GX7 Lens Review on DxO

Started 7 months ago | Discussions
Enir4
Senior MemberPosts: 2,018Gear list
Like?
Re: GX7 Lens Review on DxO
In reply to Steen Bay, 7 months ago

Steen Bay wrote:

Enir4 wrote:

By the way, I also compared my NEX 7 with the 10-18mm lens set at 24mm equivalent with the GX7 with the 12-35 at 24mm equivalent. Aside from the usual difference in cliping highlights, there is nothing slight about the difference: the GX7 + 12-35 are just well above, in a different class. And yet DxO gives a score of 15 to the combination GX7 and 12-35, and 14 to the NEX 7 and 10-18. Sheer nonsense, the GX7 with 12-35 is MUCH better. Something went very wrong with DxO's testing.

Enrique

DxO's P-Mpix score for the two combinations are like this :

GX7/12-35 - 5 P-Mpix

NEX-7/10-18 - 9 P-Mpix

Well, even worse. It's sheer nonsense.

Enrique

 Enir4's gear list:Enir4's gear list
Fujifilm FinePix X100 Panasonic Lumix DMC-GX7 Olympus E-M1 Panasonic Lumix G Vario 7-14mm F4 ASPH Panasonic Leica DG Macro-Elmarit 45mm F2.8 ASPH OIS +5 more
Reply   Reply with quote   Complain
Anders W
Forum ProPosts: 17,051Gear list
Like?
Re: DxO's Comments on this...Strong AA Filter?
In reply to MarkyM, 7 months ago

MarkyM wrote:

Anders W wrote:

MarkyM wrote:

Emilie from DxO has commented on their site saying they "guess" it is a strong AA filter:

"Yes, this is something we checked many times before publish it,...
Sharpness measured on GX7 is a bit low, but pretty close to the GX1 results. We guess there is a strong Anti Alias filter on this cameras."

It seems to me they did something wrong or had a bad unit.

Strong AA filter as an explanation for this kind of discrepancy (worst results for any MFT camera ever tested, including all those with 12 MP sensors)? No way. If that had actually been the case (which is of course extremely unlikely in the first place), it would have been known long ago. Several test sites (inluding SLR Gear/Imaging Resources and optyczne.pl, the Polish counterpart) have looked at the resolution of the sensor without finding anything unusual.

So DxO made a mistake or had a faulty unit. What is really weird is that they went ahead and published the results in spite of the fact that something is clearly wrong.

Agreed.

FYI anyone can register and comment to their thread here:

http://www.dxomark.com/Reviews/Best-lenses-for-the-16-MPix-Panasonic-Lumix-DMC-GX7-Part-1

Maybe we can get them to re-test.

Great minds think alike. I have already posted on their forum. Not the same thread as yours but one of several about the matter right now.

http://forum.dxomark.com/index.php/topic,1808.msg3591/topicseen.html#msg3591

Others are more than welcome to do the same.

 Anders W's gear list:Anders W's gear list
Panasonic Lumix DMC-G1 Olympus OM-D E-M5 Olympus E-M1 Panasonic Lumix G Vario 14-45mm F3.5-5.6 ASPH OIS Panasonic Lumix G Vario 7-14mm F4 ASPH +21 more
Reply   Reply with quote   Complain
Anders W
Forum ProPosts: 17,051Gear list
Like?
Re: DxO's Comments on this...Strong AA Filter?
In reply to Steen Bay, 7 months ago

Steen Bay wrote:

Anders W wrote:

MarkyM wrote:

Emilie from DxO has commented on their site saying they "guess" it is a strong AA filter:

"Yes, this is something we checked many times before publish it,...
Sharpness measured on GX7 is a bit low, but pretty close to the GX1 results. We guess there is a strong Anti Alias filter on this cameras."

It seems to me they did something wrong or had a bad unit.

Strong AA filter as an explanation for this kind of discrepancy (worst results for any MFT camera ever tested, including all those with 12 MP sensors)? No way. If that had actually been the case (which is of course extremely unlikely in the first place), it would have been known long ago. Several test sites (inluding SLR Gear/Imaging Resources and optyczne.pl, the Polish counterpart) have looked at the resolution of the sensor without finding anything unusual.

So DxO made a mistake or had a faulty unit. What is really weird is that they went ahead and published the results in spite of the fact that something is clearly wrong.

Checked.. DxO has tested 29 different mFT lenses on 13 different mFT cameras (+ a few older lenses only on older cameras), and with every single of the 29 lenses the GX7 gets a very low score. Makes me wonder... mistakes happen, but 29 times in a row! Could it be that they don't actually test every single lens on every single body, but instead use the test result from one camera to derive/calculate the 'results' for all the other cameras?

No, I wouldn't think they'd dare to go that far (or that it is possible to do so "safely").

If doing it like that, then it's only necessary to test a single 'reference' lens on a new camera like the GX7. Saves a lot of work, but if something goes wrong, then all the derived results will be wrong too.

I initially suspected that they'd run into some kind of shutter-shock problem, perhaps some problem of that kind more or less unique to the particular copy of the camera they tested. On the other hand, one would then expect more problem with vertical than horizontal resolution, and I didn't see anything suggesting that pattern when I had a look. OK, I certainly didn't check very thoroughly but anyway.

It could be something as mundane as a programming error, however. If they entered the wrong parameter/constant when going from their raw observations to the final acutance and P-MPix scores, all the values will of course be off in the same direction.

I am still not sure we can entirely exclude the shutter-shock hypothesis, however. I had a look at the review of the GX7 by optyczne.pl (Lenstip but in Polish) and they apparently ran into a problem with suspiciously low resolution values which forced them to switch to the electronic shutter to get proper values in that department. See here:

http://www.optyczne.pl/239.4-Test_aparatu-Panasonic_Lumix_DMC-GX7_Rozdzielczość.html

 Anders W's gear list:Anders W's gear list
Panasonic Lumix DMC-G1 Olympus OM-D E-M5 Olympus E-M1 Panasonic Lumix G Vario 14-45mm F3.5-5.6 ASPH OIS Panasonic Lumix G Vario 7-14mm F4 ASPH +21 more
Reply   Reply with quote   Complain
Steen Bay
Veteran MemberPosts: 6,188
Like?
Re: DxO's Comments on this...Strong AA Filter?
In reply to Anders W, 7 months ago

Anders W wrote:

Steen Bay wrote:

Anders W wrote:

MarkyM wrote:

Emilie from DxO has commented on their site saying they "guess" it is a strong AA filter:

"Yes, this is something we checked many times before publish it,...
Sharpness measured on GX7 is a bit low, but pretty close to the GX1 results. We guess there is a strong Anti Alias filter on this cameras."

It seems to me they did something wrong or had a bad unit.

Strong AA filter as an explanation for this kind of discrepancy (worst results for any MFT camera ever tested, including all those with 12 MP sensors)? No way. If that had actually been the case (which is of course extremely unlikely in the first place), it would have been known long ago. Several test sites (inluding SLR Gear/Imaging Resources and optyczne.pl, the Polish counterpart) have looked at the resolution of the sensor without finding anything unusual.

So DxO made a mistake or had a faulty unit. What is really weird is that they went ahead and published the results in spite of the fact that something is clearly wrong.

Checked.. DxO has tested 29 different mFT lenses on 13 different mFT cameras (+ a few older lenses only on older cameras), and with every single of the 29 lenses the GX7 gets a very low score. Makes me wonder... mistakes happen, but 29 times in a row! Could it be that they don't actually test every single lens on every single body, but instead use the test result from one camera to derive/calculate the 'results' for all the other cameras?

No, I wouldn't think they'd dare to go that far (or that it is possible to do so "safely").

Hope they don't dare, but doing it the proper/correct way means lots of hard work.

"For each focal length and aperture of the lens, we take pictures at 60 different focusing positions around the focusing point set by the camera's autofocus system. We then use the sharpest image to measure the camera’s MTF."

http://www.dxomark.com/en่%20%20้ฉด้%20%20็%20%20่%20%20้ฉด้%20%20้ฉด่%20%20้ฉด้%20%20้%20%20/About/In-depth-measurements/DxOMark-testing-protocols/MTF

60 images for each tested FL and f-stop. That's a lot of images for 29 lenses tested on 13 different cameras, and that's just mFT.

If doing it like that, then it's only necessary to test a single 'reference' lens on a new camera like the GX7. Saves a lot of work, but if something goes wrong, then all the derived results will be wrong too.

I initially suspected that they'd run into some kind of shutter-shock problem, perhaps some problem of that kind more or less unique to the particular copy of the camera they tested. On the other hand, one would then expect more problem with vertical than horizontal resolution, and I didn't see anything suggesting that pattern when I had a look. OK, I certainly didn't check very thoroughly but anyway.

It could be something as mundane as a programming error, however. If they entered the wrong parameter/constant when going from their raw observations to the final acutance and P-MPix scores, all the values will of course be off in the same direction.

I am still not sure we can entirely exclude the shutter-shock hypothesis, however. I had a look at the review of the GX7 by optyczne.pl (Lenstip but in Polish) and they apparently ran into a problem with suspiciously low resolution values which forced them to switch to the electronic shutter to get proper values in that department. See here:

http://www.optyczne.pl/239.4-Test_aparatu-Panasonic_Lumix_DMC-GX7_Rozdzielczość.html

Interesting. My Polish ain't that good, but the graph shows clearly that the electronic shutter on GX7 gives sharper images (which shutter speeds?). Seems that the GX1 has a suspiciously low resolution too.

Reply   Reply with quote   Complain
Anders W
Forum ProPosts: 17,051Gear list
Like?
Re: DxO's Comments on this...Strong AA Filter?
In reply to Steen Bay, 7 months ago

Steen Bay wrote:

Anders W wrote:

Steen Bay wrote:

Anders W wrote:

MarkyM wrote:

Emilie from DxO has commented on their site saying they "guess" it is a strong AA filter:

"Yes, this is something we checked many times before publish it,...
Sharpness measured on GX7 is a bit low, but pretty close to the GX1 results. We guess there is a strong Anti Alias filter on this cameras."

It seems to me they did something wrong or had a bad unit.

Strong AA filter as an explanation for this kind of discrepancy (worst results for any MFT camera ever tested, including all those with 12 MP sensors)? No way. If that had actually been the case (which is of course extremely unlikely in the first place), it would have been known long ago. Several test sites (inluding SLR Gear/Imaging Resources and optyczne.pl, the Polish counterpart) have looked at the resolution of the sensor without finding anything unusual.

So DxO made a mistake or had a faulty unit. What is really weird is that they went ahead and published the results in spite of the fact that something is clearly wrong.

Checked.. DxO has tested 29 different mFT lenses on 13 different mFT cameras (+ a few older lenses only on older cameras), and with every single of the 29 lenses the GX7 gets a very low score. Makes me wonder... mistakes happen, but 29 times in a row! Could it be that they don't actually test every single lens on every single body, but instead use the test result from one camera to derive/calculate the 'results' for all the other cameras?

No, I wouldn't think they'd dare to go that far (or that it is possible to do so "safely").

Hope they don't dare, but doing it the proper/correct way means lots of hard work.

"For each focal length and aperture of the lens, we take pictures at 60 different focusing positions around the focusing point set by the camera's autofocus system. We then use the sharpest image to measure the camera’s MTF."

http://www.dxomark.com/en่%20%20้ฉด้%20%20็%20%20่%20%20้ฉด้%20%20้ฉด่%20%20้ฉด้%20%20้%20%20/About/In-depth-measurements/DxOMark-testing-protocols/MTF

60 images for each tested FL and f-stop. That's a lot of images for 29 lenses tested on 13 different cameras, and that's just mFT.

Yes, I know. It seems like they would have a lot to do. And every time they add a lens or a camera, they have more and more combinations to test. Seems like a somewhat Sisyphusian task.

I am trying, since some weeks, to ask them questions about their lens test procedures on DxO's own forum. As you can see here

http://forum.dxomark.com/index.php/topic,1757.msg3592/topicseen.html#msg3592

I haven't got much in the way of respnses yet, but I'll keep asking and will try to remember your question as to whether they actually test all combinations as well. Or feel free to jump into that thread and ask it yourself. The more we are putting pressure on them to respond, the better.

If doing it like that, then it's only necessary to test a single 'reference' lens on a new camera like the GX7. Saves a lot of work, but if something goes wrong, then all the derived results will be wrong too.

I initially suspected that they'd run into some kind of shutter-shock problem, perhaps some problem of that kind more or less unique to the particular copy of the camera they tested. On the other hand, one would then expect more problem with vertical than horizontal resolution, and I didn't see anything suggesting that pattern when I had a look. OK, I certainly didn't check very thoroughly but anyway.

It could be something as mundane as a programming error, however. If they entered the wrong parameter/constant when going from their raw observations to the final acutance and P-MPix scores, all the values will of course be off in the same direction.

I am still not sure we can entirely exclude the shutter-shock hypothesis, however. I had a look at the review of the GX7 by optyczne.pl (Lenstip but in Polish) and they apparently ran into a problem with suspiciously low resolution values which forced them to switch to the electronic shutter to get proper values in that department. See here:

http://www.optyczne.pl/239.4-Test_aparatu-Panasonic_Lumix_DMC-GX7_Rozdzielczość.html

Interesting. My Polish ain't that good, but the graph shows clearly that the electronic shutter on GX7 gives sharper images (which shutter speeds?). Seems that the GX1 has a suspiciously low resolution too.

Yes, judging by one of the diagrams, the GX1 looks even worse (although they do not comment on the reason in that case). Regrettably, they don't say anything about the shutter speeds used either.

 Anders W's gear list:Anders W's gear list
Panasonic Lumix DMC-G1 Olympus OM-D E-M5 Olympus E-M1 Panasonic Lumix G Vario 14-45mm F3.5-5.6 ASPH OIS Panasonic Lumix G Vario 7-14mm F4 ASPH +21 more
Reply   Reply with quote   Complain
Sergey Borachev
Senior MemberPosts: 2,480Gear list
Like?
Re: DxO's Comments on this...Strong AA Filter?
In reply to Anders W, 7 months ago

Anders W wrote:

MarkyM wrote:

Emilie from DxO has commented on their site saying they "guess" it is a strong AA filter:

"Yes, this is something we checked many times before publish it,...
Sharpness measured on GX7 is a bit low, but pretty close to the GX1 results. We guess there is a strong Anti Alias filter on this cameras."

It seems to me they did something wrong or had a bad unit.

Strong AA filter as an explanation for this kind of discrepancy (worst results for any MFT camera ever tested, including all those with 12 MP sensors)? No way. If that had actually been the case (which is of course extremely unlikely in the first place), it would have been known long ago. Several test sites (inluding SLR Gear/Imaging Resources and optyczne.pl, the Polish counterpart) have looked at the resolution of the sensor without finding anything unusual.

So DxO made a mistake or had a faulty unit. What is really weird is that they went ahead and published the results in spite of the fact that something is clearly wrong.

Mistakes happen. OK. However such mistake should be easy to detect and in this case it shoudl be obvious that something is wrong, if DxO has any kind of reasonableness check, which can be very simple ones, e.g. comparing with similar cameras/sensors/ and old models from the same manufacturer. Even a casual look at the results should trigger alarm bells, for people who do this kind of work in any professional manner. This is strange. On the other hand, when the E-M5 was tested, there was apparent disbelief and reluctance to release the superior performance results. DxO took about 6 months after testing to release their results. For all we know, there could have been some extra diligent checking that time, and perhaps (pure guessing) even adjustments to scoring methods and re-tests. There have just been too much mystery, inconsistencies, and strange cases for me to have confidence in their test results, which often seem to be biased against M43 products.

Reply   Reply with quote   Complain
Ken Strain
Regular MemberPosts: 222
Like?
Re: DxO's Comments on this...Strong AA Filter?
In reply to Anders W, 7 months ago

Anders W wrote:

Steen Bay wrote:

Anders W wrote:

MarkyM wrote:

Emilie from DxO has commented on their site saying they "guess" it is a strong AA filter:

"Yes, this is something we checked many times before publish it,...
Sharpness measured on GX7 is a bit low, but pretty close to the GX1 results. We guess there is a strong Anti Alias filter on this cameras."

It seems to me they did something wrong or had a bad unit.

Strong AA filter as an explanation for this kind of discrepancy (worst results for any MFT camera ever tested, including all those with 12 MP sensors)? No way. If that had actually been the case (which is of course extremely unlikely in the first place), it would have been known long ago. Several test sites (inluding SLR Gear/Imaging Resources and optyczne.pl, the Polish counterpart) have looked at the resolution of the sensor without finding anything unusual.

So DxO made a mistake or had a faulty unit. What is really weird is that they went ahead and published the results in spite of the fact that something is clearly wrong.

Checked.. DxO has tested 29 different mFT lenses on 13 different mFT cameras (+ a few older lenses only on older cameras), and with every single of the 29 lenses the GX7 gets a very low score. Makes me wonder... mistakes happen, but 29 times in a row! Could it be that they don't actually test every single lens on every single body, but instead use the test result from one camera to derive/calculate the 'results' for all the other cameras?

No, I wouldn't think they'd dare to go that far (or that it is possible to do so "safely").

If doing it like that, then it's only necessary to test a single 'reference' lens on a new camera like the GX7. Saves a lot of work, but if something goes wrong, then all the derived results will be wrong too.

I initially suspected that they'd run into some kind of shutter-shock problem, perhaps some problem of that kind more or less unique to the particular copy of the camera they tested. On the other hand, one would then expect more problem with vertical than horizontal resolution, and I didn't see anything suggesting that pattern when I had a look. OK, I certainly didn't check very thoroughly but anyway.

It could be something as mundane as a programming error, however. If they entered the wrong parameter/constant when going from their raw observations to the final acutance and P-MPix scores, all the values will of course be off in the same direction.

I am still not sure we can entirely exclude the shutter-shock hypothesis, however. I had a look at the review of the GX7 by optyczne.pl (Lenstip but in Polish) and they apparently ran into a problem with suspiciously low resolution values which forced them to switch to the electronic shutter to get proper values in that department. See here:

http://www.optyczne.pl/239.4-Test_aparatu-Panasonic_Lumix_DMC-GX7_Rozdzielczość.html

Hi Anders,

A few observations and comments (no conclusions yet):

I checked the sigma 60mm at f/4 with the EM5 and GX7 on DXOmark for PMpix and acutance at the image centre at about the sharpest aperture:

  • It is likely that the relation from PMpix to some MTF measure involves a square root - so the linear measures would differ by sqrt(11/6) ~ 1.35+/- 0.02 (error from the rounding of PMpix to one significant figure).
  • Out of curiosity I applied my model for estimating MTF50 from the DXO acutance, and get 945 : 716 cycles/picture height, or a ratio of 1.32.

The GX1 is much closer to the EM5 on DXO (within 10+/-5% in linear measure). So the quote from up-thread that the GX7 is "pretty close to GX1 results" is hard to understand. It looks like an outlier to me.

Although I have only measured the vibration of one GX7 (and no EM5s), I will be a little surprised if it is concluded that there is a general problem with the GX7. There is the possibility that internal resonances of particular mounts (tripod/head/etc.) interact with the internal dynamics of the camera to make things worse.

It is pretty bad news if even half the discrepancy is from the measurement, as that spans the range from a good lens to exceptional one.

Ken

ps., mildly amusing (perhaps) trick question: which has higher "acutance" a Sigma 60mm at f/4 on the EM5 or a Zeiss APO Sonnar 135/2 on a Nikon D4 at f/8? (Apertures were chosen as the ones I would use most often, and of course the cameras both have 16 Mpixels).

Answer: neither - the Sigma/EM5 combination is marginally better in frame centre, but marginally worse at the edges). PMpix scores are 11 and 15, respectively. I think the price and weight of these combinations differs by more than the quality of the result.

At the moment the whole business seems like a bad joke.

Reply   Reply with quote   Complain
Anders W
Forum ProPosts: 17,051Gear list
Like?
Re: DxO's Comments on this...Strong AA Filter?
In reply to Ken Strain, 7 months ago

Ken Strain wrote:

Anders W wrote:

Steen Bay wrote:

Anders W wrote:

MarkyM wrote:

Emilie from DxO has commented on their site saying they "guess" it is a strong AA filter:

"Yes, this is something we checked many times before publish it,...
Sharpness measured on GX7 is a bit low, but pretty close to the GX1 results. We guess there is a strong Anti Alias filter on this cameras."

It seems to me they did something wrong or had a bad unit.

Strong AA filter as an explanation for this kind of discrepancy (worst results for any MFT camera ever tested, including all those with 12 MP sensors)? No way. If that had actually been the case (which is of course extremely unlikely in the first place), it would have been known long ago. Several test sites (inluding SLR Gear/Imaging Resources and optyczne.pl, the Polish counterpart) have looked at the resolution of the sensor without finding anything unusual.

So DxO made a mistake or had a faulty unit. What is really weird is that they went ahead and published the results in spite of the fact that something is clearly wrong.

Checked.. DxO has tested 29 different mFT lenses on 13 different mFT cameras (+ a few older lenses only on older cameras), and with every single of the 29 lenses the GX7 gets a very low score. Makes me wonder... mistakes happen, but 29 times in a row! Could it be that they don't actually test every single lens on every single body, but instead use the test result from one camera to derive/calculate the 'results' for all the other cameras?

No, I wouldn't think they'd dare to go that far (or that it is possible to do so "safely").

If doing it like that, then it's only necessary to test a single 'reference' lens on a new camera like the GX7. Saves a lot of work, but if something goes wrong, then all the derived results will be wrong too.

I initially suspected that they'd run into some kind of shutter-shock problem, perhaps some problem of that kind more or less unique to the particular copy of the camera they tested. On the other hand, one would then expect more problem with vertical than horizontal resolution, and I didn't see anything suggesting that pattern when I had a look. OK, I certainly didn't check very thoroughly but anyway.

It could be something as mundane as a programming error, however. If they entered the wrong parameter/constant when going from their raw observations to the final acutance and P-MPix scores, all the values will of course be off in the same direction.

I am still not sure we can entirely exclude the shutter-shock hypothesis, however. I had a look at the review of the GX7 by optyczne.pl (Lenstip but in Polish) and they apparently ran into a problem with suspiciously low resolution values which forced them to switch to the electronic shutter to get proper values in that department. See here:

http://www.optyczne.pl/239.4-Test_aparatu-Panasonic_Lumix_DMC-GX7_Rozdzielczość.html

Hi Anders,

A few observations and comments (no conclusions yet):

I checked the sigma 60mm at f/4 with the EM5 and GX7 on DXOmark for PMpix and acutance at the image centre at about the sharpest aperture:

  • It is likely that the relation from PMpix to some MTF measure involves a square root - so the linear measures would differ by sqrt(11/6) ~ 1.35+/- 0.02 (error from the rounding of PMpix to one significant figure).
  • Out of curiosity I applied my model for estimating MTF50 from the DXO acutance, and get 945 : 716 cycles/picture height, or a ratio of 1.32.

Yes, and that's a pretty sizeable difference.

The GX1 is much closer to the EM5 on DXO (within 10+/-5% in linear measure). So the quote from up-thread that the GX7 is "pretty close to GX1 results" is hard to understand. It looks like an outlier to me.

Sure does to me as well.

Although I have only measured the vibration of one GX7 (and no EM5s), I will be a little surprised if it is concluded that there is a general problem with the GX7. There is the possibility that internal resonances of particular mounts (tripod/head/etc.) interact with the internal dynamics of the camera to make things worse.

Agree here too. My impression so far based on various indications (your own tests, DPR studio scene samples, where there seems to be less of a problem with the GX7 than with other MFT cameras in the critical range of shutter speeds, and SLRGear's observations in conjunction with their test of the new Pany 14-140) all suggest to me that the GX7 is not particularly problematic from a shutter-shock point of view. The GX1, by contrast, seems to be among the worst offenders here.

It is pretty bad news if even half the discrepancy is from the measurement, as that spans the range from a good lens to exceptional one.

Certainly.

Ken

ps., mildly amusing (perhaps) trick question: which has higher "acutance" a Sigma 60mm at f/4 on the EM5 or a Zeiss APO Sonnar 135/2 on a Nikon D4 at f/8? (Apertures were chosen as the ones I would use most often, and of course the cameras both have 16 Mpixels).

Answer: neither - the Sigma/EM5 combination is marginally better in frame centre, but marginally worse at the edges). PMpix scores are 11 and 15, respectively. I think the price and weight of these combinations differs by more than the quality of the result.

At the moment the whole business seems like a bad joke.

Indeed.

P.S. I am sorry I hadn't found the time to comment on (and ask questions about) your shutter-shock tests in further detail yet. It's just that I need a bit more time for digesting things before I do.

 Anders W's gear list:Anders W's gear list
Panasonic Lumix DMC-G1 Olympus OM-D E-M5 Olympus E-M1 Panasonic Lumix G Vario 14-45mm F3.5-5.6 ASPH OIS Panasonic Lumix G Vario 7-14mm F4 ASPH +21 more
Reply   Reply with quote   Complain
Dimpsey
New MemberPosts: 2
Like?
Re: GX7 Lens Review on DxO
In reply to Ultbruin, 7 months ago

Been using the GX7 and found:

  1. The GX7's prime 20mm f/1.7 compared with Olympus EPL5's kit zoom 14-42mm - incidentally thinking that's a very good example - the GX7 was sharper at moderate apertures, as expected of a prime vs. zoom comparison.
  2. Stopping the GX7 down to f/16 showed noticeable, pronounced softness, possibly diffraction effect due to small sensor size relative to 35mm full frame. EPL5 suffers similar effect, the drop off a little less pronounced; but then the overall sharpness at f/8 was less too, so this a very subjective view.
  3. Consider the dynamic range of the GX7 to be less than the EPL5, especially in contre-jour landscape shots. Also consider the colour from the GX7 takes more adjustment than the [to me, very] pleasing Olympus palette - again a very subjective view as dependent on eyesight!

On a completely different theme, the difference in straight GX7 jpegs vs. ACR - or Dxo - RAW processing was astonishing, giving a dramatically different-shaped histogram every time. Since the EPL5 can shoot RAW only, have no jpeg comparisons to look at, but will say there's no way I'd want to shoot GX7 jpegs and expect high quality images.

Reply   Reply with quote   Complain
Pictures shooter
New MemberPosts: 17Gear list
Like?
Re: GX7 Lens Review on DxO
In reply to Enir4, 7 months ago

I was trying to find clear words how can we call such magic testing...

It was not incorrect or unskilful testing of cameras.... no... it was testing of DxO absurd methodology itself with its farfetched Perceptual "P-Mpix"... and this odd methodology  failed the exam...

 Pictures shooter's gear list:Pictures shooter's gear list
Panasonic Lumix DMC-G5 Sony Alpha NEX-6 Panasonic Lumix DMC-GX7 Sony Alpha 7R
Reply   Reply with quote   Complain
jalywol
jalywol MOD
Veteran MemberPosts: 4,936Gear list
Like?
Re: GX7 Lens Review on DxO
In reply to Dimpsey, 7 months ago

Dimpsey wrote:

On a completely different theme, the difference in straight GX7 jpegs vs. ACR - or Dxo - RAW processing was astonishing, giving a dramatically different-shaped histogram every time. Since the EPL5 can shoot RAW only, have no jpeg comparisons to look at, but will say there's no way I'd want to shoot GX7 jpegs and expect high quality images.

Not sure if this is what you are actually saying, but you CAN shoot RAW + JPG with the EPL5.....

-J

Reply   Reply with quote   Complain
cameron2
Senior MemberPosts: 1,051Gear list
Like?
Re: GX7 Lens Review on DxO
In reply to Pictures shooter, 7 months ago

Pictures shooter wrote:

It would be nice to get a sample of a grass they were smoking.
I see that Olympus 75mm F1.8 on old, more than four-year old Panasonic GH1 has 9 mysterious units called "P-Mpix",
but the same lens on GX7 provides only miserable 7 "P-Mpix",
and even the oldest, I would say ancient, five-year (!) Panasonic G1 still provides 8 "P-Mpix".
Panasonic's development team are not even able just to repeat its result of distant past 2008...
It's too far beyond the bound of any explicable common sense.
It looks like DxO use some magic coefficient that depends on how well should go sales of competing vendor cameras...

I assume that we will eventually learn the logical explanation behind the test results. It seems unlikely that DXO is trying to make the GX7 look bad. My guess is that there is a legitimate issue that threw their tests off; the question is how often that particular issue affects people using the GX7 in real life. (This reminds me a bit of the banding issue with the Pany 20mm a while back, where most people didn't have the issue, and the underlying cause was very hard to imagine.)

 cameron2's gear list:cameron2's gear list
Sony RX100 Panasonic Lumix DMC-GH2 Panasonic Lumix DMC-GF3 Panasonic Lumix DMC-GX7 Panasonic Lumix G Vario 14-45mm F3.5-5.6 ASPH OIS +16 more
Reply   Reply with quote   Complain
Dimpsey
New MemberPosts: 2
Like?
Re: GX7 Lens Review on DxO
In reply to jalywol, 7 months ago

Apologies for sloppy language jalywol. Yes, you can shoot Raw and jpegs with the EPL5. However, when the GX7 was first acquired, the only compatible RAW processor was Silkypix from Panasonic. This was unfamiliar and as good results were not immediately obtained, jpegs and RAW were taken as a stop-gap measure. Only out of curiosity were GX7 RAW and jpegs subsequently compared using an updated RAW processor.

The point being, having compared them, will stick with RAW, definitely. Jpegs have now been turned off in the GX7.

Reply   Reply with quote   Complain
Alexis D
Regular MemberPosts: 382
Like?
Re: DxO's Comments on this...Strong AA Filter?
In reply to Ken Strain, 7 months ago

Ken Strain wrote:

Anders W wrote:

Steen Bay wrote:

Anders W wrote:

MarkyM wrote:

Emilie from DxO has commented on their site saying they "guess" it is a strong AA filter:

"Yes, this is something we checked many times before publish it,...
Sharpness measured on GX7 is a bit low, but pretty close to the GX1 results. We guess there is a strong Anti Alias filter on this cameras.u

It seems to me they did something wrong or had a bad unit.

Strong AA filter as an explanation for this kind of discrepancy (worst results for any MFT camera ever tested, including all those with 12 MP sensors)? No way. If that had actually been the case (which is of course extremely unlikely in the first place), it would have been known long ago. Several test sites (inluding SLR Gear/Imaging Resources and optyczne.pl, the Polish counterpart) have looked at the resolution of the sensor without finding anything unusual.

So DxO made a mistake or had a faulty unit. What is really weird is that they went ahead and published the results in spite of the fact that something is clearly wrong.

Checked.. DxO has tested 29 different mFT lenses on 13 different mFT cameras (+ a few older lenses only on older cameras), and with every single of the 29 lenses the GX7 gets a very low score. Makes me wonder... mistakes happen, but 29 times in a row! Could it be that they don't actually test every single lens on every single body, but instead use the test result from one camera to derive/calculate the 'results' for all the other cameras?

No, I wouldn't think they'd dare to go that far (or that it is possible to do so "safely").

If doing it like that, then it's only necessary to test a single 'reference' lens on a new camera like the GX7. Saves a lot of work, but if something goes wrong, then all the derived results will be wrong too.

I initially suspected that they'd run into some kind of shutter-shock problem, perhaps some problem of that kind more or less unique to the particular copy of the camera they tested. On the other hand, one would then expect more problem with vertical than horizontal resolution, and I didn't see anything suggesting that pattern when I had a look. OK, I certainly didn't check very thoroughly but anyway.

It could be something as mundane as a programming error, however. If they entered the wrong parameter/constant when going from their raw observations to the final acutance and P-MPix scores, all the values will of course be off in the same direction.

I am still not sure we can entirely exclude the shutter-shock hypothesis, however. I had a look at the review of the GX7 by optyczne.pl (Lenstip but in Polish) and they apparently ran into a problem with suspiciously low resolution values which forced them to switch to the electronic shutter to get proper values in that department. See here:

http://www.optyczne.pl/239.4-Test_aparatu-Panasonic_Lumix_DMC-GX7_Rozdzielczość.html

Hi Anders,

A few observations and comments (no conclusions yet):

I checked the sigma 60mm at f/4 with the EM5 and GX7 on DXOmark for PMpix and acutance at the image centre at about the sharpest aperture:

  • It is likely that the relation from PMpix to some MTF measure involves a square root - so the linear measures would differ by sqrt(11/6) ~ 1.35+/- 0.02 (error from the rounding of PMpix to one significant figure).
  • Out of curiosity I applied my model for estimating MTF50 from the DXO acutance, and get 945 : 716 cycles/picture height, or a ratio of 1.32.

The GX1 is much closer to the EM5 on DXO (within 10+/-5% in linear measure). So the quote from up-thread that the GX7 is "pretty close to GX1 results" is hard to understand. It looks like an outlier to me.

Although I have only measured the vibration of one GX7 (and no EM5s), I will be a little surprised if it is concluded that there is a general problem with the GX7. There is the possibility that internal resonances of particular mounts (tripod/head/etc.) interact with the internal dynamics of the camera to make things worse.

It is pretty bad news if even half the discrepancy is from the measurement, as that spans the range from a good lens to exceptional one.

Ken

ps., mildly amusing (perhaps) trick question: which has higher "acutance" a Sigma 60mm at f/4 on the EM5 or a Zeiss APO Sonnar 135/2 on a Nikon D4 at f/8? (Apertures were chosen as the ones I would use most often, and of course the cameras both have 16 Mpixels).

Answer: neither - the Sigma/EM5 combination is marginally better in frame centre, but marginally worse at the edges). PMpix scores are 11 and 15, respectively. I think the price and weight of these combinations differs by more than the qu

ality of the result.

At the moment the whole business seems like a bad joke.

Trick question not so tricky. I suspected some answer like that.
I think DxO is confusing real test results with expected results and just publish expected results. Surely big dollar product and big brand products with big marketing pockets are expected to have better test results.

Reply   Reply with quote   Complain
gteague
Contributing MemberPosts: 930Gear list
Like?
Re: DxO's Comments on this...Strong AA Filter?
In reply to Alexis D, 7 months ago

yeah, i'm so disappointed in the dxo gx7 numbers i think i'll throw it on ebay for some sucker to buy:

... not.

/guy

-- hide signature --

"The world is going to pieces and people like Adams and Weston are photographing rocks!" ~Henri Cartier-Bresson

 gteague's gear list:gteague's gear list
Sony RX100 RX100 III Panasonic Lumix DMC-GX1 Panasonic Lumix DMC-GX7 Olympus M.Zuiko Digital ED 9-18mm 1:4.0-5.6 +4 more
Reply   Reply with quote   Complain
jhinkey
Senior MemberPosts: 2,321Gear list
Like?
Re: GX7 Lens Review on DxO
In reply to Ultbruin, 7 months ago

Completely non-scientific, but my initial shots on my just-delivered-today GX7 with one of the sharpest lenses I've ever owned - the Leica 180/3.4 APO Telyt - indicates that the sensor is doing just fine sharpness-wise. I see nothing that left me wanting . . .

see:  http://www.dpreview.com/forums/thread/3594576

 jhinkey's gear list:jhinkey's gear list
Panasonic Lumix DMC-TS3 Panasonic Lumix DMC-LX7 Panasonic Lumix DMC-GH2 Nikon D800 Panasonic Lumix DMC-G5 +19 more
Reply   Reply with quote   Complain
Joel Stern
Forum ProPosts: 10,142Gear list
Like?
So does the GX7 have an AA filter, I thought not
In reply to Ultbruin, 7 months ago

I remember threads from 2 weeks ago on this... So what is the answer?

-
If i am typing on my iPad, please excuse any typos.

Reply   Reply with quote   Complain
gteague
Contributing MemberPosts: 930Gear list
Like?
Re: GX7 Lens Review on DxO
In reply to jhinkey, 7 months ago

jhinkey wrote:

Completely non-scientific, but my initial shots on my just-delivered-today GX7 with one of the sharpest lenses I've ever owned - the Leica 180/3.4 APO Telyt - indicates that the sensor is doing just fine sharpness-wise. I see nothing that left me wanting . . .

see: http://www.dpreview.com/forums/thread/3594576

i like the shots. but is this with a full frame 180mm, i.e., a 360mm (in 35mm terms) equivalent? i'm totally not familiar with that lens unless it's an older leitz 90mm and you are giving it in 35mm equiv terms. if that's not the case and it's really a 180mm, the min shutter speed would be 1/360th, not 180th.

/guy

-- hide signature --

"The world is going to pieces and people like Adams and Weston are photographing rocks!" ~Henri Cartier-Bresson

 gteague's gear list:gteague's gear list
Sony RX100 RX100 III Panasonic Lumix DMC-GX1 Panasonic Lumix DMC-GX7 Olympus M.Zuiko Digital ED 9-18mm 1:4.0-5.6 +4 more
Reply   Reply with quote   Complain
jhinkey
Senior MemberPosts: 2,321Gear list
Like?
Re: GX7 Lens Review on DxO
In reply to gteague, 7 months ago

gteague wrote:

jhinkey wrote:

Completely non-scientific, but my initial shots on my just-delivered-today GX7 with one of the sharpest lenses I've ever owned - the Leica 180/3.4 APO Telyt - indicates that the sensor is doing just fine sharpness-wise. I see nothing that left me wanting . . .

see: http://www.dpreview.com/forums/thread/3594576

i like the shots. but is this with a full frame 180mm, i.e., a 360mm (in 35mm terms) equivalent? i'm totally not familiar with that lens unless it's an older leitz 90mm and you are giving it in 35mm equiv terms. if that's not the case and it's really a 180mm, the min shutter speed would be 1/360th, not 180th.

/guy

-- hide signature --

"The world is going to pieces and people like Adams and Weston are photographing rocks!" ~Henri Cartier-Bresson

It's a 180mm lens which would give a 360mm or so equivalent FOV on 35mm. As I stated in the other thread the min shutter speed would be 1/360 sec (~1/(2xFL) - perhaps I forgot a set of parentheses in the other post).

See here for info on this most excellent (but heavy) lens:

http://www.l-camera-forum.com/leica-wiki.en/index.php/180mm_f/3.4_APO-Telyt-R

 jhinkey's gear list:jhinkey's gear list
Panasonic Lumix DMC-TS3 Panasonic Lumix DMC-LX7 Panasonic Lumix DMC-GH2 Nikon D800 Panasonic Lumix DMC-G5 +19 more
Reply   Reply with quote   Complain
gteague
Contributing MemberPosts: 930Gear list
Like?
Re: GX7 Lens Review on DxO
In reply to jhinkey, 7 months ago

you're right, i apologize. got focal length dyslexia for some reason. too many equivalency computations you have to run through nowadays with all the sensor sizes. in my long ago world of film you had many film sizes but very few lenses with any formats other than 35mm and 2-1/4, so it wasn't that difficult to keep everything straight. [g]

yeah, i've only ever seen that lens in books and catalogs although i once tried to use the leitz system. i found out that their very vaunted rangefinders weren't and thus the illusion was shattered. i saved up for years to finally buy into that system and it crushed me to find out their reputation was all marketing and myth--or at least it was by the time i got there.

/guy

-- hide signature --

"The world is going to pieces and people like Adams and Weston are photographing rocks!" ~Henri Cartier-Bresson

 gteague's gear list:gteague's gear list
Sony RX100 RX100 III Panasonic Lumix DMC-GX1 Panasonic Lumix DMC-GX7 Olympus M.Zuiko Digital ED 9-18mm 1:4.0-5.6 +4 more
Reply   Reply with quote   Complain
Keyboard shortcuts:
FForum MMy threads