprocity failure. Star trails won't fade, and exposure calculations are strait forward.
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Easy/Accurate estimation of proper exposure even in very complex scenes. Scenes including both moonlight, artificial light, and areas of important shadows are next to impossible to analyze with a light meter. Instead of bracketing film at the cost of hours of exposures, a single digital underexposed-and-pushed image can give you an exact exposure which can be verified immediatly after.
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Easy path to HDR (whatever its form) for scenes with inherently extreme contrast.
However these arguments do fall apart if you're targeting an 8 hour exposure :-). So if that's your idea of a long exposure then by all means, film is the way to go!
Doug
Capture Integration, Phase One DealerPersonal Portfolio