OM-D: The case against Auto ISO

Started Jul 4, 2012 | Discussions thread
MrSynthetic Forum Member • Posts: 54
Re: or use at M mode with Auto ISO (nt)

This won't let you compensate exposure:-(

Oly need to either allow individal setting of min shutter speed in auto iso OR (my favourite) allow exposure compensation in M mode!

radix1 wrote:

Thomas Niemann wrote:

The algorithm for adjusting exposure in decreasing light using aperture priority and auto ISO is as follows:

1. shutter slows down to a predetermined limit
2. then ISO goes up to max ISO (menu E: ISO-Auto Set)
3. then shutter speed goes below predetermined limit

For the Olympus 45mm f/1.8 lens the predetermined limit is 1/(2FL) or 1/100.
For the Panasonic 20mm f/1.7 lens the predetermined limit is 1/(3FL) or 1/60.

With IBIS it's easy to take sharp hand-held images at much lower shutter speeds. So we're boosting ISO and degrading image quality when we could achieve several stops of improvement by simply slowing down the shutter speed sooner.

Perhaps they could add a menu option that lets you select the shutter speed lower bound. e.g., 1/(2FL), 1/(FL), 1/(0.5FL), 1/(0.25FL). And, in the Olympian tradition, refrain from explaining this feature in their user manual.

Meanwhile, the workaround is simple. Don't use Auto ISO. When you set a specific ISO value the algorithm is as follows:

1. shutter speed goes down

That's it. So just keep an eye on the shutter speed and open the aperture or increase ISO as needed.

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