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02-17-2011, 12:20 PM   #1
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sigma 28mm F1.8 EX DG ASP Macro

Hello,

I have a K-x. I need an fixed wide-angle prime, standard prime for portrait foto in low light. Sigma 28mm f1.8 macro it's cheaper than SMC PENTAX FA 31MM F1.8 LIMITED. But sigma 28mm f1.8 macro works with auto focus AF from the camera body?

How about the sigma 30mm F1.4 EX DC lenses because it dont have hsm for pentax and is J AF mount. It Will work with the k-x without any adapter and the auto focus?

Thanks

02-17-2011, 12:29 PM   #2
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Correct- full auto usage and no adapter needed. Check it's reviews in our third party lens review database, accessible via the "lenses" button above.

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02-17-2011, 12:35 PM   #3
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both lenses: sigma 28mm f1.8 asp macro and sigma 30mm f1.4 ex dc are working with AF of my K-X? What other lens will recomend for potrait in low light with focal length lower than 50mm? Thanks
02-17-2011, 02:06 PM   #4
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Yes, both those lenses will work perfectly with your K-x without any adapters, etc. The other lens you might consider is the new Pentax DA 35mm f/2.4 it is a very good lens (from what I hear) and is also priced nice.

02-17-2011, 03:03 PM   #5
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I'm happy with old Pentax FA24 and FA35 lenses in this category. Sigma 28/1.8 is extremely heavy, comparable weigth to you camera. I used Sigma 24/1.8 in EF mount and it was good besides the problem with focus accuracy and the bulk.
02-17-2011, 06:17 PM   #6
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I haven't used the new DA 35 and I'm biased because I own the Sigma 28mm F1.8 EX DG ASP Macro - so I recommend the Sigma. Not only it is faster in aperture but it also focuses much closer (18cm).
But as a K-x user, the DA 35 would probably be the better choice for you (considering price and size).
And yes, any Auto Focus lens will work on a Pentax naturally without any adapters or so.
02-21-2011, 10:32 AM   #7
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For this lens: Sigma 28mm F1.8 EX DG ASP Macro i need to know if Aperture can be set auto by the camera body K-x. This lens has Aperture ring but it dont has A position.

Thank you
02-21-2011, 10:55 AM   #8
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And have you physically seen the lens, or do you judge by picture in web-shop? That picture may be misleading, it could be F mount shown.
Actually I'm not sure if the DG version Sigma has any aperture ring in K-mount. But DG means digital friendly and it must work with digital. But be prepared that it may not be compatible with non-digital Pentax cameras (I experienced such problem in combination of Sigma 180mm and Pentax SuperA). Sigma is reverse-engineering the connection and does not implement whole protocol.

02-21-2011, 12:12 PM   #9
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The K mount version has an aperture ring. I own the lens. All of my EX DG lenses have an aperture ring.

QuoteOriginally posted by elho_cid Quote
And have you physically seen the lens, or do you judge by picture in web-shop? That picture may be misleading, it could be F mount shown.
Actually I'm not sure if the DG version Sigma has any aperture ring in K-mount. But DG means digital friendly and it must work with digital. But be prepared that it may not be compatible with non-digital Pentax cameras (I experienced such problem in combination of Sigma 180mm and Pentax SuperA). Sigma is reverse-engineering the connection and does not implement whole protocol.
02-21-2011, 12:34 PM   #10
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You have pretty good collection of Sigmas Stephen! Is the 28/1,8 in the same league as 180mm macro IQ wise?
02-21-2011, 01:10 PM - 1 Like   #11
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They both excellent in my opinion. I don't use the 180mm as much as I should though. Here are some links:

Sigma 28
Stephen Merola's Photos : Photo Keywords : sigma ex dg 28mm f

Sigma 180
Stephen Merola's Photos : Photo Keywords : sigma ex dg 180mm f
02-21-2011, 01:30 PM   #12
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I'm not sure if that's really the case but I'd say every lens prior to HSM has an aperture ring (with A position!).
I can't compare it to the 180 macro since I don't own it but I can say that it perform very decent. Stopped down to f/4 there is nothing left to criticize. Damn sharp and moreover one of the lenses with the nicest bokeh I own. Nearly as good as the 50's!
02-21-2011, 01:42 PM   #13
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who has better optical performance: sigma 28mm f1.8 Ex Dg Asp macro or sigma 30mm F1.4 EX DC HSM? Contrast, Bokeh, sharpness?
02-21-2011, 03:06 PM   #14
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Try to find some reviews (for example on this very site) to get neutral opinions.

I would say what the general consenus does -
They won't differ that much on bokeh - but the newer Sigma 30mm F1.4 may be a little better on this one.
The 30mm is designed as a normal lens for APS-C so it will most likely outperform the 28mm lens which is designed as a wide angl lens for full frame.
But as I said before: the 28mm Macro does a mighty fine job in the bokeh compartment.
It is only beaten by the longer and faster Sigma 50mm F1.4.

On sharpness the 30mm loses in the end - center sharpness is very high even at f/1.4 but the borders are quite soft and never get on the 28's level. I also guess filed curvature will ge higher for the 30 F1.4.

In short:
Contrast? Even.
Bokeh? 30mm F1.4
Sharpness? 28mm F1.8 Macro

Depends on your needs in the end.
I would choose the 28mm F1.8 over the 30mm F1.4 every time!
02-21-2011, 06:16 PM   #15
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And the 28 has great macro performance.

QuoteOriginally posted by Egg Salad Quote
Try to find some reviews (for example on this very site) to get neutral opinions.

I would say what the general consenus does -
They won't differ that much on bokeh - but the newer Sigma 30mm F1.4 may be a little better on this one.
The 30mm is designed as a normal lens for APS-C so it will most likely outperform the 28mm lens which is designed as a wide angl lens for full frame.
But as I said before: the 28mm Macro does a mighty fine job in the bokeh compartment.
It is only beaten by the longer and faster Sigma 50mm F1.4.

On sharpness the 30mm loses in the end - center sharpness is very high even at f/1.4 but the borders are quite soft and never get on the 28's level. I also guess filed curvature will ge higher for the 30 F1.4.

In short:
Contrast? Even.
Bokeh? 30mm F1.4
Sharpness? 28mm F1.8 Macro

Depends on your needs in the end.
I would choose the 28mm F1.8 over the 30mm F1.4 every time!
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