Olympus OM-D EM 5 Mark II - RAW in Manual/ Aperture / Program mode

Started 11 months ago | Discussions thread
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hcjghr New Member • Posts: 11
Olympus OM-D EM 5 Mark II - RAW in Manual/ Aperture / Program mode


This question is regarding RAW files and how the values are affected when different camera modes (P/Av/Tv/M) are used. I'm working with the Olympus EM5 Mark II camera.

Through some experiments I have noticed that raw values (after black level subtraction) are not consistent when taken with different modes.

The clearest example is if I take a photo 3 photos one after another in a controlled environment (no light except a LED light) using

- P mode (where camera sets the Aperture and Shutter speed)
- Av mode (selecting same aperture and camera sets the same shutter speed)
- M mode (selecting same Av and Tv setting)

Looking at the mean values of patches I noticed that images from P and Av mode are consistent while M is different (images taken from same position in same conditions):

Manual (M) mode:
Mean: 0.14235, 0.15051, 0.01841

Aperture priority (Av) mode:
Mean: 0.15901, 0.16807, 0.02075

Program (P) mode:
Mean: 0.1605, 0.16968, 0.02098

( I have more than just this example)

In another example I was changing the light intensity to force the P mode to adjust parameters and I noticed that RAW seems not to be affected by change of shutter speed in P and Av modes while is clear that M mode performs as predicted from my settings.

As it seems the camera in P and Av mode either does not take the acquisition with the parameters it records in the exif of the file or there is something else that I'm missing.

I've also uploaded the three ORF files so if anybody want to have a look:

I hope I more or less explained well enough the problem!
Any insight would be great!


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