THE SIGMA DP MERRILL COLOURS: THE TRUTH REVEALED!
PUTTING AN ARGUMENT TO REST: THE TRUTH ABOUT THE SIGMA DP MERRILL COLOURS
Since the recent release of the Sigma DP3 Merrill, the Internet has been full of arguments about the Sigma DP Merrill colours. In particular, people started wondering whether the DP3M handled colour differently, and more specifically better, than its older siblings, the Sigma DP1 Merrill and Sigma DP2 Merrill.
Some said the Sigma DP3 Merrill colours (DP3M from now on) were much better than the Sigma DP1 Merrill colours and Sigma DP2 Merrill colours (DP1M and DP2M from now on). Others said there weren’t any differences. However, nobody provided any hard evidence to substantiate either claim.
For sure, Sigma didn’t announce any changes in camera hardware or any differences in firmware that could justify any difference in image quality and colours. However, we all know that manufacturers often do change minor things in a product lifetime, for the most different reasons, without informing the public.
When I finally got the DP3M in my hands, I was very curious to see with my own eyes where things stood. So, before taking the camera out for a spin in the real world, I decided to try and put this issue to rest doing a quick, controlled in-house test. I wanted to leave behind, once and for all, these more or less substantiated rumours and all the internet noise going with them.
So what’s the verdict? Are there any differences in output and colour handling between the three Sigma DP Merrill colours? Read on to find out!
Disclaimer: At the time of writing, I am not affiliated with Sigma in any way. I am a professional photographer looking for the best equipment for my work, I buy all my gear with my hard-earned cash and I don’t get paid by anyone to write articles for my blog.
Keeping in mind that my purpose here was to compare the three DP Merrill colours, the only important thing was examining all three cameras under the exact same conditions, rather than what these conditions were.
Comparing different cameras’ colour response can be tricky, due to the many variables involved. In order to remove as many of these variables as possible, I shot 3 series of pictures of my unexciting subject, a X-Rite colour chart, under consistent flash light and using three different WB settings.
In particular, I used Auto WB in the first set to see what each camera’s own idea of colours were.
In the second set, I used Flash WB to see how each camera’s preset worked. Finally, for the last set I did a spot WB in Sigma Photo Pro 5.5.1 to check each camera’s colour response when using a perfectly correct WB.
All cameras have been set to manual mode, and an exposure of 1/125 second at f8, ISO 100, has been used for all photographs with all cameras. Finally:
– All cameras have been updated to the latest firmware available;
– Cameras were placed on a tripod;
– Flash was fixed on a stand slightly up and camera right, and its position didn’t change between shots;
– To prevent different amounts of white wall from influencing WB and colour response and to keep the chart’s magnification the same in each image series, camera positions were adjusted to compensate for different focal lengths;
– Images have been shot as RAW in AdobeRGB colour space;
– Images have been processed in Sigma Photo Pro 5.5.1 applying the exact same settings for each file: contrast +1, exposure +0.5, colour set to neutral, all other setting to zero;
– Images have then been exported as 16bit TIFF;
– TIFFs have been opened in Photoshop CS6;
– A 10, 1.2, 250 level correction has been applied to each image;
– Colours have been spot-measured using a 31px checker to have a large enough sampling area;
– For your convenience, resulting RGB values have been written over each checker;
– Images have been saved as 8bit sRGB JPGs.
For brevity, I’ll leave the interpretation of individual RGB value sets to you, limiting my analysis of the results to the differences in exposure and colour rendering.
AUTO WHITE BALANCE
First, let’s have a look at the Auto WB series, to see how differently the three cameras “see” colours when left all by themselves under a pretty standard, consistent and “easy” light such as flash light (click on the images to enlarge):
Exposure. It is interesting to see how the three DP Merrill cameras show such different sensitivity to light, despite sporting the exact same sensor. In increasing order of sensitivity, first comes the DP1M, then the DP2M and finally the DP3M, the most sensitive of all. Different lens designs with consequent different angles of incidence of light on the sensors are very likely responsible for these differences in exposure. Generally speaking, the longer and / or the more tele-centric the lenses are, the more efficient they are at collecting light. We see that pattern here when progressing from 19mm to 30mm and finally to 50mm lenses illuminating the same sensor.
Colour Rendering. First of all, note how all three cameras “get the blues” when left in Auto WB. All images show a pronounced cyan cast. Leaving that aside, and taking into account some small variations in exposure, the RGB values’ output of the Sigma DP1M and DP2M is pretty much identical. On the other hand, the DP3M renders colours very differently in Auto WB, even accounting for the differences in exposure. Check out the red / pink checkers, the brown, the cyan (above the black one) and the yellow / orange ones, and you will see that the balance between R, G & B is very different. In short, I’d say more R, G and less B in the red / pink and yellow / orange tones; more G in the cyan above the black; more R in the brown top left. All other colours, greys included, are pretty much the same between the three cameras.
FLASH WHITE BALANCE
Let’s now move to the Flash WB set (click on the images to enlarge):
Exposure. You can easily spot the differences in exposure between the three cameras in this series as well, with the DP3M again being the most generous of all Merrill.
Colour Rendering. While all three cameras still get the blues under Flash WB, the DP3M definitely behaves much better than the DP1M and DP2M. Check the grey checkers in the DP3M’s image’s last row to see how R, G & B are more balanced and actually pretty close to being neutral, except for a slightly weak red channel. Compared to Auto WB, under Flash WB the DP3M displays more R and less B. This time, it does so all over the spectrum, not just for certain colours as in the previous sample set and its rendering is overall more balanced and closer to reality.
CUSTOM WHITE BALANCE
Let’s now see what happens doing a Custom WB reading, using the third grey spot from the left for all images (click on the images to enlarge):
Exposure. The usual pattern is repeated here, with the DP3M creating brighter images than its siblings at equivalent exposure.
Colour Rendering. First of all, as you can see spot WB works very well and the greys in all images are all pretty neutral (as expected). That said, taking exposure differences into account, we can spot some very minor differences not only between the DP1M and DP2M versus the DP3M, but between the DP1M and DP2M as well. Look at the red, yellow and orange squares in the DP1M vs. DP2M images and you’ll notice that the DP2M outputs less B in these colours than the DP1M. Look then at the same squares in the DP3M vs. DP2M, and you’ll notice that the DP3M outputs less G than the DP2M, producing “redder” reds and pinks than the DP2M.
Let’s now try and bring this little experiment to a conclusion.
Using Auto WB, or a preset WB such as Flash WB, the DP1M and DP2M show a very similar behaviour. The DP3M, on the other hand, behaves in a quite different way. While I only tested one preset in controlled conditions, Flash WB, casual use of the Merrills leads me to believe this to be a general behaviour of these three cameras using all presets.
Using Spot WB in Sigma Photo Pro, the DP2M and the DP3M behave very closely to each other, showing only some minor differences in the reds and pinks. The DP3M, on the other hand, outputs less G in these wavelengths, therefore making reds and pinks look “redder” to me. All other colours look pretty much exactly the same. The DP1M, on the other hand, offers a slightly different colour rendition, showing a little more B in the red, yellow and orange checkers.
This test was designed to show the differences between the three DP Merrill cameras colours, rather than as a test of their absolute colour accuracy. However, while I was at it, I quickly confronted the values resulting from my tests above with those provided by X-Rite as a reference Colorimetric Values for their family of targets. The most striking result is how Sigma’s Auto WB is way off even under such a pretty standard light as flash, with all three cameras. Using Sigma’s Flash WB preset, results are closer to the chart reference values, but they are off nevertheless. Less so with the DP3M, more dramatically so with the DP1M and DP2M. Custom WB is of course the closest of all. While it would be interesting to perform a controlled test to see what the DP1M, DP2M and DP3M colour behaviour is in absolute terms, this is beyond the scope of this article.
As well, even if not colour-related, I’d like to point out once more the metering differences between these cameras. The DP1M exposes most conservatively, the DP2M sits in the middle and the DP3M is the most generous of all. This won’t bother people owning one Merrill camera only, or people using only one camera at a time. It might not bother much people using an automated exposure mode either. However, it can become very frustrating for people shooting in manual mode with more than one camera at a time, as I do. If you use more than one DP Merrill camera at a time, you’ll need to remember this and compensate accordingly, because just porting one camera’s exposure to the next would result in either underexposure or overexposure, but never in consistent exposures between cameras.
To sum things up, it is clear to me that there are indeed some differences in the Sigma DP Merrill colours. In particular, it seems to me that Sigma changed the colour output of the DP3M noticeably when ANY in camera WB presets are being used. Using Custom WB in Sigma Photo Pro 5.5.1, on the other hand, the three DP Merrill cameras colours are much closer to one other. So much so that most users wouldn’t notice any differences at all, and that whatever differences there are can be fixed easily enough in post-processing.
Personally, I find the DP3M output when using Auto WB or WB presets the most accurate of all DP Merrill cameras, and I surely hope Sigma will bring these changes to the DP1M and DP2M as well via FW updates. Using Custom WB, as any serious photographer would do for critical work anyway, all three cameras produce perfectly usable colours. I hope this test will finally put all arguments about the differences between the three Sigma DP Merrill colours to rest.
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