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Old Oct 2, 2007, 2:52 AM   #11
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bilybianca wrote:
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The differences normally should be subtle and might depend on the individual lens. I did a test some time ago and my FA 1.4 was clearly sharper than my F 1.7, which wasn't good at all wide open. Stopped down a bit the difference was gone.

Kjell

Kjell

You did a very convincing test

http://forums.steves-digicams.com/fo...m_id=94&page=1

Daniel
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Old Oct 4, 2007, 1:16 AM   #12
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bilybianca wrote:
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The differences normally should be subtle and might depend on the individual lens. I did a test some time ago and my FA 1.4 was clearly sharper than my F 1.7, which wasn't good at all wide open. Stopped down a bit the difference was gone.

But can someone please explain to me why you should compare the two lenses wide open. IMO it is more relevant to compare them both at f1.7, and then consider the f1.4 as an extra bonus with the faster lens. Most people seem to se it the other way, but I've never understood why.

Kjell
I agree the test should be done not only at the widest but at all the stops from top to bottom. The sweet spot will probably be reflected in the difference between the two wide open. Quite often the best aperture will be at a higher f/stop on the slower lens and at a lower f/stop on the faster one! This usually will aid in lower light photos being slightly sharper with the faster lens as the sweet spot is at a lower aperture.

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Old Dec 3, 2007, 10:38 PM   #13
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1freek wrote:
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Is anyone using the Pentax SMC-A-50mm f1.7 (or the 1.4, for that matter) with a K10D? How do the two marry? Is it a good union?

Am hoping someone on this thread can pick me up and provide some insights.

Thanks in advance,


1freek
I am shocked by how well my SMC A 50mm 1.4 works with the Pentax K10D. I almost always use it in Av mode, and since it is the A lens, "automatic" the camera can adjust the aperature in the lens automatically. It is a little difficult to focus in low light in F1.4, but it works well and has a razor thin depth of field. I find the focus indicator is slightly off at times, especially in low light on objects without good contrast.

I did a quick test shooting my computer monitor with the lens, and also found F4.0 to be the sharpest in my unscientific test. At 1.4 the pictures are a little soft, but not terribly so if you achieve a good focus (but the depth of field is very thin). Sample picture attached. F1.4, 1/20, 400
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