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Sigma DP2 Pentax K-x comparison [image heavy]
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PostPosted: Mon Dec 20, 2010 4:40 pm    Post subject: Sigma DP2 Pentax K-x comparison [image heavy] Reply with quote

Since nobody took up the challenge I posted in my DP1 thread, I quickly processed the DP2 and Kx RAW files I shot last Saturday for a brief comparison. The files are here if you want to experiment and post your processed versions.

I wanted to test a scenario which will be familiar to many:

* each camera files were developed with their default RAW converters, Silkypix for the Pentax (the Pentax utility is a dumbed down version of Silkypx), and Sigma Photo Pro for the Sigma

* I did minimal processing and did not resort to complex settings or wb fine tuning, as most of the times RAW files get special treatment only in case of evident problems, and in my opinion the fact that a camera/raw processor combination gives good results out of the box in most situations without having to resort to wizardry is important

* I set the cameras to their lowest ISO setting (200 for the Pentax, 50 for the DP2) and used their auto WB; when developing, I let the RAW developer adjust wb and exposure, which in this situation worked ok with no great deviation from the values choosen by the cameras (apart from correcting the slight underexposure typical to most Pentax cameras)

* the Pentax is at a slight disadvantage, as it uses a decent zoom (Tokina RMC 25-50mm f/4) while the Sigma has a stellar fixed focal lens; furthermore, I scaled down the Pentax files to match the Sigma image size (but Silkypix applied a light USM so that evens out things a bit)

Ok, here are the images, first one is always the Pentax version.

















My first impressions are that the Sigma, despite the lower Mp count, is capable of resolving a huge amount of detail; its lens is also very good, and its color accuracy and microcontrast much better than the Pentax. Colors on the Pentax are duller in the shade, and cartoonish in good light, which is something I have observed at other times too. And in favourable conditions, the DP2 has a film-like quality, with something of a 3D effect.

Even despite the obvious limitations of this test, it's pretty obvious that considering the DPx cameras as point-and-shoots is a huge mistake. Not only their sensor is as large as many DSLRs, their lenses are very good and image quality can be exceptional.


Last edited by ludoo on Thu Jan 13, 2011 6:52 am; edited 1 time in total


PostPosted: Tue Dec 21, 2010 8:51 pm    Post subject: Reply with quote

I think you should develop both the pictures of the Pentax and the Sigma in the same RAW software, f.i. in Lightroom. Probably the default settings of both programs are not similar.


PostPosted: Tue Dec 21, 2010 8:53 pm    Post subject: Reply with quote

I think the right way is to develop each camera files with its own optimized developer. Smile

I'm not checking how a raw developer works with different formats, but how each camera renders the same scene under normal conditions, those used in real life when shooting with each camera.

Anyway, the files are downloadable so if some Lightroom user wants to have a go at it, he is welcome. Smile


PostPosted: Tue Dec 21, 2010 10:18 pm    Post subject: Reply with quote

I get similar results if I develop both RAW files in lightroom. You've already mentioned the limitations of your test. I agree with that: fit the Pentax with a good prime, and the results will definitely look (much) better.

But I think you have made your point: point and shoots don't compare to a camera like the DP2 with its superior big sensor. And I also agree megapixels and details are two different things.


PostPosted: Tue Dec 21, 2010 10:37 pm    Post subject: Reply with quote

caspert79 wrote:
But I think you have made your point: point and shoots don't compare to a camera like the DP2 with its superior big sensor. And I also agree megapixels and details are two different things.


Exactly. And in good light the Foveon sensor has its advantages. Of course, after 800 ISO or even 400, the Pentax (or any modern DSLR) has a definite advantage.

A good prime will make the Pentax images a bit sharper, but I still think the Foveon would have better details and microcontrast. Which makes me very curious about the upcoming Sigma SD1, the first shots on Carl Rytterfalk's blog are amazing.


PostPosted: Tue Dec 21, 2010 11:50 pm    Post subject: Reply with quote

ludoo wrote:
I think the right way is to develop each camera files with its own optimized developer. Smile
I'm not checking how a raw developer works with different formats, but how each camera renders the same scene under normal conditions, those used in real life when shooting with each camera.


But Ludo, you are always "testing" raw developers, unless you shoot jpg.
So I think for a comparison to have a common ground, either you test jpgs, or you test the raw files on an identical platform, that is "third party" for both, so nobody gets an advantage.


PostPosted: Wed Dec 22, 2010 6:37 am    Post subject: Reply with quote

Orio wrote:
ludoo wrote:
I think the right way is to develop each camera files with its own optimized developer. Smile
I'm not checking how a raw developer works with different formats, but how each camera renders the same scene under normal conditions, those used in real life when shooting with each camera.


But Ludo, you are always "testing" raw developers, unless you shoot jpg.
So I think for a comparison to have a common ground, either you test jpgs, or you test the raw files on an identical platform, that is "third party" for both, so nobody gets an advantage.


Unfortunately, I don't think what you're describing is possible in this case... However you do it, one camera would always be disadvantaged from the start. Neutral


Here is why:

First, the JPG comparisons. It is well known that the Sigma/Foveon cameras have historically favored a raw workflow, to the effect that Sigma has prioritized development of SPP, and put less attention toward optimizing the in-camera JPG results. To most, this is an acceptable tradeoff - and simplifying the in-camera processing also benefits camera performance and battery life.

However, with this admission on the table, would it be "fair" to compare the handicapped Sigma JPGs to those from other cameras? Question



Second, the "common" or "identical" raw converters. The problem with this case is that the Foveon raw image processing pipeline is fundamentally different than the Bayer raw image pipeline. The de-matrixing, the interpolation, the color balancing, the noise reduction, the baseline sharpening... it's all different. As a result, a Bayer RAW and a Foveon X3F are going to have completely different processing paths, even if processed within the same software package. There really is no way around this.

Once we have understood this, then we can see that even with the single "common" raw developer, it really still does come down to a comparison of two separate raw converters once again - just in this case, the two happen to live within the same software package. Wink

Where the imbalance comes to play is that "common developer" providers such as Adobe have years more experience developing & tuning Bayer algorithms, and the results of these efforts benefit the large majority of their user base. Support for Foveon-based cameras has always been a second priority, and with the (relatively) low user count, they really don't have the business case to invest too much in developing the Foveon-specific algorithms to the same level as their Bayer algorithms. This is in contrast to Foveon (now Sigma), who stakes their entire survival on how well their raw converter performs. Wink



Because of all of this, I would have to agree with ludoo - comparing the end results, using the best available raw converter for each camera, is probably the most "fair" option available. Wink


PostPosted: Wed Dec 22, 2010 7:52 am    Post subject: Reply with quote

Scheimpflug, thanks for the "scientific" and very clear explanation.

And Orio, with in-camera jpg you are in fact comparing two RAW developers, made by dedicated chips and proprietary firmware instead of an Intel or AMD processor and computer software. What's the point, especially for people who shoot RAW?