Comparing shots of the camera with the smaller sensor (the Oly) with those of the camera with the larger sensor (the Nikon ) means that you have to increase the focal length of the camera with the larger sensor.. which is what I did by zooming in the Tok a bit... from 10mm to 12mm, .I was also surprised by the difference in sharpness. Like the Tok/Nikon was not focused correctly..must check this out by using other autofocus settings..
Yeah, I understand why you went to 12mm, but 11mm is closer. 11*1.5 = 16.5. 8*2 = 16. 12mm is effectively 18mm full frame and you can see the focal length looks different between the two lenses in your photos. I'm a picky devil ain't I?
But the difference in focal length is probably not the biggest factor. When comparing between two different crop sensors, you must adjust the aperture. If you don't the field of view and thus the focus will be different.
"As sensor size increases, the depth of field will decrease for a given aperture (when filling the frame with a subject of the same size and distance)."
By using the same aperture on both lenses, you are allowing the 8mm Panny to have a wider field of view and that likely will improve sharpness of the image. Also, since you are using JPEG, I can see in the first photo a bit of a "halo" on the edge of the banana which to me means it's slightly over sharpened. Did it come straight out of the camera like that?
Anyway, I don't mean to harsh on your methodology, I'm just being a pain because I'm interested in your results I own both a D7000 and an Olympus OMD, but I don't have the Panasonic 8mm lens yet. I will say on my Tokina 10-17 the sweet spot seems to be right at F8 and 10mm, but that's because I have AF tuned it to be sharpest at 10mm. Zoom lenses are always a bit of a compromise.
Edited by johnspierce, 13 November 2013 - 02:05 PM.