18-55 kit lens at 30mm vs. Sigma 30mm F2.8 prime - I can't see any difference

Started Oct 4, 2012 | Discussions thread
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Elyharbour Senior Member • Posts: 1,666
18-55 kit lens at 30mm vs. Sigma 30mm F2.8 prime - I can't see any difference

The usual wisdom here is that a) the Sigma 30mm is a very good lens (agreed) and b) it's often implied to be better than the kit lens at the same focal length (not agreed).

Having had some sharpness issues with my Alpha lenses, I now have a standard "test" wall which is the façade of an old Victorian orange-red-brick building with windows and lots of complex detail. It's also reasonably symmetrical from side-to-side. This is nicely lit by the early morning sun, but also includes shadows. It clearly shows the shortcomings of the Sony Alpha kit lenses, and even the 35mm 1.8 prime on my A200 is not perfect.

So back to NEX. I tested my NEX 5 on the same wall this morning - E-mount 18-55 kit and the Sigma 30mm prime. Two immediate observations at 100% when I got home:

a) Both gave excellent results and very consistent sharpness from edge to edge and corner to corner across the frames.

b) There was no discernible difference between them - sharpness or CA.

I did some other shots across the bay at 90deg. to the sun - same result. I could just about argue that the 18-55 kit was very marginally sharper at F8...but that's splitting hairs.

Now, I also know there are lots of QC variations in lens, and I don't know how mine rank against the norm in this respect...but do these results surprise / not surprise others who have done similar tests?

 Elyharbour's gear list:Elyharbour's gear list
Fujifilm FinePix X100 Fujifilm X30 Canon G9 X Fujifilm X-T1 Fujifilm XF 18-55mm F2.8-4 R LM OIS +5 more
Sony Alpha DSLR-A200
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