September 27, 2013

Metabones Nikon F to Fuji X adapters – part V

Playing like the big boys…

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TEST TWO: image sharpness – the hard way

“Natural” scenes, like the one in our first test, do not always have very sharp edges or high-contrast areas. That is why professional testers use dedicated high-resolution test targets, such as the widespread ISO 12233 chart.

I do not have a full-size “original” for this target, but some wed searching led me to a 18688x1168 pixel file: good enough to make an A4-sized print on photo paper (with my modest HP Photosmart office printer). Obviously a target of this size, resolution and quality will not allow to capture a lens’ true performance “by the numbers”, but it might do a reasonable job when comparing images shot with the Speed Booster, with a regular F- or G-adapter, or with a D700.

The (too) small size of my ISO 12233 copy forced me to at very short subject distances, with a narrow DOF, with hard to control parallelism between sensor and target, and suffering from the not-so-flat flat field reproduction by many lenses. Most lenses (unless designed for repro or macro photography) furthermore will not reach their optimal performance at nearby shooting distances.
So I limited myself to comparing two local areas, one in the center and one closer to the bottom left corner, as indicated on the target image. I also opted to shoot each lens at one f-stop down from fully open, to reduce some of the effects mentioned.

For this test as well the camera was repositioned when changing lens and adapter configurations to keep a more or less equal subject area covered.


Testing the Nikon AF-D 50mm f/1.4



Not too bad… we surprisingly see an improved performance with Speed Booster also in the corner.

Testing the Nikon AF-S 50mm f/1.4G



Same finding here: about equal in the center, improvement in the corner.

Testing the Nikon AF 50mm f/1.8



I also compared with the image quality when using this lens on a D700:


Testing the Nikon AF-D 85mm f/1.8



Testing the Tamron 90mm f/2.8 SP Di Macro

I was curious to try my favorite macro lens: I know it has excellent sharpness across the frame at close distances, but it also has a very flat field reproduction. And that shows in these samples:


 NEXT: More and different image quality tests

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