Sigma 30mm f/1.4
Sharpness
© 2007 KenRockwell.com
Sigma 30mm f/1.4.
I got this one here. You also can get it here. It helps me keep adding to this site when you get yours from those links, too.
June 2007
back to: Top Specs Performance Recommendations
The Sigma 30mm f/1.4 is for hand-held shooting in dim light. For this it's sharper than you'll ever be able to use, since the depth of field at f/1.4 is so narrow.
Anything worth shooting at f/1.4 will be three-dimensional, and for that, perfect focus and absolute sharpness don't matter. Bokeh, the look of out-of-focus areas, is more important since most of the picture at f/1.4 is out of focus.
The biggest limitation to sharp images of flat objects at f/1.4 is getting perfect focus. I've been working at trying to get sharp images at f/1.4 for over 30 years, and I'm still working on it. It's very difficult.
This Sigma lens is worse than others for getting accurate focus on my Nikons at f/1.4. It took practice to learn its errors and correct for them manually. Luckily the focus offsets were consistent, making it easy to correct for them by deliberately focusing on something other than the subject, or using the focus scale manually. It was OK on my D40, but awful on my D200. Awful means obvious if you're looking for it, but not important for most real photography.
Here is what happens on my D200:
Guide Image, D200. Crops below are from a 100% image, either center of left side.
Here's what happens on my D200 if I don't play with the focus carefully:
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Autofocus, D200. It focused on something closer than the intended subject. |
AF locked on something at infinity. |
Sigma 30mm f/1.4 at f/1.4
This isn't a lens for shooting test charts. For that, get a macro lens.
I'd use this 30mm f/1.4 in dim light, but put my usual lens back on in good light. The Sigma 30mm f/1.4 is soft in the corners, even stopped down, if you're looking for it. Shooting this lens the way it is intended I never saw this. This Sigma is softer than my Nikon 18-200mm VR when stopped down, especially in the corners.
Don't use this lens for astronomy. Its optics aren't up to it, and there is no infinity focus stop. I'd use a Nikon 50mm f/1.4, especially manual focus, for astronomy. The best ultra-speed lens I've used at f/1.2 is the incredible Canon 85mm f/1.2L.
The rest of these examples, in order to make the Sigma look competitive, were made manually focusing the Sigma lens for best results, while all the other lenses were left in autofocus. The other lenses focused properly on my D200 while the Sigma didn't. The Sigma worked fine on my D40.
As a free feature, you can click any of the images to get to my review of that lens.
f/1.4
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f/2
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f/2.8
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Center
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f/4
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Center
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f/8
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Center
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Left Side
Sharpness Summary
This Sigma 30mm f/1.4 lens is great for hand-held shooting in the dark, especially with a little practice to get perfect focus for more critical things. For daylight use, my 18-55mm kit lens is sharper.
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Thanks!
Ken.