Should I get another lens? │ NEX-C3 & SEL30MF35 │ 30mm, ISO 1600, f/3.5, -1.3EV, Lightroom 4.2 Still debating the Sigma 30mm f/2.8. It's not super-fast, so no razor-thin depth of field. It's cheap (good for price) but also cheap (bad for build). It's just ¥16k (£125), which is an absolute steal for a brand new lens... and one with quite a reputation. It's got something of a cult following due to its impressive sharpness relative to the price of the lens. The kit lens is just fine (in my opinion). Zooms have a place in photography, and that place is convenience photography. I can go out all day with a zoom and never have to change lens. Wide angle to telephoto; it's all covered. However, there are obvious compromises when it comes to optical quality. Due to the increased number of parts and other artefacts (such as barrel distortion as a function of focal length); fixed length lenses (primes) tend to offer a better optical quality as they're optimised for only one focal length.
The Sony E mount Zeiss 24mm F1.8 lens is a thing of beauty. Optical quality is excellent. However, it's extremely expensive (¥92k; ~£700GBP). That's all well and good, but I won't be purchasing it on a whim. Its purchase will be a much more informed decision. Not so with the aforementioned Sigma. It's a bargain. I have almost enough loyalty points at the local camera shop to purchase this lens for the price of an evening meal... and the sharpness is extremely good.
I have a couple of manual focus lenses, which I love dearly. The first is my Voigtländer Nokton Classic 35mm F1.4 (shown in the picture attached to my NEX-7). I love this little lens. It's fully manual, beautifully made and exquisitely designed. I also have a very good condition Canon FDn 50mm F1.4, which is also a fantastic manual lens and I recommend it entirely (especially as used prices are so low). However, though manual focussing on the NEX cameras is a joy... sometimes it's nice to have a break and let the camera have a stab at focussing. It's always possible to add a micro adjustment or two, manually, should the situation arise. However, I don't have a lens with a super strong resolving power between my 16mm kit lens (which constantly gets slated online, though I like it a lot) and the Voigtländer at 35mm. The Sigma 19mm is also sharp, but I feel might be just a tad too wide for general out and about shooting - I could always just crop the 16mm shots a tad. I have two zoom lenses which both start at 18mm, but they are zooms and are best optically mid-range.
Now I've gone from sounding convinced I'll get the sigma to wondering if I can just make do with the zooms and their image stabilisation (great for low-light handheld shots). But then, the sigma isn't much money at all. I hardly use the macro lens with which I took the above picture; it needs to be restrictively close to the subject in order for it to fill the frame (thus hard to take pictures of animals/insects/anything not a tree). Any, I forget what I was rambling about now. I'll probably get the Sigma as it's not so much money and seems to have some rather impressive detail available.
However good a lens or imaging sensor is, though - the most important role in photography will always remain behind the camera.