[Scythels]

Regarding DxO,

 

I wouldn't call them "the benchmark" - they do far too many alterations of their data for that. 

 

Their lens tests are all bunk anyway, they attempt (and unsurprisingly, fail) to compute out the camera sensor involved and then extrapolate to other cameras without doing the test directly.

 

An MTF bench would be a good investment for them since they could then actually remove camera influence, but then DxO isn't interested in good data anyway =)  They're mathematicians, not optics graduates.

[Faketastic]

Canon 16-35/4 and Nikon 14-24 beat it, and Klaus + sony OIS = bad times for centering =)  This lens seems to have been an exception to that.

How in the world does the Canon beat it? The resolution is clearly much better with the Sony lens.

[youpii]

The center resolution of the 16-35/4 is quite amazing.

 

Another test that seems contradictory is on lenscore.org: only 731 as resolving power for the 16-35/4 but 889 for the 35/2.8

[soLong]

Hmmm, pardon silly old me with a general philosophical thought from a very wide pov….


<p style="font-size:12px;font-family:Helvetica;"> 

<p style="font-size:12px;font-family:Helvetica;">I had a 1635 once upon a time (not this lens obviously), it was just a tad soft at 35 but, more importantly for me, although the centre rez and exaggerated perspective produced interesting pictures at 16 what always attracted my attention was the, ahem slightly, soft and smeary distorted corners. If you want really wide spectacular pictures, why would you also want soft and smeary corners….Just a thought for the innocent customer putting such a lens on his ff camera to check out in the shop.

[Rover]

Hmmm, pardon silly old me with a general philosophical thought from a very wide pov….


<p style="font-family:Helvetica;"> 

<p style="font-family:Helvetica;">I had a 1635 once upon a time (not this lens obviously), it was just a tad soft at 35 but, more importantly for me, although the centre rez and exaggerated perspective produced interesting pictures at 16 what always attracted my attention was the, ahem slightly, soft and smeary distorted corners. If you want really wide spectacular pictures, why would you also want soft and smeary corners….Just a thought for the innocent customer putting such a lens on his ff camera to check out in the shop.

Beware! A lot of people would crucify you for that because they call that <b>lens character</b> and say that sharpness is boring (or, to quote more precisely, clinical).

[Klaus]

Hmmm, pardon silly old me with a general philosophical thought from a very wide pov….


<p style="font-family:Helvetica;"> 

<p style="font-family:Helvetica;">I had a 1635 once upon a time (not this lens obviously), it was just a tad soft at 35 but, more importantly for me, although the centre rez and exaggerated perspective produced interesting pictures at 16 what always attracted my attention was the, ahem slightly, soft and smeary distorted corners. If you want really wide spectacular pictures, why would you also want soft and smeary corners….Just a thought for the innocent customer putting such a lens on his ff camera to check out in the shop.

 

Hmmm, pardon silly old me with a general philosophical thought from a very wide pov….


<p style="font-family:Helvetica;"> 

<p style="font-family:Helvetica;">I had a 1635 once upon a time (not this lens obviously), it was just a tad soft at 35 but, more importantly for me, although the centre rez and exaggerated perspective produced interesting pictures at 16 what always attracted my attention was the, ahem slightly, soft and smeary distorted corners. If you want really wide spectacular pictures, why would you also want soft and smeary corners….Just a thought for the innocent customer putting such a lens on his ff camera to check out in the shop.

 

 

There is some field curvature at 16mm.

[Scythels]

How in the world does the Canon beat it? The resolution is clearly much better with the Sony lens.

A sensor with 55% more pixels inflates the numbers for sony's sensor.

 

The format for imatest results is lw/ph, if the lens and detector were perfect you would see a 1:1 correlation between lw/ph and the longest edge of the sensor in px. 

 

The 5D2 has 5600px long edge.  Peak imatest numbers for it are about 3850lw/ph but this is an exceptionally good lens performance (24L II at f/4) and the "true max" is about 3700.  Calculate the sensor's "resolution factor" here = 66% which is very expected.

 

A7r -> 7600px long edge.  Peak resolution is about 4700lw/ph or 61% which is a bit below expectation.  

 

We may bump canon's numbers by the % difference between the two in linear resolution = 7600/5600 = 35%.   

 

We may also add 10-15% on top of that for the removal of the AA filter but some may disagree with this so I will do it separately. 

 

16mm comparison:

 

Center:

    16-35/4L : 4800lw/ph

    16-35/4S : 4500lw/ph

Corner:

    16-35/4L : 3500lw/ph

    16-35/4S : 3199lw/ph

 

AA-filter compensated:

 

Center:

    16-35/4L : 5280lw/ph

    16-35/4S : 3850lw/ph

Corner:

    16-35/4L : 3500lw/ph

    16-35/4S : 3199lw/ph

 

Comparisons are pretty similar at other focal lengths. 

 

Canon also achieves this resolution with 50% less vignetting.  Not to mention the (astronomically) worse constraints because efl << bfl for the canon design. 

 

CAs on the canon are also about 1/2px or about (36/5600) = 1/2 * 6.4um = about 3.2um across the range.

 

Sony has about (36/7600) = 4.7um pixels * 1-2px of lateral CA = at least 4-8um of CA.

[Faketastic]

A sensor with 55% more pixels inflates the numbers for sony's sensor.

 

The format for imatest results is lw/ph, if the lens and detector were perfect you would see a 1:1 correlation between lw/ph and the longest edge of the sensor in px. 

 

The 5D2 has 5600px long edge.  Peak imatest numbers for it are about 3850lw/ph but this is an exceptionally good lens performance (24L II at f/4) and the "true max" is about 3700.  Calculate the sensor's "resolution factor" here = 66% which is very expected.

 

A7r -> 7600px long edge.  Peak resolution is about 4700lw/ph or 61% which is a bit below expectation.  

 

We may bump canon's numbers by the % difference between the two in linear resolution = 7600/5600 = 35%.   

 

We may also add 10-15% on top of that for the removal of the AA filter but some may disagree with this so I will do it separately. 

 

16mm comparison:

 

Center:

    16-35/4L : 4800lw/ph

    16-35/4S : 4500lw/ph

Corner:

    16-35/4L : 3500lw/ph

    16-35/4S : 3199lw/ph

 

AA-filter compensated:

 

Center:

    16-35/4L : 5280lw/ph

    16-35/4S : 3850lw/ph

Corner:

    16-35/4L : 3500lw/ph

    16-35/4S : 3199lw/ph

 

Comparisons are pretty similar at other focal lengths. 

 

Canon also achieves this resolution with 50% less vignetting.  Not to mention the (astronomically) worse constraints because efl << bfl for the canon design. 

 

CAs on the canon are also about 1/2px or about (36/5600) = 1/2 * 6.4um = about 3.2um across the range.

 

Sony has about (36/7600) = 4.7um pixels * 1-2px of lateral CA = at least 4-8um of CA.

 

I'm no expert in this but could you really bump resolution figures without knowing if the lens is the limiting factor? And what does Photozone's "excellent line"mean (which the Canon lens never passes outside the center).

 

It sounds like you're really want the Canon to be better...

[Scythels]

The change to resolution figures are to attempt to remove some of the sensor - the accuracy I would say is +/-10% as there really are no terrible sensors these days. 

 

One cannot compare the resolution of two lenses when the data is borne from a lens+sensor test combination.  If you put the 16-35/4L in front of the A7r and they were well matched to each other (meaning the cover glass on top of the A7r sensor is about 2mm thick) then you could directly compare the two. 

 

I did a bunch of rounding but changing things by +/-50lw/ph is pretty insignificant.  One would do the same compensations to upscale the 14-24 on the D3X to 36mp-equivalent figures.  The true bottom line is that in terms of resolution the performance is pretty similar, the canon is just much better at controlling CA and has less vignetting.  The sony has better distortion performance but neither is particularly offensive.

[dave9t5]

I'm no expert in this but could you really bump resolution figures without knowing if the lens is the limiting factor? And what does Photozone's "excellent line"mean (which the Canon lens never passes outside the center).

 

It sounds like you're really want the Canon to be better...

 

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:

<p style="margin-left:40px;">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 ?

<p style="margin-left:40px;">It depends on the similarities between the image sensor system. A sensor <i>SYSTEM</i><span style="color:rgb(51,51,51);font-family:Verdana, Helvetica, Arial, sans-serif;text-align:justify;"> 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).</span>

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

<p style="color:rgb(51,51,51);font-family:Verdana, Helvetica, Arial, sans-serif;font-size:12px;margin-left:40px;">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.