Olympus E-PM2 Actual ISO vs IS0 set in camera?

Leo wrote:

sigala1 wrote:

Leo wrote:

I am sorry to start the well beaten subject...

I have two 4/3 cameras: Olympus E-PM2 and Panasonic GX1. On ISO graph by dxomark.com for these two cameras the E-PM2 actual ISO is about half of what it set in camera (for ISO set to1600 the actual ISO is 800), while the actual and set in camera ISO for GX1 are equal. All the above measurements apply to RAW settings as DXO test the sensor.

As I have two cameras one, which perfectly match the set and actual ISO (GX1) and one with the actual ISO only half of the set ISO, I decided to test if there is any difference in the exposure between these two camera.

I have set the cameras to the same ISO, aperture, expose compensation and exposure metering and photographed the xRite White Card filling the viewfinder. The two cameras showed identical shutter speed. I have opened the images in the Lightroom and the RGB readings for both images were the same within few percent points difference.

I do trust DXO, however … my test does not follows the DXO statement.

Leo

All cameras should give you the same JPEG exposure at the same ISO.

However, Olympus ISO 200 is really ISO 100 underexposed by a stop, which Olympus has done intentionally to make sure that the photos don't have blown-out highlights.

Hi sigala1,

I am so glad you have replied for this post also, as now i you may see my replays for sure and help to understand the problem. If Olympus cooks the RAW file then probably this adjustment can be considered as a part of the sensor activity as from the outside that is all how I can interpret it. I have checked the noise level and resolution (just evaluative) at ISO 3200 and found that PM2 is about the same on the noise and resolution matters as my D7000 at D/A set to 12 bits. Also D7000 with the lenses is too heavy and big. I am on the older side Copy of my 4/3 reply is below.

Thank you for reply. I was expecting different exposures, however exposures were the same. I have run the test as now thinking to purchase Olympus M1.

I photograph only in RAW format. My all three cameras, the two mentioned in the post and Nikon D7000, are permanently set to RAW. I use D7000 mostly for photographing art, like paintings, for artists because D7000 allows 14 bits A/D conversion. This camera profiled for different ISO and lighting conditions. My experiment in the post performed with cameras set to RAW. Imaged were opened in Lightroom.

Leo

The raw file isn't "cooked," rather the raw file contains instructions for the correct exposure for the state ISO. Adobe Camera Raw has a +/- exposure slider if you would like to change that.