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01-30-2014, 10:55 AM   #1
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DxO Mark data for lenses on the K-5 II and K-5 IIs

DxO Mark has just released their data for lenses on the K-5 II and K-5 IIs :

Best lenses for the 16-MPix Pentax K-5 II and K-5 IIs: Measurement data now available online - DxOMark

What's interesting is that the increase in Perceptual Megapixels (P-Mpix), ( explained here Looking for new photo gear? DxOMark's Perceptual Megapixel can help you! - DxOMark ) is substantial between the K-5 II and the K-5 IIs http://www.dxomark.com/Reviews/Best-lenses-for-the-16-MPix-Pentax-K-5-II-and-K-5-IIs-Measurement-data-now-available-online/Sharpness-comparison-between-Pentax-K-5-IIs-and-K-5-II

However the increase in P-Mpix between he K-5 IIs and the K-3 is much more modest, except with truly exceptional lenses, such as the Sigma 35mm F1.4 DG HSM A
Sharpness comparison between Pentax K-5 IIs and Pentax K-3 - DxOMark

It confirms the fact that very high pixel density sensors such as the one in the K-3 are extremely demanding and require more than "merely good" lenses.

01-30-2014, 11:08 AM   #2
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QuoteOriginally posted by Matchete Quote
DxO Mark has just released their data for lenses on the K-5 II and K-5 IIs.
More DxO numerological fantasy boll*cks. All such numbers are meaningless unless you quote some confidence limits. Which they don't.
01-30-2014, 11:18 AM   #3
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QuoteOriginally posted by kh1234567890 Quote
More DxO numerological fantasy boll*cks. All such numbers are meaningless unless you quote some confidence limits. Which they don't.
I agree that their tests are heavily dependent on lens sample variation, which may explain some strange results such as the DA 55-300 having been deemed sharper than the DA*300.

However their methodology is clear, and their tools much more advanced than those used for usual sharpness tests.

I've conducted comparisons between my now sold K-5 and my K-5 IIs, and the difference in sharpness is obvious with good lenses, which backs their claims.
01-30-2014, 11:33 AM - 1 Like   #4
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QuoteQuote:
It confirms the fact that very high pixel density sensors such as the one in the K-3 are extremely demanding and require more than "merely good" lenses.
I have no idea what Megapixel is in an image... what does it measure?

Using test charts Imaging Resources comparing a D7000 to a D7100 shows about a 15% to 20% increase in resolution, and they show me the test charts to do my own evaluation. I have no idea what the heck DxO is talking about.

QuoteQuote:
DxOMark Score
DxOMark Score corresponds to an optimal focal length/aperture combination. The score corresponds to the quantity of information that can be captured by the camera. Each focal length/aperture combination provides a numerical value. The highest value is the DxOMark Score.
DxOMark Score is measured for low-light conditions: 150 lux and 1/60s exposure time. Such conditions correspond to a correctly-lit living room (with no daylight): it is a difficult but rather typical photographic use case.
OH please, DxO mark scores are predicated on poor lighting conditions.Useless to most people most of the time, I completely understand them now... what kind of company basis their whole analysis, on people shooting with ambient lights in their living rooms? That is probably one of the most useless rationales I have ever seen, and explains why their ratings so heavily favour lenses in larger formats.

Instead of showing you what the cameras do under ideal circumstances, they rate them on what they do in the worst circumstances, circumstances that many of us would never expect good results from.

I don't know how else to say it, these people are frauds.


Last edited by normhead; 01-30-2014 at 11:43 AM.
01-30-2014, 01:01 PM   #5
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QuoteOriginally posted by normhead Quote
I have no idea what Megapixel is in an image... what does it measure?

Using test charts Imaging Resources comparing a D7000 to a D7100 shows about a 15% to 20% increase in resolution, and they show me the test charts to do my own evaluation. I have no idea what the heck DxO is talking about.

OH please, DxO mark scores are predicated on poor lighting conditions.Useless to most people most of the time, I completely understand them now... what kind of company basis their whole analysis, on people shooting with ambient lights in their living rooms? That is probably one of the most useless rationales I have ever seen, and explains why their ratings so heavily favour lenses in larger formats.

Instead of showing you what the cameras do under ideal circumstances, they rate them on what they do in the worst circumstances, circumstances that many of us would never expect good results from.

I don't know how else to say it, these people are frauds.
I was only referring to the Sharpness (P-Mpix criteria), which isn't hard to grasp : Looking for new photo gear? DxOMark's Perceptual Megapixel can help you! - DxOMark

It is IMHO really helpful to help people select the sharpest lenses for their own camera (without taking into account bokeh, color rendering... of course).

I agree though that the aggregate score is really biased as it heavily favors large aperture lenses, which is one of the reasons why Full Frame lenses have higher ratings, but they also have higher sharpness ratings because of a lower pixel density which is a fact, not a wild guess from DxO.

Btw I am a huge Pentax fan and don't feel the need for Full Frame in case you wonder .
01-31-2014, 08:53 AM   #6
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Without wanting to dominate this thread, I created my own to explain why DxO data are extremely unreliable if not fraudulent. Their data only pertain to images shot "in a living room with no daylight", and are quite irrelevant when discussing lenses to be used in sunlight or partial sun, or even a living room with a window. I've provided images from Imaging Resources that demonstrate that when applied to images shot under commercial lighting, their confusions are erroneous. They apply only to the low light and restricted spectrum in which they were shot, and despite their weak justification for using this lighting, are only a very small step away from outright lying when it comes to 99% of the images posted on this site. If you shoot in good light, DxO ratings are of no use to you.

In your mom's basement, a Sigma 35mm 1.4 lens might produce the best image. But outdoor shooting at F 5.6 does the Sigma produce the best image? DxO's information won't tell you that. It will just tell that overall, shooting at every ƒ stop the Sigma will be better. For those of us who shoot as close to ƒ5.6 as possible to use the sharpest part of the lens, and usually in good light, their data is meaningless.

https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/249962-dxo-...ml#post2670061

Last edited by normhead; 01-31-2014 at 08:59 AM.
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