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02-27-2015, 10:43 PM

Quote:Scythels IS an expert and has given a very detailed and rational reply to your question to which your mind-boggling reaction is to snidely accuse him of an irrational bias.

You're certainly not an expert and the newbie here. Pay attention on the site and RTF:

http://www.opticallimits.com/Reviews/overview

http://www.opticallimits.com/Reviews/canon-eos-full

At the very top:

Please note that the tests results are not comparable across the different systems!

and

http://www.opticallimits.com/Reviews/lens-test-faq

Q: Are the figures comparable between cameras or different systems ?

It depends on the similarities between the image sensor system. A sensor SYSTEM contains the image sensor with or without micro-lenses, an IR filter, a low-pass (Moire) filter and the signal processing. As you can imagine the output quality is largely dependent on the whole chain on not just on the amount of megapixels. The different output quality between the Canon EOS 350D and the Olympus E-300 is a good example (despite a 8MP sensor). The tests are a good guidance for the lens quality as long as you compare the results WITHIN a test group (e.g. Canon).

Q: Why are the quality ratings different from system to system ?

As mentioned above the lens quality is affected by the sensor "system". Every additional step in the pipeline decreases the output quality, specifically the low-pass filter in front of the sensor. Assuming you mount the same lens on different system its maximum resolution will vary according to the max. quality of the sensor system. There're also evolutions regarding the RAW converter quality so more recent system tests starts can benefit from this - e.g. Canon/Olympus RAWs are/were converted using ACR 3.2 whereas Pentax/Sony RAWs are/were converted via ACR 3.7 and there was an increase in converter quality with ACR 3.4). This must all be taken into account regarding the rating system.

It's inherent that the tests here are system based and therefore difficult to compare. The accepted way to compare across tests is to compare the height of the bars on the graphs ex/very-good/etc, for example:

A visible difference is when about the difference between each level in rating on this scale. e.g., the scale about a difference of 500 LW/PH is visible.

Based on this, the Sony compared to the Canon is:

- Weaker wide open @ 35mm

- Corners don't catch up with the center (2 to 3 levels of difference), where the Canon is pretty even across the frame). That said, the super high res sensors do tend to exaggerate the differences between the center and edges, but conversely the short flange difference on the E-mount tends to lead to weak corners.

- Not bad on the CA but the Canon is suberb

They are both very fine lenses and the differences are pretty small but the Canon edges ahead in a few places.

And you accuse me of being a newbie..

You say:

1) You really can't compare system results "number by number"

2) Trust protozone's scaling with poor-ex rating

I just see the Sony spend more "time" in the ex range than the Canon lens. So, either PZ or Scythels is wrong then?

And a lens is worse because it's sharp in the center and not as even?

CA (if kept reasonably low) is not relevant with todays SW correction. The same goes for distorsion.