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Old Nov 29, 2010, 2:27 PM   #1
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Default Sigma's 30mm, 28mm, 34mm, or the 20mm?

EDIT: Sigma's 30mm, 28mm, 24mm, or the 20mm?


I have a Pentax K-r. I already have the pentax 50mm f1.4 among other lens's. I love it so much that i would like to buy another prime to compliment it. I was thinking in the price range of $300-$500. I am a big fan of sigma.

These are the lens's i have narrowed down to (based on nothing but the mm, and the max f stop) :

Sigma 30mm f/1.4 EX DC HSM
Lens
http://www.amazon.com/Sigma-Pentax-S.../dp/B000FG6CME

Sigma 28mm f/1.8 EX DG Aspherical Macro Large Aperture Wide Angle Lens
http://www.amazon.com/Sigma-Aspheric...pd_sim_sbs_p_1

Sigma 24mm f/1.8 EX DG Aspherical Macro Large Aperture Wide Angle Lens
http://www.amazon.com/Sigma-Aspheric...pd_sim_sbs_p_2

Sigma 20mm f/1.8 EX DG RF Aspherical Wide Angle Lens
http://www.amazon.com/Sigma-Aspheric.../dp/B00005RKSN


I dont really know anything about these... i do know the 30mm seems to be the most popular. I want a wide angle lens, but for nothing in particular, i just feel that sometimes the 50mm has a too small of a field of view for interior shots at family gatherings and such.

I am afraid that the 30mm wont be too different than the 50mm that i already have, but i am afraid that the 20mm would be distorted... I dont really know.

Any help you could offer me would be awesome!




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Old Nov 29, 2010, 4:30 PM   #2
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unless the 20mm is designed for full frame cameras there is very little chance of there being signiicant distortion - specially in a prime lens where it can be very carefully designed
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Old Nov 29, 2010, 5:15 PM   #3
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i have a stupid question. if i put my sigma 18-250 on my pentax, and go to 20mm, will that be the same field of view as the 20mm prime (and at 30mm will it be the same as the 30mm prime etc...)?
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Old Nov 29, 2010, 9:51 PM   #4
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Quote:
Originally Posted by ewheeler20 View Post
i have a stupid question. if i put my sigma 18-250 on my pentax, and go to 20mm, will that be the same field of view as the 20mm prime (and at 30mm will it be the same as the 30mm prime etc...)?
Yes...20mm is 20mm (assuming we aren't comparing different cameras with different sized sensors). The difference will be in optical quality. A zoom will tend to have more distortion than a prime and may not be as sharp, although at normal print sizes or regular computer/web viewing the lack of sharpness may not be noticeable.
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Old Nov 30, 2010, 11:18 AM   #5
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Thanks rj.

ok, I'm stuck between the 30mm 1.4 and the 24mm 1.8.

Does anyone know which one is sharper? the price difference is $10.

the 30mm is a f1.4 EX DC lens.
the 24mm is a f1.8 EX DG Aspherical Macro lens.

What is the difference between DC and DG? my camera is the pentax K-r (if that matters)
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Old Nov 30, 2010, 12:01 PM   #6
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I think I'd go with the 30mm, as sharpness towards the center of the frame is very good, even wide open (whereas most lenses need to be stopped down a bit). I personally wouldn't care about the corners for people type photos, which I'm more likely to be taking with the aperture wide open), and it's a brighter lens compared to the 24mm (which means you could stop it down some for sharper photos compared to the dimmer 24mm f/1.8).
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Old Nov 30, 2010, 12:23 PM   #7
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thanks! 30mm it is. I'll have it by tomorrow.
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