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08-18-2012, 02:08 PM   #1
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big aperture 50 - 55 mm lens for Pentax K-5

I am in the process of buying a big aperture 50 - 55 mm lens for use with a Pentax K-5 body. I would very much appreciate some advice. Could you please share your experience?

I have found two lenses that I can buy locally at approximately the same cost. They are Pentax SMC FA 50 / 1.4 ( ) and Sigma 50/1.4 DG HSM ( ).

I have found a number of reviews:

Pentax SMC FA 50 / 1.4

Sigma 50/1.4 DG HSM

Despite reading these reviews, I am still undecided what lens to buy. Can you please share your comments and advice? Also, are there other lenses that might be a better choice than these two?

Thank you in advance for your help.

08-18-2012, 04:05 PM   #2
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Do they cost less than the brand new Pentax DA 50mm f1.8? A little darker than the 1.4, though. Lens speed is like an addiction.
08-18-2012, 04:10 PM   #3
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I have the FA 50/1.4. I considered buying the Sigma. Differences are:

Sigma is definitely sharper, especially at wide apertures. The Pentax starts getting really sharp at f/2.2. The Pentax greatly benefits from a lens hood. You can get the Pentax dedicated collapsing rubber hood for $15 from B&H.

The Sigma is a lot larger, heavier, and more expensive. But it also has nicer build qualiy.

They both have nice smooth bokeh.

I chose the Pentax because I was mostly looking for a portrait lens. The Sigma is so sharp that it almost makes for unflattering portraits. The Pentax is sharp enough for nice picture quality without showing every pore & wrinkle.
08-19-2012, 04:36 AM   #4
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Thank you Na Horuk and msatlas for your answers.

The costs are: Pentax DA 50mm f1.8 is 25% cheaper than Pentax SMC FA 50/1.4. Sigma 50/1.4 DG HSM is only 2% more expensive than Pentax SMC FA 50/1.4.
My impression is that aperture and quality makes Pentax DA 50mm f1.8 less attractive to me.

In favour of Pentax SMC FA 10/1.4: less weight, smaller, some reported focus problems with Sigma 50/1.4 DG HSM.

In favour of Sigma 50/1.4 DG HSM: sharp, build quality.

I am a bit worried about the focus problems with Sigma that is reported in some of the reviews that I mentioned earlier. (Is there a real reason to be worried?)

08-19-2012, 05:58 AM   #5
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If there are focus problems with sigma 50 1.4 - they are correctable(and it's free in sigma service). The FA 50 1.4 is another thing it's focus problems come from it's performance wide open - soft, not sharp and low contrast - perfect combination for every camera to focus badly. And comparing the bokeh of the pentax with the one from the sigma is impossible, the sigma is much more smoother even from wide open.
But the FA 50 1.4 is nice lens for it's money on the second hand market!
My opinion - if you have the money - buy sigma, if not FA 50 1.4 is perfect. Next week there is going to be a review comparison between DA 55 1.4, DA 50 1.8 and FA 50 1.4 - wait and see about the DA 50 1.8 but I think the FA 50 1.4 will be better.
08-21-2012, 07:12 AM   #6
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I went through the same decision process and chose the Sigma. I have never looked back. Super sharp at f1.4 and through-out the aperture range. Heavy, but that says loads about the build quality. It is a super lens.
09-03-2012, 07:19 AM   #7
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Thank you all!
(I bought the Sigma 50/1.4 DG HSM.)

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