Top quality WR standard zoom

After reading many good reviews on this lens, I decided to give it a try. It is a replacement for a Pentax 18-135 which I used primarily in bad weather. My regular go to lens is a Tamron 17-50.

The lens arrived just at the peak of the fall season. Perfect timing. I was too eager to try it even before I had a chance to check for AF accuracy. I was initially a little disappointed because it was not sharp enough. It turned out it requires a -4 on my K-S2. After this adjustment, it is tack sharp across the entire frame every time. Center sharpness is excellent even wide open at all focal length, neither the Tamron 17-50 nor the 18-135 can do that. Edge sharpness improves on stopping down. I must point out that edge and corner sharpness is significantly better than the Tamron 17-50. I have no reservation as far as IQ is concerned. In fact, I am starting to look for a fast standard zoom to replace the Tamron 17-50. I do have fixed lenses to cover this range, but I honestly prefer the convenience of a zoom.

AF is fast and silent. It is faster than the 18-135. Build is solid. It is, however, big, much bigger than either the 18-135 or the Tamron 17-50. It is not cheap, but well worth the cost.

Can it be even better? If Pentax will make a f/2.8 - 4.0 or a constant f/4.0. This is the reason for taking 1/2 star off.

Twong wrote:

Can it be even better? If Pentax will make a f/2.8 - 4.0 or a constant f/4.0. This is the reason for taking 1/2 star off.

If Pentax make it a constant f/4 they would probably add a star (DA*) .

Fine review, and very much in line with what others have experienced.

I'd consider this lens as potentially replacing my various zooms, but weight, size and lack of constant aperture are also factors for me. No major concerns regarding image quality and build, though.

I had the same experience with this lens.  Maybe it is a fairly universal problem.  Initially I was very disappointed - especially with portraits where I used a wide opn aperature - but dug out the manual to read up on the micro adjustments. Makes you wonder how come Pentax does not just do it right in the first place. Just like you, I used to use the Tamron F/2.8 as my everyday lens and I still carry it because the wide aperture is handy in low light situations and nice for portraits but other than that you will find the lens mostly on my K30 is the 16-85 Pentax.  That extra reach is just so handy when on holidays and the lens is now sharp.  This shot was taken at ISO 200 and 1/60 of a second while panning the pilot boat.

NickTent wrote:

Hi,

I just purchased the same lens and I have the same camera, pentax k-s2. I don't understand what a -4 adjustment is. Can you please explain?

Thanks,

Nick

That's a value for auto focus fine adjustment. Some lenses back focus or front focus and this adjustment allows you to correct that. You can find that in the Custom Setting Menu. Its #26 on my K5IIs. Not sure if that would be the same for the KS2.

Totally agree - top lens.