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10-10-2014, 02:38 PM   #1
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Photozone fans, which is better.

Given the two lens graphs , which lens would you pick for your K-3?



10-10-2014, 02:55 PM   #2
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QuoteOriginally posted by normhead Quote
Given the two lens graphs , which lens would you pick for your K-3?
the blue one
10-10-2014, 03:04 PM   #3
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Um... lack of info. Is that measuring sharpness, CA, or ?
Are the scales the same - does the tick marker on one line up with the other? For all we know the left side of the right hand chart could be higher than the best point on the left chart.
10-10-2014, 03:05 PM   #4
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Blue? Where is that?

10-10-2014, 03:09 PM   #5
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Ha ha, a bunch of smart people... the scales are deleted for a purpose...but no the scales ar not the same... the graphs start at the same ƒ-stop, if one has more than the other, it's because that's what was published.
10-10-2014, 03:11 PM   #6
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The right one is probably a faster speed lens, f1.4 or so and therefore less sharp in the corners wide open. That is probably my choice.
10-10-2014, 03:11 PM   #7
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Yeah, missing the scale... and more infos are needed in general... Are these two graphs created with the same camera/sensor?
10-10-2014, 03:29 PM   #8
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If that was all the data one had, it would not be an informed decision. Are the graphs directly comparable? The scales are different. What is the measured LW/PH? What is the aperture? The graph the left includes the extreme border, the one on the right does not. What sensor or sensors are the based on?


However, both graphs are tests of the Pentax SMC-FA 31mm f/1.8 Limited. The graph on the left is the 16 MP (K5) sensor, and the one on the right is the 10 MP (K10D) sensor. Both say it is a good lens (which is pretty much the received wisdom on that particular piece of glass) and it should be equally good on the 24MP k3 sensor.


What the graphs do say, however, is that each sensor (and the in-camera processor) has its own attributes and absolute comparisons between systems are not useful. The most that can be said about lens A on sensor X if that if it is good, bad or indifferent, it is likely to be roughly similar on sensor Y.

10-10-2014, 03:29 PM   #9
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Pretty pointless without the scale and knowing the sensor size/camera.

Last edited by Winder; 10-10-2014 at 04:06 PM.
10-10-2014, 03:32 PM   #10
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Clever, Norm. I will happily take the lens!

edit: meh, PJ1 spoiled the fun
10-10-2014, 03:47 PM   #11
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The graph on the right has 5 divisions shown, the one on the left has 4 divisions shown. We can estimate that the peak sharpness on the left is ~4.5 divisions, while on the right, it goes to 5. If we assume the divisions are the same relative meaning, the one on the right is sharper. If we assume the top of the chart is the same for both, then the one on the left is sharper. If Nigel Tufnel made the graphs, they'd go to 11, and this wouldn't be a problem.
10-10-2014, 03:48 PM   #12
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The graph on the right looks sharper..........
10-10-2014, 04:28 PM   #13
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I guess it depends on whether higher bars indicate something good or something bad...
10-10-2014, 04:37 PM   #14
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QuoteOriginally posted by PJ1 Quote
However, both graphs are tests of the Pentax SMC-FA 31mm f/1.8 Limited.
Based on this response and the information presented in the Photozone graphs I have all the information I need so I acquired a MIJ FA31 today.

Isn't that how this all works?
10-10-2014, 05:10 PM   #15
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QuoteOriginally posted by monochrome Quote
Based on this response and the information presented in the Photozone graphs I have all the information I need so I acquired a MIJ FA31 today.
I bet that FA31 would perform wonderfully on a K-S1.
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