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05-30-2009, 02:34 PM   #16
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QuoteOriginally posted by cheve Quote
Your points on impact of sampling error, product variations and etc to our observation of the lens IQ is much appreciated. Unfortunately, I think it would be difficult to assemble a relatively large sample size(say n>25) from each version of 50/1.2 to run a suit of test and be able to express the result in certain degree of statistical confident level.
Even the more professional testers with some credibility ignore sample size. They test one lens. If they get odd results they consider testing a second. We just hope that manufacturers can mostly get things right.

As for your question, someone might have owned all three variations, rigorously tested them and reached conclusions based again on the sample size of one. But at least they know which of those three lenses is the best.

05-31-2009, 04:07 AM   #17
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05-31-2009, 09:06 PM   #18
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my observation comes from comparing multiple copies of the K an A series 50mm f/1.2 lenses I picked the one that showed the greatest sharpness...a I returned the rest to my collection. I test lenses on the Pentax LX with ilford PAN-F 50 and Kodak Tech-pan both exposed at Iso 25 - under a meticulous development regime and I compared the results under a high magnification precision schneider loupe.

here's a sample image at f/1.2, people often moan that the Pentax 50mm f/1.2 lenses aren't contrasty enough wide open. the Leica Noctilux f/1.0 isn't particularly contrasty lens wide open either niether, is the Voigtlander nokton 35mm f/1.2. that's the price you pay for extremities of lens design, but consider what the f/1.2 lens is for...low light, making images of usually high contrast scenes. You don't want to use a lens that has tons of contrast for scenes that are already too contrasy?

and a 100% crop - unsharpened.

these were shot hand held, 1/8 second @ISO1000 f/1.2

Last edited by Digitalis; 05-31-2009 at 09:23 PM.
05-31-2009, 09:13 PM   #19
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f/1.2 lenses are also great portrait lenses...they are especially deadly at candid work...

in regards to the Noct-Nikkor lenses which have established a cult status amongst the nikon community. They are good lenses...but they aren't THAT good in a similar fashion to the Leica Noctilux, they aren't that great when they are stopped down, they are better used at apertures of f/4 and wider. and the Pentax 50mm f/1.2 lenses aren't great wide open, but they are at least better than they are exceptional performers at apertures of f/4 and smaller I consider the pentax 50mm f/1.2 lenses to be the best "all rounder" lens I have used. And in some situations where it doesn't do a good job, I often come up short trying to think of a lens that would do substantially better.

Last edited by Digitalis; 06-01-2009 at 05:34 AM.
06-01-2009, 10:27 AM   #20
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Digitalis, thank you for the additional informations

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