If you are considering buying this lens dont hesitate, highly recommended.

Purchased this lens to replace a 70-200 f2.8 which I found to be heavy and difficult to handle. I use a K5 camera with grip, this lens is just perfect, balances beautifully with this camera and the 50-135 focal length is so much more useful than the previous lens.

Pentax 50-135mm f/2.8 ED AL IF SDM SMC DA* review by Waratah

Helluva lens. From f3.5 and up has never let me down. Early I tried the 2.8 in unsuitable situation (hasty glamour shoots in nature etc) and was frequently underwhelmed but now I understand it better - its just brilliant.

Quality; handling; weather resistance; quick shift

SDM (always in the back of my mind)

I bought this lens to travel in Asia where the weather is Humid and rain.. SO far I tested the lens in Sichuan province in the forest to shot panda: Rain and humidity did not affect at all the camera and the lense (the big lens hood in the end turn out to be a really good protection for the lens...

Sharpness; Colour rendition; Quality

Lens hood far to big

Excellent Lens

Excellent lens, I haven't taken it off the camera since I got it. With the Pentax K5 its just brilliant.

I literally said - Wow

Bought this lens with some trepidation because of concern over SDM failures. I "needed" a lens in this range and 3rd party lens makers really didn't have what I wanted. There were reports that the SDM was remodeled in 2012 (hope that was true and not industry talk) because of the failures in both...