I'm received my first m4/3 camera and lens in the mail less than 1 week ago. It was a lazy slow Sunday, finished some cleaning of the house but was now sitting in front of the computer. Decided to compare my shiny new E-M1 to my trusty old 5D2 at high ISOs. Olympus OM-D E-M1 w/ 12-40mm f/2.8 Lens - Shot at 18mm, f/8, ISO 1600, 3200, 6400, shutter speed varied according to ISO. All tripod shot with 2 second delay release. Canon 5D Mark II w/ 16-35mm L f/2.8 II Lens - Shot at 35mm, all other settings exactly the same as above including the varied shutter speeds. All 6 pictures are shot in raw, imported into Lightroom 5.3 RC. I did a quick crop, as close to 1:1 as I could eyeball it, and synchronized the crop box across all 6 photos, so the % crop should be the same between the cameras. There was slight discrepancy in framing between the E-M1 and 5D2 due to aspect ratio/height of the camera+lens setup, etc. WB was quickly adjusted using the "eyedropper" tool, and also synchronized across each camera (so the E-M1 shots are WB sync'd with each other, 5D2 shots are WB sync'd with each other). All 6 crops were then exported in jpegs, and then put side-by-side in Photoshop. Lastly, I did a quick noise reduction adjustment and sharpening adjustment in Lightroom on the E-M1 6400 file. I synced the exact same noise reduction/sharpening settings to the 5D2 6400 file and exported those. Here are the results, hope these are interesting for you to look at : I wanted to see how much of an advantage a 5 year old FF sensor had over the E-M1, so I put a few different ISOs side-by-side for easy comparison: Larger image sizes are available here: http://www.flickr.com/photos/111013175@N04/sets/72157638495573976/ EDIT: Looks like the images shrunk quite a bit after posting.. details are easier to see in the larger images. To me it looks like the 5D2 images are cleaner across the board but only slightly so. Less than a stop advantage I think.