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Brightcolours · 08-01-2013, 07:41 AM

Quote:Hi,

I am a photographer who uses Nikons Fullframe many years. But I also had experience with APS-C Nikons (D50 and D200). Now recently bought a Sony NEX-6 and I am enjoying it. I intend to purchase a wide angle lens like the 10-18mm f4 OSS (E mount).

I Compared the results of this lens in 10mm with the results of several Wide Angle lenses tested by PhotoZone. The comparisons included lens like Nikon 12-24mm, Nikon 14-24mm f/2.8, Nikon 16-35mm f/4, Canon 10-22mm, Canon 16-35mm f/2.8, Sigma 12-24mm and Sony 11-18mm. All tests were compared with cameras APS-C or equivalent and resolution MTF measurements.

I expected that a relatively inexpensive lens like 10-18mm OSS (compared to other Wide Angles) had much lower performance, because it is a lens for camera mirrorles (NEX-6). I was surprised to see that the MTF values at f/4 and f/5.6 were very good and in many cases even better than WA lenses on APS-C DSLRs with much higher value ($$).

Here is examples:
Sony
OSS 10-18mm f/4 E at 10mm f/5.6 Center=3521 and Border=2700 (MTF on NEX-7)
Sony DT 11-18mm f/4.5-5.6 at 11mm f/5.6 Center=2299 and Border=1631

Nikon VR 16-35mm f/4 at 16mm f/5.6 Center=2750 and Border=2452 (MTF on D7000)

Canon EF-S 10-22mm f/3.5-4.5 at 10mm
f/5.6 Center=2445 and Border=2248 (MTF on 50D)

You can not compare the numbers like that (well, you obviously can, but not in any meaningful manner Wink

). The numbers are related to the vertical resolution of the cameras the test was performed on. Since the vertical resolution on used cameras differs a lot, the numbers lose their meaning when compared to other cameras. 

Instead, just look at the bar heights in the graphs, without looking at any numbers. Or look at the "excellent, good" and so on legenda.

Quote:I know that many factors influence the quality of a lens, but should probably sharpness be the one that has a great importance. So, can I compare the quality of the lens for this parameter (MTF Resolution) to know if I will buy a sharp lens ?

No, not when you compare tests on different camera bodies. Like I said above, only look at the bar heights (without looking at the numbers). This will give a crude idea of how lenses compare.