Web Analytics RiceHigh's Pentax Blog: PhotoZone New Lens Test on the Q "01" Prime (with a New Resolution Rating System)

Tuesday, November 15, 2011

PhotoZone New Lens Test on the Q "01" Prime (with a New Resolution Rating System)

http://www.photozone.de/pentaxq/688-pentaxq85f19?start=1

Well, the distortion is really "extra-ordinary" for a prime! The diffraction comes into play for anything beyond f/4! (This was what I "predicted" long ago!) The most interesting thing on PZ part is that the LW/PH figures are not published anymore, as it is just about 70% as good as the micro-4/3 as briefly and vaguely told but yet it is still marked good to excellent in the "IQ" charts for "better" representation.. >:-[

At the same time, I'm afraid that the quality and reference value of the PZ lens test reports are also degenerating, with the introduction of such an "improved" less-embarrassing resolution rating system (to some manufacturers)! :-o Klaus, what do you think? (Of course, you do have some good reasons of your own to do so, don't you?)
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Klaus Schroiff's avatar - Go to profile

Klaus Schroiff · 695 weeks ago

There's no magic in the new rating scheme:
x = (a -600) / 1300 * 5
where "a" is the "old" LW/PH value. From a qualitative perspective NOTHING has changed at all. If we used LW/PH the charts would look EXACTLY the same.

The LW/PHs are really misleading. They are, for instance, heavily dependent on the RAW converter. The LW/PHs can vary by 30% just because of this parameter. Camera JPGs are for instance, also RAW-converter (in the camera) and much softer than RAWs converted with the "best" converters.
There's also no way to keep the RAW converter static. The output quality varies even on a simple version level (eg ACR3 vs ACR4 vs ACR5) - this is one of the reasons why we ALWAYS mention that the ratings are not cross-system comparable. Yet people concluded that e.g. Nikon is better than Canon just because the LW/PHs are higher (because the D7000 is capable of delivering sharper results than the EOS50D which is nothing to do with the lenses at all).

Technically it is meaningless whether to use LW/PH or the new ratings. There is simply no loss of information. We simply took away the misleading part.
9 replies · active 694 weeks ago
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Walt's avatar

Walt · 695 weeks ago

Resolution wise the "01" looks to be very impressive which should help the Q to generate decent shots dispite it's image quality challeged tiny sensor. However, I am trying to understand PZ's rating philosophy regarding M4/3 system lenses versus Q lenses. PZ has been critical of some of the M4/3 lenses due to bad distortion along with in camera correction and in fact did not give ratings due to these issues. Yet the Q prime "01" received a pretty good rating despite heavy distortion and I was under the impression that the Q also corrects distortion in camera. Is there an inconsitency between the two systems or has PZ changed it's view on this?
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Klaus · 695 weeks ago

The difference is that you can disable the auto-correction in the Q. This is next to impossible on MFT (you've to use non-mainstream RAW converters). The Q tests show the "native" performance of the lens so we also provide ratings here.
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Walt · 695 weeks ago

Got it, thanks Klaus. Good work too despite (ignore Rice High's comments :)).
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RiceHigh 110p · 695 weeks ago

It is *always* wise to ignore me *completely*! ;-D
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RiceHigh 110p · 695 weeks ago

But how can we compare the *absolute* resolution differences between cameras and systems when there is not a fixed reference line?
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Klaus · 695 weeks ago

Technically this is not possible. e.g. image sensors can have a different Bayer-pattern (or just take the Foveon approach). This alone will require different demosaicing algorithms to convert the RAWs (Foveon does not require any demosaicing). RAW converter A may be good for a system X but not for system Y and another RAW converter may have it the other way round.

In practical terms there's not a huge difference between the Bayer-algorithms so you could set a base line at date X and start testing across all systems with the same RAW converter (version) with an accuracy of -say- 90%. However, if a new system emerges you're stuck again. You have to use the new version of the RAW converter which is likely have different algorithms (as mentioned this happens with ACR all the time) so you base line went gaga.

In terms of lens testing even that would not work though simply because the different base cameras have different AA filter, different megapixels and different post-processing so a cross-system comparison is not valid. This is mentioned several times on PZ as a consequence. This is a true for all testing sites (so take cross-system test comparison tools with a grain of salt).

cheerio

Klaus
photozone.de
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RiceHigh's avatar - Go to profile

RiceHigh 110p · 695 weeks ago

The problem you encountered and mentioned is actually easily solved by testing the in-camera JPEG, and always, as this is the supposed to be optimised *complete* package that the camera manufacturer gave to the users! No matter how, this is what should be measured for how a camera performs, on its own!
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Raist3d · 694 weeks ago

No, it's not solved that way at all. JPEG engines vary very wildly and do not show the true potential of the camera if they have RAW capture. There are cameras with not so good JPEG engines but much better performance from raw - take Panasonic 4/3rds L10 or earlier micro four thirds they made for example.
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RiceHigh 110p · 694 weeks ago

If the in-camera JPEG engines are inferiors, the camera manufacturers deserved to get bad names because of they were made by themselves, but not by any 3rd parties!

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