ISO 100, OMD-EM1II and firmware 3.0?

Started 2 months ago | Questions thread
MEDISN Contributing Member • Posts: 815
Re: Meaning of base vs. extended ISO

bobn2 wrote:

I'm not sure which DxOmark measurements you're talking about. Whilst they make some errors, overall they are quite good. It's just understanding what the actually signify. Their 'measured ISO' measurement is actually very useful indeed, it's just misnamed. It isn't 'measured ISO'. A better name would be 'saturation exposure', where the measurement of exposure is a non-standard ISO rating.

Can we apply this to an example (Em1mkII) Bob?

The "saturation exposure" of DxO is 83

The lowest ISO settings on the camera are now 64, 100, 200, with 64 and 100 labeled "extended" or "low" in camera.

Help me with these scenarios:

  • If I set camera ISO to "64" I am over-saturating what the sensor can likely handle and risk blowing highlights (clipping).
  • If I set camera ISO to "100" I might just avoid blowing most highlights
  • If I set camera ISO to "200" I am providing ample headroom for highlights (wasting exposure latitude, i.e. less signal in the shadows)

If these statements are accurate, it would seem the ideal "Low ISO" setting would be 100...perhaps with even +1/3EV exposure compensation.  I realize all scenes/environments are not equal but IN GENERAL, am I close? 

Thanks in advance.

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