Comments about Pentax 16-50mm f/2.8 ED AL[IF]SDM Wide Angle Zoom Lens:

I bought the Pentax DA* 16-50mm f/2.8 as the first lens for my Pentax K-7. It takes high quality images throughout its operation range. I like the color and image sharpness. Make sure to use high optical quality filters to get the most out of the lens. The constant f/2.8 aperture is nice to have in a zoom lens for lower light conditions, where you cannot use a flash. Makes for a brighter view finder too. This is a weather resistant lens which makes it easy to take along to get the shots you want regardless of the weather. I have used the lens on a rainy hiking trip and during windy ~15 F weather while skiing. If only Pentax made their DA 55-300mm f/4-5.8 lens weather resistant... it would be on my wish list.

The auto focus is very quite; you won't hear it at all unless you are in a silent room. Focus is generally quick and sharp. Sometimes it fails to focus; a little bit more often than I have noticed with other auto-focus cameras. Seems to happen most when focusing on featureless surfaces. The lens can be manually focused without moving the switch into the manual position. This feature is really easy to use when needed for a quick adjustment before releasing the shutter.

The lens feels very durable and the zoom is not going to creep on you. It is not light but not too heavy either; constant f/2.8 and high quality optics probably drive the weight. No buyer's remorse with this lens!

Comments about Pentax 16-50mm f/2.8 ED AL[IF]SDM Wide Angle Zoom Lens:

This lens has three great applications: as a general-use documentary lens for those who don't mind being close to the action, for landscape photography, and for those who will be filming HD video on Pentax's K7.

The focus is extremely fast, the action is smooth and the lens is light enough to carry around for a day. Like other lenses in this category—Canon's 24-70mm f/2.8L, for instance—the front of the lens moves in and out during zooming, and the zoom ring can be difficult to twist if the lens is pointing up. Gravity works against it, and there is a lot of glass in there. The zoom ring is also located pretty close to the camera body, and with the K7's D-BG4 grip attached, it can be hard for people with big hands to find that ring.

But when using the lens for video, the user sees an extremely bright image on the LCD, with excellent depth-of-field characteristic of wide-angle lenses, and very smooth focusing. The camera also recognizes faces when used in video mode, which helps assure there is correct focus even at f/2.8.