DP2m: first images, first problems

mclaudio wrote:

(•) First images

WOW - it seems you have used at least one other camera before I am impressed. Nice images.

(•) First (usual) problems
(1) My main concern regards the purple/green areas in the clouds that I obtain in highly contrasted skies. Following the recommendation found in this forum I tried (in LR5): desaturating the purple/magenta channels; moving the hue of the purple channel towards the blue; using color noise reduction; using local moire/fringe correction. Nothing really works for me, there are some improvements in some cases but the purple/green areas often do not completely disappear, you can find some of them also in the images I posted. Maybe this is linked to the (incorrect) exposure of the photo, even though, honestly, I’m not sure of that. But the exposure is a sort of nightmare with this DP2m. In highly contrasted situations the meter is off up to 2 stops, the live view histogram and the screen preview are totally useless (in some cases the histogram does not change even correcting the exposure of 4 stops, it does not move at all, the same for the preview (my firmware is v1.05, the DP2 is imprecise but it is relatively consistent)) and highlights are quite easy to clip.

The purple/green is somewhat mysterious. Sometimes there is none, and then, all of a sudden you have lots of it. I know why it is there, but I have a hard time predicting when it is a risk for it.

(2) My second concern is about micro contrast. In some case it is really too high for my taste, I like better the one of the original DP2. To reduce it I decrease the contrast and the presence (in LR5), but still I’m not completely happy with the results.

For some mysterious reason, Sigma has chosen to (by default) enhance local contrast greatly for Merrill sensors. In later versions of SPP you are supposed to be able to "fix" that by using portrait mode. OK - that gritty, dirty look when the local contrast is exaggerated has its charm, but gets tiresome in the long run IMHO. BTW, it is not really micro contrast, which is at pixel level, but rather like using "clarity" in Lightroom, adding higher contrast to textures.

(3) The WB and the colors are improved w.r.t. the ones of the DP2. I use AWB that I correct to my taste in SPP, but some times it is quite difficult to find a good WB. I know that somebody hate AWB, but when I try all the other WB options in SPP they are really far from the one I like (in general they have a strong yellowish cast). I never understood if there is a difference to change the WB in SPP or to use directly a specific WB when one takes the image.

Colorwise, the Foveon sensors are strange beasts. White balance is not, like for RGB cameras, a matter of balance between the RGB channels. There are different conversion matrices for each white balance. Many have been the problems seen when trying to fix colors. Now, the later cameras (e.g. Merrill and Quattro) are better than ever regarding color.

So, if you have a strange lighting, you'd better measure it using AWB or using custom WB. Can be a bit tricky otherwise.