Analysis of Noise in Casio Exilim EX-Z750
I’ve conducted a more thorough analysis of noise phenomena in my Casio Exilim EX-Z750 ultracompact digital camera.
I’ve observed that noise at fast shutter speeds (1/8+) at ISO 50 or ISO 100 is minimal. Unfortunately, this leads to potentially underexposed images when shooting in low light indoor conditions.
As is typical with digital cameras, ISO 200 and 400 are rather noisy. I had previously thought that the ISO 400 mode on the Z750 was particularly bad, but empirical test shots don’t prove that out; it’s noisy, but no more so than my PowerShot S60.
The interesting observations came at slower speeds. I shot a few exposures with a 0.3 second shutter, running the ISO gamut from 50 to 400. I found that, even at ISO 50, I was seeing some noise artifacts! This makes sense to some extent, as the longer the shutter is open, the longer noise effects have to accumulate, however it is somewhat unfortunate for me, as I use slow shutters to expose portraits in low light.
I also played with the exposure compensation control. At 1/6s shutter, ISO 50, setting the exposure compensation to its max value of +2.0, I got an image that was actually somewhat overexposed compared to the 1/8s ISO 100 shot, and yet had less noise than the 0.3″ ISO 50 shot. Now, obviously, exposure compensation doesn’t help with blur the way a fast shutter does, but 1/8 is hardly fast enough to eliminate blur anyway.
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