Today we're gonna do a quick comparison of Sony'e E 30/3.5 Macro lens against the new kid on the NEX block, Sigma's 30/2.8 EX DN lens. Sigma has just released two dedicated primes for the NEX systems (also available for the m43 platform) and based on the initial feedback from the user community, the new 30/2.8 EX DN is quite a performer. But really, how good of a performer? Let's check it out...
But first thing first. The two lenses are really targeting different segments of users - Sony's lens is a 1:1 macro while Sigma's lens, well, it's just a general purpose lens. If you're even remotely interested in macro photography, this comparison is useless to you - just go get Sony's lens. On the other hand, if you were considering getting Sony as a general purpose prime (given it's EFOV of 45mm, you get a normal-ish lens), than read on - you're the primary target for this review.
Even before we compare the actual resolution, vignetting etc. numbers, Sigma already holds an advantage over Sony - it's cheaper, lighter, smaller and faster. Sony sports slightly better build quality with aluminium barrel, but Sigma's barrel is just fine as well - I managed to bump the lens a couple of times and it does not show any damage. It's not clear how well either of the lenses would survive a fall from say 3 feet, but whatever - few lenses would survive such a fall anyway.
A little bit about the test:
Looking at the resolution numbers out of Imatest, one thing becomes clear - Sigma holds a lead over Sony in corner quality. Center image quality is very similar - there's a bit of pull and push here and there, meaning that each of the lenses claims minor lead at one or another aperture, but the differences are so small, that we can call it a complete wash. Borders is where the difference is more noticeable, with Sigma producing constantly better results in the range of 20-30% throughout the aperture range.
Lateral CA, according to Imatest, is a wash with these two lenses - both produce moderately high CA around borders, and neither holds a clear advantage.
Sigma has a slight advantage here simply because by f/4 we already stopped it down by one f-stop, while for Sony this is pretty much its widest aperture. Both lenses vignette at the widest aperture setting.
Distortion is basically non-existent in either of the lenses - ~0.4% barrel distortion for Sony and ~0.3% barrel distortion for Sigma, neither would be visible in real life use.
And there you have it - Sigma's entry level prime indeed bests Sony's lens in resolution department. Everything else seems to be very comparable. So the recommendation is to choose Sony's E 30/3.5 if you're into macro photography, while for everything else just go with Sigma's 30/2.8 EX DN.