This test today will simply be about sharpness. Specifically, sharpness in the dead center of the frame. I may do subsequent posts where I examine edge sharpness (though this is of limited utility on Micro 4/3, since the 8 adapted lenses are all intended for use on 35mm film, and so I’m still in the middle of the lens when I’m at the edge of the GH2 sensor.) I also may very well do a subsequent post on the bokeh, or out of focus rendering, of the lenses. However, I didn’t have time for that today. Plus, since none of these lenses really compete against each other, I didn’t feel the need to examine every aspect of these all at once. This is just for fun, and I was curious.
Each lens was mounted with an appropriate adapter on my Panasonic GH2, save for the Petri, which doesn’t have an adapter. I solved that by holding it inside the OM adapter, which allowed for flush mounting and sealed light. Since exposure was by flash, I didn’t have to worry about moving the lens accidentally during exposure. The Panasonic GH2 is sort of a torture test for lenses. Because of Micro 4/3 smaller than 35mm size sensor, and the GH2’s high resolution, it really demands every single ounce of resolution out of a lens. Lenses that appear very sharp wide open on a full frame DSLR may look quite soft on the GH2. A lens on a full frame body might require 40lp/mm to be absolutely razor sharp. On the GH2, you may need a lens to hit 80lp/mm to be razor sharp.
The target was the top of my Transportation Corps beer mug, which has fine metal detail and I thought would be good for seeing small differences. The whole frame also has a leather bound book to the left, which I will likely use when I examine edge sharpness in another post. (I’ll take new shots to examine bokeh). As you’ll see in the crops, the texture on the seal is odd…it almost makes everything look soft, but it’s just the way the facets and texture are, as you can see by the fine strong lines against the red.
With wildly disparate maximum apertures, I had a few options to examine them. Wide open, then all at the same aperture, or wide open and a certain number of stops closed down. I chose the latter. Since most lenses tend to be at their sharpest about two stops closed down, I took shots both wide open and two or so stops down. For stopping down, I stuck to whole f-stop numbers to make it easier, so the lenses are actually between 2 and 2.5 stops closed down (f/1.8 lenses did f/4 on the second shot, for example)
These are all 100% crops, shot in RAW and converted with Lightroom 4 Beta. They have had identical processing. The camera was tripod mounted. Native Micro 4/3 lenses used autofocus directly on the focus point. Adapted lenses were manually focused using 10x live view to ensure precise focus. The lighting was done with off camera flash through an umbrella, and just used TTL metering via an off camera shoe cord. As a consequence, each of these lenses metered a bit differently, depending on the aperture used and the design of the lens. So, you’ll see some varying exposure. However, since I am examining resolution, not color or contrast, I don’t really care if there’s some variation in exposure.
On to the results…please click the image to see the crops at actual size:
Observations / Conclusion
Well, for center sharpness, there are some interesting conclusions.
Wide open: One can see right away that the native Micro 4/3 lenses win this round handily. This isn’t surprising since they are designed for the smaller image sensor, and thus designed for maximum resolution over a smaller area. What is somewhat surprising is that wide open, the Olympus 40-150mm zoom appears to my eyes to be the sharpest lens of them all. Now, granted, it’s at f/4 while the next closest, the Olympus 45mm f/1.8 is at f/1.8, but still. Impressive for a cheap zoom. Of the adapted lenses, the Canon FD 50mm f/1.4 looks to me to easily win out, followed by the OM 50mm macro, FD 50/1.8 and Hexanon 50/1.7. The Hexanon 57/1.2 is showing its dreamy self wide open and the Petri 55/2 also has a similar look wide open.
Stopped down: The Leica 45mm f/2.8 appears to be tops here, with the Olympus 40-150 and 45mm f/1.8 extremely close behind. The manual focus lenses have caught up quite a bit here, though, with the Hexanon 40mm f/1.8 and 50mm f/1.7 running right with the Oly 45/1.8. The Canon FD 50mm f/1.8 is sharper here than its f/1.4 brother, the opposite of their performance wide open. It can be noted that all of these lenses stopped down are capable of excellent resolution. Edit: I have looked over these crops again after this article was originally published, and looking even more closely, I think the Leica 45mm f/2.8 Macro is actually the sharpest in the center stopped down. I have edited the conclusion to reflect this.
Well, that’s it for center sharpness. Go on to Part 2, where I look at edge sharpness.