Last June during the Migrant Workers' Day at Oji Park, I brought along with me my DSLR kit but got frustrated because I couldn't 'reach' my subjects. As expected on events like this, the place would be filled by a lot of people, each and everyone representing different characters.

The kit lens (18-55mm) having a max focal length at 55mm would be too short to do some candid street shots. Thus, I had been dreaming for a longer lens eversince.

Option 1: All-around lens
For my next lens, my first choice then was the Nikkor 18-200mm VR. It's a very popular Nikon lens because of its versatility (from shooting wide to long), capped with a Vibration Reduction system (for those shaky hands) and the benefit of not having to change lenses making it a perfect travel companion (always ready to take a shot of the scene -- near or far).

The downside: Price, as it sells for 68k-88,200 Yen on major commercial stores (approx: Php28-36k). Also, minimum aperture ranges from f3.5-5.6, so if you are dreaming of some creamy bokeh in the background, better get those prime lenses.

Option 2: Prime Telephoto Lens
I did wanted to have the bokeh effects, and so I realized I should get prime lenses instead. Prime lenses have wider apertures than the zooms, allowing more light to enter; thus, producing beautiful bokeh. However, you'd get stuck with only one focal length (no zoom). Nikkor's available prime telephotos at my desired range was the 105mm and the 135mm. Using a D40x, my choice of lens were limited because only AF-S lenses would autofocus on it.

Option 3: 3rd Party lens (Sigma)
Nikon is an optics company and has been producing great lenses eversince (one can notice how expensive their lenses are); thus, I had some sort of bias against 3rd party lens makers (Tamron, Sigma, Tokina). However, having some time searching for my next lens, I came across Sigma's 50-150mm DC and quite became interested with it due to its rave reviews. Eventually, it had been my choice in the end.

What I liked about this Lens:
Fixed maximum aperture width at f2.8 (from all zoom levels 50mm-150mm). - This would satisfy my bokeh cravings, one thing that my kit lens couldn't do except at the wide end (18mm @ f3.5).
Focal Range: It's just quite enough for what I need, perhaps for event/street photography. I didn't want it to be too long.
Internal Focusing: Zooming from 50-150 wouldn't increase/decrease the length of the lens. Unlike the 18-200mm VR where it goes longer and longer till it reaches 200mm.
Weight: This is considered a lightweight in terms of its capability (fixed wide aperture zoom lens)
Sigma EX: It's an EX lens, somewhat being one of the 'elite' Sigma lenses. Much like Canon's L version of lenses. Of course it's not just labeling, it's more of the build quality that makes it an EX.
HSM - HyperSonic Motor... Sigma's way of telling that it autofocuses with my D40x and it's fast and silent.

I only wish it has VR, but hey it would just ramp up the price anyway. Lowest price one could get (bnew) would be 82k Yen. Since I don't want to shell out that much money, I opted for the practical route: buy 2nd hand. Japan's Used Camera market is great, that one can find used gear at a relatively low price, most of which are still in near mint condition.

I know, this hobby proves to be costly but at least I made it at 6 months with my kit. Some people I met here would buy new gear almost every month. I'd still be using my kit once in a while when I would be needing a wider lens (close range shots). I guess I should have added that to my why I like this lens list.

Sample shots, check out the Pictures Section. (Kasukabe Natsu Matsuri Day 2)