Auto ISO in Manual Mode. OLY m43 system

Started Apr 5, 2014 | Discussions thread
OP Mark Chan Senior Member • Posts: 1,717
Re: Auto ISO in Manual Mode. OLY m43 system

G1Houston wrote:

dpreviewreader wrote:

This is a non-issue for those who shoot raw. Since exposure depends upon the f-stop and shutter speed only, shoot raw in manual mode, apply any exposure compensation by changing the shutter speed or f-stop and adjust the brightness during pp if the auto ISO selected is not what you want.

I would call this a work-around but not a non-issue. Even with the new sensor, the head room in the RAW files from m4/3 cameras is still limited so you can only push and pull may be 1-1.5 stops before the IQ suffers. I simply cannot understand why some many companies cannot fully implement auto-ISO in the M-mode with Exp Comp. Is there any technical reason why this is so difficult?

Maybe its the nature of the implementation?

When I tested this it was like this:

in A mode - you set the Aperture; the shutter speed tries to maintain speed above or at the classic shutter = Zoom X 2 minimum(??), then Auto ISO starts to move.

in S mode- you set the shutter speed; the Aperture moves to the lens maximum then auto ISO moves.

in M mode - the Auto ISO moves based on the relationship between your aperture and shutter; it attempts to maintain 'correct' metering, and only when the aperture / shutter setting is at the max will you see the ISO move toward over / under exposure territory. e.g. in dark indoor settings, I set f1.8 and dialed shutter from 1/8000 all the way to 1/15.  ISO moved from 6400 (EC at negative) all the way to LOW (EC at positive).  The picture's exposure did not change until it reached the negative and positive value areas.

The technicians may need to 'set' a base ISO' to allow for the camera to understand you need over or under exposure? Or a third dial to allow for exposure compensation?

One way to get around this 'may' be to set 'exposure shift' - i.e. you can set the camera such that the base exposure is maybe half a stop over exposed?

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