X-Pro1 images dark (underexposed)

Besides shutter speed, ISO and aperture there is another factor that can influence the results: the lens elements. Depending of how many elements (pieces of glass) and coatings are between the lightray coming into the lens and your sensor, the results you get may vary.

So as per definition: The lens aperture (f-stop) is the ratio of focal length to effective aperture diameter.

This does not incorporate loss of light due to amount and quality or thickness of lens elements.

Cheers,
Smatty
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