I’ve tinkered with Sigma sd Quattro’s DNG support for quite some time now. On paper it’s great to have the option to develop Sigma RAWs in other programs. But what can you expect if you shoot DNGs with your sd Quattro and subsequently develop them in Lightroom? Is it silly to expect an equivalent output to Sigma Photo Pro?
Before we dig into it let me bring your attention to the following points:
- I set the sd Quattro to M mode and set all settings manually, in order to make the photos as comparable as possible.
- I used a flash gun for the same reason as under point 1. I’m a passionate ambient light shooter, but there is no denying that flash is more reliable and thus is the way to go regarding comparisons such as this one.
- It’s almost impossible to develop RAWs in Lightroom and SPP in a way, that they end up identical. I’ve tried hard to equalize WB, exposure, contrast, shadows, highlights and saturation.
- Ignore sharpness and luminance noise. These two parameters are dependent on each other and are easy to equalize across software, if needed. In order to keep the workload down, I ended up using standard presets in SPP and LR: 0 in the former and 25 in the latter.
- Chrominance noise reduction was disabled in order to better compare “color lumps”. Unlike sharpness and luminance noise “color lumps” (or “color clouds”) are not as easy to get rid of. They are pretty much PITA!
- Unless otherwise mentioned, in all the comparison images SPP is always on the right.
Micro contrast and color lumps
Let’s take a look at micro contrast and color lumps by means of the following photo.
As you can see in the following crop, there is a distinct difference between Sigma Photo Pro and Lightroom regarding micro contrast. The texture of the peeled carrots in the photo, which was developed in LR (right), is not as apparent as in the other one, which was developed in SPP.
The following crop makes it clear just how different the two RAW developers are when it comes to color lumps. SPP tends to produce more visible color lumps in parts with relatively uniform colors and brightness values. On the other side there are no problems along the edges. LR, however, produces diametrically different output: clean uniform areas and apparent color lumps along the edges.
Out of the box Lightroom‘s color rendition is problematic. In the following photo LR renders the color orange too green in comparison to SPP. Color perception, however, is different from person to person, which is why many photographers will prefer the photo, which was developed in LR.
There are similar differences in regard to other colors. But this particular issue is less problematic than the following ones.
Brightness dependent color cast and „color stretch marks”
I deliberately underexposed the following photo by 2 stops, because I wanted to see what happens when you boost exposure in these two RAW developers. As one would expect, the unedited photo looks very dark.
After you boost exposure by 2 EVs and set other settings in a way, which will make the end result as comparable as possible, mayor differences crop out.
Firstly, Lightroom doesn’t seem capable of calculating color independently of brightness values, in areas of uniform color. What I mean by that, is, that unlike SPP the tomato doesn’t look red everywhere. Color in the highlights appears cold. Some parts look red (mid tones), while others are a mix of red and orange / green. Secondly, there is an extremely intensive magenta color cast in the shadows. And thirdly, take a look at the bottom left corner. The image artifact, which can only be described as „color stretch marks”, is impossible to miss. It’s also present in the photo, which was developed in SPP, but you really have to look for it.
But let’s return to the first point, the brightness dependent color cast. To be sure that it’s not a result of severe under exposure and consequent exposure boosting, I took additional two photos with normal exposure.
Color casts are definitely there, even if the photos are unproblematic due to being exposed properly. In the photo above you can clearly see that kiwis, which are in the shadow, have a cold color cast, while the ones, which had gotten a lot of light, have a green one.
Before I began comparing Sigma Photo Pro with Lightroom, I was willing to bet, that highlight recovery is the area where I would find the largest difference. Contrary to my expectations SPP and LR are comparably good when it comes to HR. I’ve overexposed a DNG and a X3F by about 1.67 EVs, so that you can form your own opinion.
Afterwards I adjusted exposure and other settings to obtain comparable results.
This is what the images look like side by side (SPP left; LR right):
The area with missing detail is identical in size in both photos.
We Sigma users are always on the look-out for faster SPP alternatives. The DNG support gave us hope, that in the future we could develop our RAWs in Lightroom and other RAW developers that support the DNG format. LR and similar developers have the advantage of faster processing and of being an indispensable component of your workflow, in case you are also shooting with cameras with bayer sensors. Unfortunately Lightroom fails completely. DNGs developed in LR have lower micro contrast and an abundance of different image artifacts, from color lumps to “color stretch marks”.
Sigma Photo Pro therefore remains by far the best, albeit slowest, RAW developing software for Sigma cameras.
You can view all the images in full resolution on flickr.