Auto ISO in Manual Mode. OLY m43 system

Started Apr 5, 2014 | Discussions thread
GeorgianBay1939 Veteran Member • Posts: 4,018
Re: Why no Ev compensation with Auto ISO in Manual?

purpleray wrote:


Tech wise, I am a beginner and need advice on the issue of auto ISO.

I am a full beginner, not just tech-wise!

WHY AUTO ISO is important for me

I have been taking photos with some seriousness for over 40 years and so from my film days have a basic understanding of F stops, Shutter Speed and ISO and the relation between these in a given amount of light - EV's.

Now after many years taking casual photos of my kids growing up, I got a bit serious through taking photos of school musicals and then onto community opera and musicals and some occasional professional opera and musical groups.

Using 4/3s and now m4/3's, a bit of attention needs to be paid to exposure due to the high DR of theatre and often low light in significant parts of shots. So DR and low light sensitivity and ISO range are important issues for my photos.

I used to religiously stick to ISO 800 or ISO 1600 ( the highest I could set the camera) when I used E510 and E520 to address these issues. I would set F2.8 or F4 depending on the scene and move the EV compensation according to the scene, quite often -1.7EV to compensate for bright lights on leads. I used to look at the changing light and scene and flick my EV dial accordingly. I did have to address noise on the chorus and set quit often - the chorus and the production people were big buyers of the photos - so I couldn't just focus on the leads but had to show the whole context and scene.

With the E620, I tried Auto ISO and found that while some shots might be ISO 3200, most were less than ISO 800. I still judged the light myself and constantly reset exposure through the EV dial.

Why Manual and auto ISO with EV compensation is important

Now the problem is that I have no control over the algorithim that sets ISO v changing shutter speed. So sometimes the shutter speed is too low for the F stop I have chosen to match the DOF needed for the scene.

So Auto ISO with Manual F stop and shutter speed and with EV compensation is what I've been looking for.

So when you all seem to agree that there is no EV compensation any more - I am in grieving and I don't understand. I need the EV compensation so I make the final decision on exposure.

I do not agree with those who say EV comp is unnecessary if/when using AutoISO in M(anual) Mode --- in the cameras that have AutoISO in Manual.

How I thought Manual, auto ISO and Ev compensation would work

I imagined that with auto ISO and Manual, EV compensation would change the autoISO set for a particular shot.

Right.  Set f/, shutter interval according to DoF and Motion Blur requirements.  Use EV C to "correct" AutoISO from its normal algorithm.  How you use EV C depends on your compromises between noise, highlight protection and pushing darks in software OR with ISO gain.

Let's say I set F4 and 1/250 manually, the cameras metering would use the autoISO to say ISO800 would give the correct exposure for a particular shot. From my experience and view of the scene, I decide -1.0EV would be better and so flick the dial. I imagined that the camera would then set ISO400 instead. So I would get my manually set F stop and shutter speed and using autoISO, I would override the cameras metering and get ISO400 instead of ISO800.

Why are my imaginings wrong?



I don't think that there is anything wrong with your thinking.

I shoot panny, RAW, and Manual when in situations where I have high scene luminance range.  I set f/ and shutter interval, then ISO,  working up from base as required since I have no Auto ISO in Manual.  I use my histogram as my primary exposure aid (since I don't have Olympus style blinkies).  My objective is to get as much data into the RAW file as  possible, usually ETTR while preserving highlights.

If I were in a quickly changing scene luminance situation it would be nice to let the ISO float in "Auto" according to some algorithm IF AND ONLY IF I could change that algorithm with EC.

Ever since I started shooting RAW, I am no longer wedded to the Exposure Metering Equation , but choose to set exposure following my familiarity with my histogram output, the type of metering I am using and my experience with how much I can pull/push a RAW file in Lightroom 5.3.

Works for me.


PS   I started to shoot RAW when I wanted/needed maximum DR from my images at minimum noise.   It was then that I read gollywop and decoupled myself from the Exposure Metering Equation.  Although the divorce was rocky at times it worked out for the best in the long run.


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