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01-28-2009, 12:23 PM   #1
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Pentax 16-45 f4 or Sigma 18-50 f2.8?


I currently have a Pentax DA 18-55 f3.5-5.6 AL II lens mated to my K20D and I am thinking of upgrading.

After some research, my choices seem to be between Pentax 16-45mm f4 (US$ 300.00) or Sigma 18-50 f2.8 (US$ 375) within my budget range.

If anyone out there has had experience with both of these lenses side-by-side on a K20D, or just opinions based on their expertise, I'd appreciate any suggestions. BTW, I also have a Pentax-DA 55-300mm F4-5.8 ED that I am fairly happy with so the long range, for now, seems covered.

Thanks much.

01-28-2009, 01:58 PM   #2
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Seriously, they really have little differences among them if you are shooting landscape with aperture f8.

However, the overall impact can differ from these lenses. Here is my subject untested gut feelings of mine towards these two zooms you put up.

Pentax 16-45

It has that sharp clinical look with cool tone to landscape images using f8. Its diffraction limit kicks in earlier than Da 14 f2.8: f11 versus f16

Stopping down, its overall rendering is similar to Da 14 f2.8 stopping down

It takes highlight poorly and it is prone to flare.

The bokeh from this lens at f4 is harsh and distracting. As long as you don't care about bokeh, this is a fine zoom.

Sigma 18-50 f2.8

Nothing wrong with this lens. Just the overall look is a bit dull. With pixel peeping, most of the parametres are there but the zoom lacks something for me. Yes, the extreme corner is soft at f2.8 but which zoom doesn't have this property?

Bulky build and heavy too. I prefer Tamron version

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