08-01-2013, 07:41 AM
Quote:Hi,<b>You can not compare the numbers like that (well, you obviously can, but not in any meaningful manner
<span>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).</span>
<span>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.</span>
<span>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 ($$).</span>
<span>Here is examples:
Sony
<span>OSS 10-18mm <span>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</span></span></span>
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)
). 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. </b><b>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.</b>
Quote:<span>I know that many factors influence the quality of a lens, but should probably </span><span>sharpness </span><span>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 ?</span>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.