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07-25-2012, 11:06 AM   #16
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QuoteOriginally posted by 123jippo Quote
i hate my sigma 30mm cos its AF is not good and i do not recomend that lens for anybody
I own the Sigma 30mm f/1.4 and I think it is a terrific lens for the money. Color rendition is a little yellowish compared to current Pentax lenses but sharpness is terrific. I have never had any issues with the AF and if there were any I'd say the issue would be more camera related than with the lens, or more likely the problem lies behind the viewfinder.
Here's a quick snapshot wide open at f/1.4 handheld with the K-5 at a recent local Pentax outing. No complaints.



07-25-2012, 11:11 AM   #17
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QuoteOriginally posted by creampuff Quote
I own the Sigma 30mm f/1.4 and I think it is a terrific lens for the money. Color rendition is a little yellowish compared to current Pentax lenses but sharpness is terrific. I have never had any issues with the AF and if there were any I'd say the issue would be more camera related than with the lens, or more likely the problem lies behind the viewfinder.
Here's a quick snapshot wide open at f/1.4 handheld with the K-5 at a recent local Pentax outing. No complaints.
Did you adjust the colors to reduce the yellow in that picture? The shirt looks a bit bluish.
07-25-2012, 11:18 AM   #18
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QuoteOriginally posted by Docrwm Quote
Did you adjust the colors to reduce the yellow in that picture? The shirt looks a bit bluish.
The shot was taken early in the morning, with natural morning sunlight. As to the shirt color being bluish, subject was in the shade so color temperature would have been cooler, should be pretty obvious isn't it.
07-25-2012, 01:43 PM   #19
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QuoteOriginally posted by creampuff Quote
The shot was taken early in the morning, with natural morning sunlight. As to the shirt color being bluish, subject was in the shade so color temperature would have been cooler, should be pretty obvious isn't it.
No, it could have been taken at a different time and adjustment due to the yellow tint of the lens could have resulted in it. Just trying to understand the nature of that lens because I do not own a Sigma and am not familiar with their rendering.

07-25-2012, 06:24 PM   #20
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Original Poster
Thank you all for your advices. I see from photos in Flickr that 21mm/F3.2 has
more barrel distortion than 15mm/F4 or 10-20mm/F4. Is it because of ED element
in the last lenses ? It is important since I will use the lens for architecture photography.
I don't want the edge of building look like a curve.

Regards,
Purwoadi
07-25-2012, 08:35 PM   #21
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I'm no fan of the sigma 30mm f/1.4 but not everyone has the money or the stomach to spend so much on a lens. But as an owner of the FA31 I can say for landscape there are very few lenses that I would recommend as highly as the FA31 for Pentax cameras. I prefer the 47mm FOV and bokeh the FA31 gives me - It reminds me of the 80mm lenses I used on my Hasselblad 6X6. I find the FA31 does near-far compositions extremely well, even though distant subjects on the horizon may be slightly out of focus - the way the FA31 renders them only makes them look slightly less sharp.



Pentax K-7 SMCP-FA 31mm f/1.8 ASPH Limited - 1" ISO100 @ f/11


Pentax K-7 SMCP-FA 31mm f/1.8 ASPH Limited 15" ISO100 @ f/16

Last edited by Digitalis; 07-25-2012 at 08:45 PM.
07-25-2012, 11:15 PM   #22
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If somebody doesn't likes his sigma 30 1.4, I give perfect FA 35 2.0 for a sigma 30 1.4!
07-26-2012, 07:15 AM   #23
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QuoteOriginally posted by 123jippo Quote
My Sigma 30mm copy colors are good enough for me. Its little soft from near corners with big apetures but thats ok and understandable. But AF is not turstable at all and it makes pics keeper rate really very low but when focus is ok pics are nice. I have been using my sigma 30mm with K100D and K5 bodies and bo0th have same problem especially in low light. Maybe ur copy of this lens is better...
Here's a landscape shot from the Sigma 30mm at F/2, in camera HDR, Pentax K-x. I found the lens very usable when stopped down to F/1.8 or F/2.0. If you need to use it wide open, there's usually there's not enough light to auto focus, and the corners are pretty soft wide open.



Here's a hand held shot at 30mm F/2, ISO1600, 1/15th of a second. The bokeh is ok, except for in the edges where you get the triangular bokeh effect, with point light sources (xmas lights).



Last edited by sheld; 07-26-2012 at 07:30 AM.
07-26-2012, 07:28 AM   #24
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QuoteOriginally posted by sheld Quote
Here's a landscape shot from the Sigma 30mm at F/2, in camera HDR, Pentax K-x. I found the lens very usable when stopped down to F/1.8 or F/2.0. If you need to use it wide open, there's usually there's not enough light to auto focus, and the corners are pretty soft wide open.
Yes in very low light AF seems to work but focus mostly is uncorrect. I have tried to solve this problem taking many pics and reseting focus to other target between pics so mostly some pics are fine then. Lens is ok but focusing can not trust too much...in my copy I mean...

I also have found it good lens for HDR. I use it normally for HDR around f4 and manual focus.

QuoteOriginally posted by sheld Quote
Here's a hand held shot at 30mm F/2, ISO1600, 1/15th of a second. The bokeh is good, except for in the edges where you get the triangular bokeh effect.
I can get even sharper pics with my sigma when focus is correct
07-26-2012, 07:34 AM   #25
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QuoteOriginally posted by simbon4o Quote
If somebody doesn't likes his sigma 30 1.4, I give perfect FA 35 2.0 for a sigma 30 1.4!
That would be an interesting trade. The FA 35 is doubtless sharper across the frame than the Sigma, but I wouldn't do it. I love my Sigma too much as a short portrait lens. It's contrasty, tack sharp in the center, and has excellent oof rendering (for my tastes). Here's one at f/1.4. For phase-detect autofocus, you need to use the center AF point, and the field curvature makes it difficult to focus and recompose.





Here's a landscape example at f/5.6.


07-26-2012, 10:19 AM   #26
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QuoteOriginally posted by sheld Quote
Here's a landscape shot from the Sigma 30mm at F/2, in camera HDR, Pentax K-x. I found the lens very usable when stopped down to F/1.8 or F/2.0. If you need to use it wide open, there's usually there's not enough light to auto focus, and the corners are pretty soft wide open.



Here's a hand held shot at 30mm F/2, ISO1600, 1/15th of a second. The bokeh is ok, except for in the edges where you get the triangular bokeh effect, with point light sources (xmas lights).
The Sigma AF is fine in good light, but my K5/30mm f1.4 combo struggles in low light conditions (EV0 and below) As my next fastest AF lens is f2.4 I don't know of this is just a problem with the Sigma. Manual focus is fine. The 30mm aeems to front focus horribly in mixed low light conditions. It is fine in normal light 9with a bit of microfocus adjust)
07-26-2012, 10:49 AM   #27
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QuoteOriginally posted by Designosophy Quote
That would be an interesting trade. The FA 35 is doubtless sharper across the frame than the Sigma, but I wouldn't do it. I love my Sigma too much as a short portrait lens. It's contrasty, tack sharp in the center, and has excellent oof rendering (for my tastes). Here's one at f/1.4. For phase-detect autofocus, you need to use the center AF point, and the field curvature makes it difficult to focus and recompose.
The curved focus plane made me search for the pentax FA 35 2.0 after I have tested the sigma, but it is a big disappointment when you want to separate the focused object from the background. So now I'm trying to find sigma owner who is looking for sharpness across the field . So the sigma is the better "normal" lens for bokeh, sharpness in the center wide open, defocus. The FA 35 2.0(and DA 35 2.4 which is the same lens) is "normal lens" only because it is 35mm and sharp.
07-26-2012, 10:54 AM   #28
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QuoteOriginally posted by simbon4o Quote
The curved focus plane made me search for the pentax FA 35 2.0 after I have tested the sigma, but it is a big disappointment when you want to separate the focused object from the background. So now I'm trying to find sigma owner who is looking for sharpness across the field . So the sigma is the better "normal" lens for bokeh, sharpness in the center wide open, defocus. The FA 35 2.0(and DA 35 2.4 which is the same lens) is "normal lens" only because it is 35mm and sharp.
I don't have the FA35/2.0 -- I would assume it would do ok with background bokeh. The Pentax 70mm/2.4 is ideal for separating the focused object from the background, but its not a normal lens, its a telephoto. I have the Sigma 30mm, and it works good to defocus the background, but its not in the same league as the 70mm F/2.4. Maybe the new 50mm F/1.8 will work wide open too.
- Sheldon
07-26-2012, 11:13 AM   #29
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I'm not quite sure why people are saying the 30/1.4 is soft in the corners unless stopped down - of course it is, who on earth uses a f1.4 for across the frame sharpness !

Some examples : f1.4, f5.6 and f1.6 :





07-26-2012, 11:16 AM   #30
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QuoteOriginally posted by Frogfish Quote
I'm not quite sure why people are saying the 30/1.4 is soft in the corners unless stopped down - of course it is, who on earth uses a f1.4 for across the frame sharpness !

Some examples : f1.4, f5.6 and f1.6 :
I like #1, and that is one of the big advantages of f < 2.0!
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