Part 2: DSLR lens

In previous part, i've talked about the major specification that will affect the price of one lens. So here, again i will talk about the minor specification (extra feature) that could affect the lens. These extra features are important based on the what type of lens that you want. Features that i'm talking about are: 

Silent Autofocus

Silent auto-focus is useable for photographer that want to capture the wild life.They need a silent lens zoom. When the lens focusing on the subject, they eliminate the noise of grinding. Thus, it create a silent focus.Basically, this feature is commonly known as Ultra sonic motor (USM) and Hyper sonic focus (HSF).

Full time manual focus

Usually,when we do need to use Manual focus, we have to switch it on. But here, there are special lens that no need to switch on the Manual focus. These types of lens also have ability to focus automatically, but still, you can adjust with manual focus.

Internal zoom 

When the lens focus form wide angle to telephoto, the lens-which have external zoom, will increase the length. However, with internal zoom, the lens's length didn't change. The advantage of internal zoom are these lens focusing faster and smooth compare to external zoom. These lens also does not effect the balance of camera when standing on tripod. 

Image stabilization

Maybe some of you did notice about this one. In Canon, it's known as Image stabilisation (IS) while in Nikon, it commonly known as Vibration reduction (VR), With this feature, the blurry picture can be eliminate thus creation clear shot.

Superior optic

Some of the lens are created with special optic adjustment for distortion, reduce flare and stray light from the lens. As a result, it produce image with maximum clarity. It have different name, for example, Canon branded it with 'L' while Nikon are branded with 'ED'.Anyhow, these lens usually expensive at the market.
So, let me try some example:
From the description, this have silent autofocus system (AF-S), then ED is reffer to superior optic, and VR for vibration reduction. The focal length is 18-200mm which is wide angle to telephoto. No wonder the price is high.