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01-10-2010, 09:40 PM   #1
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Join Date: Apr 2009
Location: New York City
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Posts: 33
Pentax A 300mm/f4 Lens

I am thinking about picking this lens up. Does anyone have it and a K20D? I want to use it and a tele-converter Pentax 1.7x AF converter. If I can find one used. A 1.4 or 2.0 sigma if not. My thinking is that I might get a better use out of this setup then a 150-500mm sigma. For a few hundred dollars less then the BigMos. The 1.7x or the 1.4, 2.0 will cost me more then the Pentax A * 300mm/f4.

So these are my questions.

How is the resolution on the lens on a k20d without a TC compared to other 300mm lenses?

Anyone have the lens and a 1.7 or a sigma 1.4 2.0? If so how sharp is it on a tripod?
I cannot find if the lens is compatible or not with the sigmas. It would be a waste if I got then lens and a sigma TC and they could not be used together.

01-10-2010, 11:10 PM   #2

Join Date: Oct 2006
Location: Chicago suburb, IL, USA
Posts: 1,535
Hi Xcom,

I no longer own this lens, but it's excellent. It's small and light (about as compact a lens as you'll find at this spec), sharp wide open, and the build quality is top shelf.

The only two faults I can think of are the relatively long minimum focus distance (@13ft) and possible CA/PF in high contrast situations at wide apertures.

It mates well with the P F 1.7x AFA, and because of the recessed rear lens element, the Sigma TCs can be used with it (but with these, it will remain a manual focus lens, of course).


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1.7x, k-mount, k20d, lens, pentax, pentax lens, sigma, slr lens, tc
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