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next PZ lens test report: Sigma 24mm f/1.4 HSM DG "Art" ... on APS-C
#11
Took me a little while more, as lenscore doesn't have such a face comparison tool as DxO.

 

[Image: i-RdSBbCc-L.jpg]

 

Or a bit better to compare:

 

[Image: i-S99xSSH-L.png]

color scheme of the table was simply worst (red) and best (green) and the digram I made because I find it easier to see if the differences are big or just a tiny bit.

 

At the end, the difference between the Sigma and the Nikkor is peanuts, overall. I just don't see paying 60% less for equal performance not as peanuts.

#12
But at what distance does LensScore test =)  And what are the conditions of their "super sensor" line scanning device?  Does it utilize a cover glass?  If yes, what thickness?  How is focus defined?  Best on axis? 

#13
Does it matter, als long as it's the same value for all focal lengths in that class? Plus, I am not lenscore, so I think your questions would be better placed by addressing them. I am also not interested how they come to their absolute values, I'm using them as an additional comparison to other lens test sites. Do you have other findings over at lens rental's?

 

OLAF also uses the same methodical setup for all lenses and your testing them at infinity focus? So, let me ask, what good is a portrait lens or even a long tele at infinity, if my typical use is much closer? I'm not saying this to blame lens rental's being wrong - all I say is, you always need to look not at the test condiitons in the first place but if those are the same for every test. If no, I don't care about the results anymore, If yes, I can look bit closer. So far their findings were not far off what I see in reality, at least the bits I can see.

 

I also know DxO is more testing the lens/sensor combination - is that so bad? If one is lucky, they just have results for a particular combination. If one is unlucky - and your own work during the last months is proof enough that might happen - they just got the one better copy out of a batch and I buy one decenterred  with other flaws.

 

DxO and lensorg both lack the weakness to test just one copy. Other weaknesses you'd spot if you have enough insights, I'm sure. I say, all of you lens testers only show a piece of my reality and all test results show a tendency more than an absolute truth - at least that's what Roger never gets tired to tell in each disclaimer. There are values of a lens which are not so easy to be tested: How good's the OS / BR / IS / VC? How fast is the AF and how reliable? what will happen with it's mechanics over the years, in more demanding conditions?How good will an excellent modern lens work with a dated body and vice versa? Literally you lens testers are sitting in a glass house  ^_^ Sometimes I admire your work but I never look envy at it. Your delivering the ammunition to debates like these here (that's why I am here, too), but test pictures hardly become photographical masterworks. And once published they remain in place, no matter what a manufacturer could change in a probably weak production process.

#14
The issue of focusing distance comes much more into play with wide angles than telephotos.  A tele is going to behave quite similarly at 20ft as it will at 200ft or it will at infinity.  A retrofocus wide-angle will usually not behave at 2ft like it does at infinity.  So if lenstip is using a 4ft diameter chart, that's a problem.  Unless all you ever do it shoot around that focusing distance with your 24mm lenses =)  Even 8-10ft would be perfectly sufficient, but target size becomes impractical. 

 

The issue of a coverglass has to do with different cameras.  They have a "custom 200MP sensor" which to me is probably a line scanning device.  No coverglass is alright, the difference between 0 and 2mm (~canon or so) is not too enormous.  If it is more like 4-5mm, that is a big problem as it will inject simply enormous spherical aberration into the equation. 

 

The bigger issue with DxO is the amount of mathematics poorly applied to the data they gather.  An MTF bench does a huge amount of math to produce results, but it is all to resolve numbers out of the point spread function.  DxO's computations are to calculate the "max" resolution of the camera, which can't be known without a lens attached, weight the lens+camera res against camera+(what lens?), and other simply silly math. 

 

The testing done at OLAF on the ImageMaster is not without its caveats and issues so to speak, but no testing is which is why clearly defined and stated metrology parameters are needed.  Sadly, the latter is missing with most sources.

#15
Honestly, I think field curvature is the biggest issue regarding the transformation of the chart results to the real world.

 

I once did a ultra-wide test with the chart portions plugged to a wall - must have been 4x2.5m (15ft diameter) or something - and the difference compared to the chart results was marginal. Now this will not be the case across all lenses, of course. Some have better focus correction than others. However, if a lens performs weaker on a smaller chart, there's a message here anyway.

#16
The Voiltlander 20mm f3.5 SL II is a good example where focus distance matters a lot. At close® focus it shows huge astigmatism, so the closer you test, the worse the results will be. Yet at "infinity" it is quite a nice little lens.

#17
Quote:Took me a little while more, as lenscore doesn't have such a face comparison tool as DxO.

 

[Image: i-RdSBbCc-L.jpg]

 

Or a bit better to compare:

 

[Image: i-S99xSSH-L.png]

color scheme of the table was simply worst (red) and best (green) and the digram I made because I find it easier to see if the differences are big or just a tiny bit.

 

At the end, the difference between the Sigma and the Nikkor is peanuts, overall. I just don't see paying 60% less for equal performance not as peanuts.
If all the metrics on the chart follow the "more = better" rule, guess I'll have to cry blood tears because I bought the 24/1.4L for a hefty sum. Mind you, that was before the 24/1.4A was even announced, and the lens did come in handy a few times since then, but still... I'm starting to have a case of buyer's remorse.
#18
Quote:If all the metrics on the chart follow the "more = better" rule, guess I'll have to cry blood tears because I bought the 24/1.4L for a hefty sum. Mind you, that was before the 24/1.4A was even announced, and the lens did come in handy a few times since then, but still... I'm starting to have a case of buyer's remorse.
 Well, to comfort you I put the numbers in, too. Although most of the tested/measured parameters don't speak for the Canon, the differences are not that massive.

 

And you can always do what I did: Sell your Canon (except you're interested ind the best value in Lateral Color Abberation Wink ) and get the Sigma plus a nice dinner.

 

To me, the 24/1.4 was quite often very useful. I would give away other lenses more easily than that one.
#19
Quote: Well, to comfort you I put the numbers in, too. Although most of the tested/measured parameters don't speak for the Canon, the differences are not that massive.

 

And you can always do what I did: Sell your Canon (except you're interested ind the best value in Lateral Color Abberation Wink ) and get the Sigma plus a nice dinner.

 

To me, the 24/1.4 was quite often very useful. I would give away other lenses more easily than that one.
Well, the exchange rate has gone so wild since then that I wouldn't really win anything now. But I could have back then.

Not that the 24/1.4 L is a bad lens by any measure... I'll take comfort in the fact that it's weather sealed unlike the Sigma (the only glaring omission in the A series lenses... almost looks like they looked for a reason to create a flaw in it! Big Grin)
#20
Quote:Well, the exchange rate has gone so wild since then that I wouldn't really win anything now. But I could have back then.

Not that the 24/1.4 L is a bad lens by any measure... I'll take comfort in the fact that it's weather sealed unlike the Sigma (the only glaring omission in the A series lenses... almost looks like they looked for a reason to create a flaw in it! Big Grin)
It is weather sealed, and it may focus faster and more accurately (Canon USM). That the Sigma does better in corners wide open is not that important, as usually the subject is not in the corners. So, I would not think about it too much, unless you run into something in particular.
  


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